Background B chromosomes, also known as supernumerary or accessory chromosomes, are additional chromosomes over the standard complement found in various groups of plants and animals. We investigated the presence of, and characterized, supernumerary microchromosomes in Astyanax goyacensis using classical and molecular cytogenetic methods. Findings Three specimens possessed 2n = 50 chromosomes (8m + 26sm + 8st + 8a), and two specimens contained 1 to 9 additional B microchromosomes varying intra- and inter-individually. Chromosome painting with a B chromosome-specific probe yielded signals for several B microchromosomes, with one exhibiting no markings. Acrocentric chromosomes of the standard complement were also painted. Fluorescence in situ hybridization (FISH) using ribosomal probes located two chromosome pairs carrying 18S rDNA marked on the short arm, and one pair carrying 5S rDNA with pericentromeric markings. One chromosome was observed in synteny with 18S cistrons. Conclusion These data contribute to knowledge of the karyotype evolution, the origin of B chromosomes, and to an understanding of the functionality of rDNA. PMID:24192310
Zanata, A M; Birindelli, J L O; Moreira, C R
A new species of Moenkhausia is described from Rio Xingu and Rio Tapajós basins, Brazil. The new species is distinguished from its congeners, except from Moenkhausia moisae, by having more scales in the lateral series, 43-47 (v. 23-41 in the remaining congeners). The new species is distinguished from M. moisae by its colour pattern, which consists of a dark midlateral stripe, and an asymmetrical caudal blotch (inconspicuous or faded in specimens from the Rio Arinos) continuous with the midlateral stripe (v. narrow dark midlateral line and conspicuous, regularly rounded and symmetrical blotch not continuous with the midlateral line). The new species is putatively assumed to be mimetic to Jupiaba apenima, in the Rio Xingu and Rio Teles Pires drainages, and to Jupiaba yarina in the Rio Arinos. The two species of Jupiaba are sympatric and remarkably similar in size, general external morphology and colouration to the new species. A small difference occurs in the colouration between the two species of Jupiaba and is also observed in the two respectively sympatric morphotypes of the new species of Moenkhausia. The occurrence of polymorphic Batesian mimicry is therefore discussed for neotropical freshwater fishes.
Park, Jae-Min; Han, Kyeong-Ho; Han, Ran
We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium (50×50×30 cm). Breeding water temperature was 27.5~28.5°C (mean 28.0±0.05°C) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean 0.74±0.07 mm, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean 3.84±0.04 mm, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean 10.9±1.66 mm), and it had similar silver-colored body shape with its mother.
Reys, Paula; Sabino, José; Galetti, Mauro
Frugivory and seed dispersal have been poorly studied in Neotropical freshwater fishes. We studied frugivory and seed dispersal by the piraputanga fish ( Brycon hilarii, Characidae) in the Formoso River, Bonito, western Brazil. We examined the stomach contents of 87 fish and found the diet of piraputanga consisted of 24% animal prey (arthropods, snails, and vertebrates), 31% seeds/fruits and 45% other plant material (algae/macrophytes/leaves/flowers). The piraputangas fed on 12 fruit species, and were considered as seed dispersers of eight species. Fruits with soft seeds larger than 10 mm were triturated, but all species with small seeds (e.g. Ficus, Psidium) and one species with large hard seed ( Chrysophyllum gonocarpum) were dispersed. Piraputangas eat more fruits in the dry season just before the migration, but not during the spawning season. Fish length had a positive relation with the presence of fruits in their guts. The gallery forest of the Formoso River apparently does not have any plant species that depend exclusively on B. hilarii for seed dispersal because all fruit species are also dispersed by birds and mammals. Based on seed size and husk hardness of the riparian plant community of Formoso River, however, the piraputangas may potentially disperse at least 50% of the riparian fleshy fruit species and may be particularly important for long-distance dispersal. Therefore, overfishing or other anthropogenic disturbances to the populations of piraputanga may have negative consequences for the riparian forests in this region.
Background With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity. Results In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses. Conclusion A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance
Marinho, M M F; Langeani, F
A new species of Characidae, Moenkhausia celibela, is described from the Rio Amazonas at Santarém, Rio Maraú, several localities in the Rio Tapajós, Rio Curuá-Una, Rio Xingu and Rio Jari, all from the Amazon basin, Brazil. The new species is distinguished from its congeners, except species included in Géry's 1992 Moenkhausia lepidura group, by presenting a dark blotch on the upper caudal-fin lobe, and the lower lobe is hyaline or light grey. Moenkhausia celibela is distinguished from the species of the M. lepidura group by the absence of a humeral spot and the presence of a roughly triangular and dark spot at the caudal-fin base, extending posteriorly along the middle caudal-fin rays, and distinctly separate from the spot on the upper caudal-fin lobe.
Scudeler, Patricia Elda Sobrinho; Diniz, Débora; Wasko, Adriane Pinto; Oliveira, Claudio; Foresti, Fausto
B chromosomes are dispensable genomic elements found in different groups of animals and plants. In the present study, a whole chromosome probe was generated from a specific heterochromatic B chromosome occurring in cells of the characidae fish Moenkhausia sanctaefilomenae (Steindachner, 1907). The chromosome painting probes were used in fluorescence in situ hybridization (FISH) experiments for the assessment of metaphase chromosomes obtained from individuals from three populations of Moenkhausia sanctaefilomenae. The results revealed that DNA sequences were shared between a specific B chromosome and many chromosomes of the A complement in all populations analyzed, suggesting a possible intra-specific origin of these B chromosomes. However, no hybridization signals were observed in other B chromosomes found in the same individuals, implying a possible independent origin of B chromosome variants in this species. FISH experiments using 18S rDNA probes revealed the presence of non-active ribosomal genes in some B chromosomes and in some chromosomes of the A complement, suggesting that at least two types of B chromosomes had an independent origin. The role of heterochromatic segments and ribosomal sequences in the origin of B chromosomes were discussed.
Scudeler, Patricia Elda Sobrinho; Diniz, Débora; Wasko, Adriane Pinto; Oliveira, Claudio; Foresti, Fausto
Abstract B chromosomes are dispensable genomic elements found in different groups of animals and plants. In the present study, a whole chromosome probe was generated from a specific heterochromatic B chromosome occurring in cells of the characidae fish Moenkhausia sanctaefilomenae (Steindachner, 1907). The chromosome painting probes were used in fluorescence in situ hybridization (FISH) experiments for the assessment of metaphase chromosomes obtained from individuals from three populations of Moenkhausia sanctaefilomenae. The results revealed that DNA sequences were shared between a specific B chromosome and many chromosomes of the A complement in all populations analyzed, suggesting a possible intra-specific origin of these B chromosomes. However, no hybridization signals were observed in other B chromosomes found in the same individuals, implying a possible independent origin of B chromosome variants in this species. FISH experiments using 18S rDNA probes revealed the presence of non-active ribosomal genes in some B chromosomes and in some chromosomes of the A complement, suggesting that at least two types of B chromosomes had an independent origin. The role of heterochromatic segments and ribosomal sequences in the origin of B chromosomes were discussed. PMID:26753081
Melo, Bruno F; Benine, Ricardo C; Silva, Gabriel S C; Avelino, Gleisy S; Oliveira, Claudio
Tetragonopterinae encompasses characid species of the genus Tetragonopterus, which are widely distributed throughout east of the Andes in South America. While taxonomy has recently clarified the species diversity and molecular evidence strongly supports the monophyly of Tetragonopterus, no interspecific relationship studies are currently available. Here we used a large molecular dataset composed of two mitochondrial and three nuclear loci containing an extensive taxon sampling within the family Characidae and included eleven species of Tetragonopterus to generate the first time-calibrated phylogeny for Tetragonopterinae. Our results support monophyly of the subfamily represented solely by Tetragonopterus and corroborate previous molecular hypothesis of close relationship with Exodon plus Roeboexodon and the subfamily Characinae. Internally, we found Moenkhausia georgiae as sister species to all remaining species followed by T. rarus, being both species endemic to the Guiana Shield drainages. Species-level relationships are first hypothesized and putative morphological apomorphies are discussed as support to monophyletic clades. Our time-calibrated phylogeny suggested an origin of the genus during the Late Oligocene-Early Miocene. We hypothesized that the Andean geological activity followed by transformations in the Amazonian hydrographic scenario during the Miocene may have promoted most of the lineage diversification within the Tetragonopterus.
Small, Gaston E; Pringle, Catherine M; Pyron, Mark; Duff, John H
Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors controlling the relative contribution of 12 Neotropical fish species to nutrient recycling in four streams spanning a range of phosphorus (P) levels. In high-P conditions (135 microg/L soluble reactive phosphorus, SRP), most species fed on P-enriched diets and P excretion rates were high across species. In low-P conditions (3 microg/L SRP), aquatic food resources were depleted in P, and species with higher body P content showed low rates of P recycling. However, fishes that were subsidized by terrestrial inputs were decoupled from aquatic P availability and therefore excreted P at disproportionately high rates. One of these species, Astyanax aeneus (Characidae), represented 12% of the total population and 18% of the total biomass of the fish assemblage in our focal low-P study stream but had P excretion rates > 10-fold higher than other abundant fishes. As a result, we estimated that P excretion by A. aeneus accounted for 90% of the P recycled by this fish assemblage and also supplied approximately 90% of the stream P demand in this P-limited ecosystem. Nitrogen excretion rates showed little variation among species, and the contribution of a given species to ecosystem N recycling was largely dependent upon the total biomass of that species. Because of the high variability in P excretion rates among fish species, ecosystem-level P recycling could be particularly sensitive to changes in fish community structure in P-limited systems.
Small, G.E.; Pringle, C.M.; Pyron, M.; Duff, J.H.
Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors controlling the relative contribution of 12 Neotropical fish species to nutrient recycling in four streams spanning a range of phosphorus (P) levels. In high-P conditions (135 ??g/L soluble reactive phosphorus, SRP), most species fed on P-enriched diets and P excretion rates were high across species. In low-P conditions (3 ??g/L SRP), aquatic food resources were depleted in P, and species with higher body P content showed low rates of P recycling. However, fishes that were subsidized by terrestrial inputs were decoupled from aquatic P availability and therefore excreted P at disproportionately high rates. One of these species, Astyanax aeneus (Characidae), represented 12% of the total population and 18% of the total biomass of the fish assemblage in our focal low-P study stream but had P excretion rates >10-fold higher than other abundant fishes. As a result, we estimated that P excretion by A. aeneus accounted for 90% of the P recycled by this fish assemblage and also supplied ???90% of the stream P demand in this P-limited ecosystem. Nitrogen excretion rates showed little variation among species, and the contribution of a given species to ecosystem N recycling was largely dependent upon the total biomass of that species. Because of the high variability in P excretion rates among fish species, ecosystem-level P recycling could be particularly sensitive to changes in fish community structure in P-limited systems. ?? 2011 by the Ecological Society of America.
Piscor, Diovani; Parise-Maltempi, Patricia Pasquali
Abstract The Hyphessobrycon are allocated in the incertae sedis group of the Characidae family, one of the genera with more species of the group. The chromosomes of some species of Hyphessobrycon are known, and the diploid number most common for genus is 2n = 50 chromosomes. The aims of this study were to examine the karyotype macrostructure in the Hyphessobrycon eques Steindachner, 1882, and show a new origin hypothesis for B chromosomes. The diploid number observed for Hyphessobrycon eques was 2n = 52 chromosomes, and a karyotype formulae of 12m + 18sm + 8st + 14a, with FN (fundamental number) = 90 for both sexes. Only two females showed one B chromosome. The heterochromatin was observed mainly on centromeric regions, and in the long arm of the B chromosome. In this paper, the relationship of the B chromosome of Hyphessobrycon eques with an occasional chromosome rearrangement was discussed. PMID:26310656
Garavello, J C; Sampaio, F A A
Five new species of the Neotropical characiform genus Astyanax Baird & Girard are described from Rio Iguaçu at the border of Paraná and Santa Catarina states, southeastern Brazil and Astyanax gymnogenis Eigenmann is redescribed. Each new species can be distinguished from all other Astyanax species from the upper Rio Paraná basin by exclusive combinations of: tooth shape, number of dental cuspids, distance between third infraorbital and preopercle, number of lateral line scales, longitudinal series of scales, number of gill-rakers and differences from shape of body and head traits. This study proposes the species of genus Astyanax from Rio Iguaçu as probably endemic, since all of them are absent from tributaries of the Rio Paraná hydrographic system. The high degree of diversification acquired by those Astyanax species in the Iguaçu basin may perhaps be allied to the long isolation period of this river from the Rio Paraná basin caused by the Iguaçu waterfalls. This barrier probably isolated those basins resulting in original groups of Characiformes and then Astyanax species, both isolated from one another and both different from their relatives in neighbouring basins.
Cytogenetic analysis in the incertae sedis species Astyanax altiparanae Garutti and Britzki, 2000 and Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae) from the upper Paraná river basin
Martinez, Emanuel R. M.; Alves, Anderson L.; Silveira, Sara M.; Foresti, Fausto; Oliveira, Claudio
Abstract Cytogenetic analyses were accomplished in two populations of Astyanax altiparanae Garutti & Britzki, 2000 and one population of Hyphessobrycon eques Steindachner, 1882, considered incertae sedis in Characidae family. Two populations of Astyanax altiparanae (Mogi-Guaçu and Tietê rivers) presented 2n=50, with the same karyotype formula: 6M+12SM+20ST+12A (FN=88). Hyphessobrycon eques from Capivara river presented 2n=52 and karyotype formula 14M+16SM+4ST+18A (FN=86). In each karyotype, the nucleolus organizer regions were detected at the end of the short arm of a single medium-sized subtelocentric chromosome. The Chromomycin A3 (CMA3) marking is coincident for the NORs in chromosomes of the two species and present additionally in two different chromosomes of Astyanax altiparanae thus showinginterpopulation differences in this species. In Hyphessobrycon eques, weak heterochromatic blocks in the position of centromeres and telomeres of most chromosomes and negative C-banding for the NOR bearing chromosome were visualized. The obtained results contribute both to the understanding of karyotype evolution of these species and to the clarifying their phylogenetic relationships. PMID:24260651
Sánchez-Romero, Omar; Abad, César Quezada; Cordero, Patricio Quizhpe; de Sene, Viviani França; Nirchio, Mauro; Oliveira, Claudio
Abstract Karyotypic features of Rhoadsia altipinna Fowler, 1911 from Ecuador were investigated by examining metaphase chromosomes through Giemsa staining, C-banding, Ag-NOR, and two-color-fluorescence in situ hybridization (FISH) for mapping of 18S and 5S ribosomal genes. The species exhibit a karyotype with 2n = 50, composed of 10 metacentric, 26 submetacentric and 14 subtelocentric elements, with a fundamental number FN=86 and is characterized by the presence of a larger metacentric pair (number 1), which is about 2/3 longer than the average length of the rest of the metacentric series. Sex chromosomes were not observed. Heterochromatin is identifiable on 44 chromosomes, distributed in paracentromeric position near the centromere. The first metacentric pair presents two well-defined heterochromatic blocks in paracentromeric position, near the centromere. Impregnation with silver nitrate showed a single pair of Ag-positive NORs localized at terminal regions of the short arms of the subtelocentric chromosome pair number 12. FISH assay confirmed these localization of NORs and revealed that minor rDNA clusters occur interstitially on the larger metacentric pair number 1. Comparison of results here reported with those available on other Characidae permit to hypothesize that the presence of a very large metacentric pair might represent a unique and derived condition that characterize one of four major lineages molecularly identified in this family. PMID:26140168
Highly Similar Morphologies Between Chromosomes Bearing U2 snRNA Gene Clusters in the Group Astyanax Baird and Girard, 1854 (Characiformes, Characidae): An Evolutionary Approach in Species with 2n = 36, 46, 48, and 50.
Piscor, Diovani; Centofante, Liano; Parise-Maltempi, Patricia Pasquali
Repetitive sequences and their chromosomal locations have been widely studied in species of the Astyanax genus. However, the chromosomal organization of U2 snDNA remains largely unknown. The aims of this study were to examine the chromosomal contexts of U2 snRNA and 5S rRNA genes in Astyanax species and determine the degree of chromosome morphological similarity between species with different diploid numbers. Clusters of U2 snDNA and 5S rDNA were determined in nine species of Astyanax, including two karyomorphs of Astyanax fasciatus Cuvier, 1819. All species exhibited U2 snDNA clusters on two chromosome pairs, except Astyanax mexicanus De Filippi, 1853 (one pair). The 5S rDNA clusters were located on one chromosome pair in Astyanax altiparanae Garutti and Britski, 2000, and Astyanax marionae Eigenmann, 1911, two pairs in Astyanax abramis Jenyns, 1842, Astyanax asuncionensis Géry, 1972, Astyanax bockmanni Vari and Castro, 2007, Astyanax eigenmanniorum Cope, 1894, A. fasciatus (karyomorphs I and II), and Astyanax schubarti Britski, 1964, and four pairs in A. mexicanus. The relationships between the repetitive sequences in different species suggest that A. schubarti and A. mexicanus exhibit an unusual U2 snDNA chromosomal format as a result of events occurring in the evolutionary history of the Astyanax group.
During the 1988 rainy season, I studied the 24 h feeding chronology of juvenile (40–68 mm standard length) piranhas, Pygocentrus notatus (Characidae: Serrasalminae) from a natural population inhabiting a small savanna stream in Apure State, Venezuela. Stomach contents analyses, supported by laboratory determinations of digestion rate, showed that these fish are primarily diurnal carnivores. Predatory activity on 4–5 August 1988 increased markedly after sunrise, peaked around 1100 h, and essentially stopped after sunset. Means of stomach content weight-to-fish weight ratios among the periods sampled were significantly different. Small fish were the major prey at all hours (81% of total prey volume). Underlying factors responsible for the observed 24 h feeding patterns were not investigated, but avoidance of predation by adult piranhas, which were very active near sunset, may have been important.
Zanata, Angela M; Lima, Flávio C T; Dario, Fabio DI; Gerhard, Pedro
Astyanax brucutu is described from the rio Pratinha, rio Paraguaçu basin, Bahia, Brazil. The new species is promptly distinguished from other characids by having four, rarely three, robust, rounded, and usualy tricuspid teeth on inner premaxillary series and similar teeth on dentary. The species is furthermore characterized by a series of unusual character states in the Characidae, including head blunt in lateral and dorsal views, longitudinal foreshortening of lower jaw, ventral margin of third infraorbital distinctly separated from horizontal limb of preopercle, leaving a broad area without superficial bones, mesethmoid anteroventrally expanded, and adductor mandibulae and primordial ligament remarkably developed. Analysis of gut contents of adults revealed the almost exclusive presence of crushed shells of tiny gastropods of the family Hydrobiidae. The robust anatomy of jaws, teeth, muscles and associated ligaments are likely adaptations to durophagy, a feeding strategy unusual among characids. Astyanax brucutu is known only from its type locality, an approximately 670 m long, transparent and isolated perennial epigean watercourse surrounded by subterranean or intermittent rivers. The distinctive combination of environmental features characterizing the area of occurrence of the new species is not observed elsewhere in the basin or adjacent basins. A series of severe anthropogenic impacts, associated with the restricted geographic range of the species, implies that A. brucutu should be regarded as Critically Endangered (CR) according to IUCN Red List Criteria.
da Silva, Laura Lahr Lourenço; Giuliano-Caetano, Lucia; Dias, Ana Lúcia
The genus Astyanax comprises 86 species of fish distributed in Brazilian river basins and is considered of the Incertae sedis group within the family Characidae. This study presents an analysis of 12 specimens of Astyanax jacuhiensis from the Tramandai River Basin, RS Brazil: 6 from the Maquiné River and 6 from the Quadros Lagoon. All specimens showed a diploid number equal to 50 chromosomes with different karyotypic formula between the two localities. The population from the Maquiné River showed 10m+26sm+6st+8a (FN=92). Fish from the Quadros Lagoon showed 12m+20sm+6st+12a (FN=88). AgNORs were evidenced in the short arm of one acrocentric chromosome pair in both populations, confirmed by FISH with the 18S rDNA probe. CMA3 fluorochrome corresponded with the AgNOR sites, while DAPI staining was negative in these regions. C banding revealed that heterochromatin was weakly distributed, mainly in the pericentromeric and terminal regions in most chromosomes. Analyses of male gonadal tissue were conducted with the objective of characterizing the meiotic chromosome behavior in A. jacuhiensis. The following stages were evidenced: spermatogonial with 50 chromosomes, pachytene and metaphase I with 25 bivalents, and metaphase II with 25 chromosomes, thus confirming the diploid number of the species. Chromosomal abnormalities were not observed. This study shows preliminary data on A. jacuhiensis from the Tramandai River Basin, contributing with more chromosomal information for this group of fish.
Villela, Luciana Cristine Vasques; Alves, Anderson Luis; Varela, Eduardo Sousa; Yamagishi, Michel Eduardo Beleza; Giachetto, Poliana Fernanda; da Silva, Naiara Milagres Augusto; Ponzetto, Josi Margarete; Paiva, Samuel Rezende; Caetano, Alexandre Rodrigues
The cachara (Pseudoplatystoma reticulatum) is a Neotropical freshwater catfish from family Pimelodidae (Siluriformes) native to Brazil. The species is of relative economic importance for local aquaculture production and basic biological information is under development to help boost efforts to domesticate and raise the species in commercial systems. The complete cachara mitochondrial genome was obtained by assembling Illumina RNA-seq data from pooled samples. The full mitogenome was found to be 16,576 bp in length, showing the same basic structure, order, and genetic organization observed in other Pimelodidae, with 13 protein-coding genes, 2 rNA genes, 22 trNAs, and a control region. Observed base composition was 24.63% T, 28.47% C, 31.45% A, and 15.44% G. With the exception of NAD6 and eight tRNAs, all of the observed mitochondrial genes were found to be coded on the H strand. A total of 107 SNPs were identified in P. reticulatum mtDNA, 67 of which were located in coding regions. Of these SNPs, 10 result in amino acid changes. Analysis of the obtained sequence with 94 publicly available full Siluriformes mitogenomes resulted in a phylogenetic tree that generally agreed with available phylogenetic proposals for the order. The first report of the complete Pseudoplatystoma reticulatum mitochondrial genome sequence revealed general gene organization, structure, content, and order similar to most vertebrates. Specific sequence and content features were observed and may have functional attributes which are now available for further investigation.
Reusing, Ana Flávia; Renesto, Erasmo; Roxo, Fábio F.; Zawadzki, Cláudio H.
Allozyme electrophoresis was used to examine 12 enzymatic systems in two populations of the genus Neoplecostomus from the Paraná River basin. Samples of Neoplecostomus sp. 1 were collected in Paraitinguinha stream of the Tietê River basin, in the municipality of Salesópolis, São Paulo State, and those of Neoplecostomus sp. 2 from São Domingos stream of the Rio Grande River basin, in the municipality of Muzambinho, Minas Gerais State. The genetic variability of the two populations was estimated by Nei’s expected heterozygosity and was considered lower than average for populations of freshwater fish. The proportion of polymorphic loci was low (only 5.26% for the locus Idh). The low frequency of heterozygosity for both populations revealed a high fixation of alleles for each locus. Homozygote excess was observed in both populations. The values of Nei’s genetic identity and the presence of loci with different allele frequencies in both populations may imply that the two populations belong to different species. The genetic variability between populations was compared to other data for loricariids. PMID:21931525
Roxo, Fábio F.; Zawadzki, Cláudio H.; Troy, Waldo P.
Abstract Two new species of Hisonotus are described from the rio Paraná-Paraguay basin in Brazil. The most remarkable features of the new species are the odontodes forming longitudinally aligned rows (one odontode after the other, but not necessarily forming parallel series) on the head and trunk (vs. odontodes not forming longitudinally aligned rows), a pair of rostral plates at the tip of the snout (vs. a single rostral plate), the functional v-shaped spinelet (vs. spinelet non-functional, square-shaped, or absent). These features suggest close phylogenetic relationships with Hisonotus bockmanni, H. insperatus, H. luteofrenatus and H. piracanjuba. Additionally, both new species are distinguished from their congeners by characters related to head length and depth, orbital diameter, suborbital depth, caudal peduncle depth, pectoral-fin spine length, snout length and counts of teeth. Hisonotus paresi sp. n. further differs from its congeners by having contrasting dark geometric spots on the anterodorsal region of the body, a character lacking in H. oliveirai sp. n. The variation in number and shape of the rostral plate, posterior rostrum plates, infraorbitals and the preopercle in both new species and in H. insperatus are discussed. PMID:24715789
Landínez-García, Ricardo M; Alzate, Juan F; Márquez, Edna J
Brycon henni (Characiformes, Bryconidae) is a trans-Andean omnivorous fish considered as promising species in aquaculture of temperate zones. In this work we report for first time the complete mitochondrial genome of B. henni. This mitogenome spans 16,885 bp and encodes 13 proteins, 22 tRNAs and 2 ribosomal RNAs. Additionally, the synteny is conserved with others species of the order Characiformes.
Walsh, Stephen J.; Ribeiro, Frank R.V.; Rapp Py-Daniel, Lúcia H.
The Neotropical catfish genus Tympanopleura, previously synonymized within Ageneiosus, is revalidated and included species are reviewed. Six species are recognized, two of which are described as new. Tympanopleura is distinguished from Ageneiosus by having an enlarged gas bladder not strongly encapsulated in bone; a prominent pseudotympanum consisting of an area on the side of the body devoid of epaxial musculature where the gas bladder contacts the internal coelomic wall; short, blunt head without greatly elongated jaws; and smaller adult body size. Species of Tympanopleura are distinguished from each other on the basis of unique meristic, morphometric, and pigmentation differences. Ageneiosus melanopogon and Tympanopleura nigricollis are junior synonyms ofTympanopleura atronasus. Tympanopleura alta is a junior synonym of Tympanopleura brevis. A lectotype is designated for T. brevis. Ageneiosus madeirensis is a junior synonym of Tympanopleura rondoni. Tympanopleura atronasus, T. brevis, T. longipinna, and T. rondoni are relatively widespread in the middle and upper Amazon River basin. Tympanopleura cryptica is described from relatively few specimens collected in the upper portion of the Amazon River basin in Peru and the middle portion of that basin in Brazil. Tympanopleura piperata is distributed in the upper and middle Amazon River basin, as well as in the Essequibo River drainage of Guyana.
Ballen, Gustavo A; Mojica, José Iván
A new species of Farlowella is described from El Carmen de Chucurí in the Departamento de Santander, western flank of the Cordillera Oriental, río Magdalena Basin, Colombia. Farlowella yarigui n. sp. differs from its congeners in lateral body plate morphology, abdominal cover, cephalic hypertrophied odontodes, and details of coloration. This is the first verifiable record of the genus in the Magdalena drainage. Aspects of natural history and implications of this finding are provided concerning the state of knowledge of the fishes of the río Magdalena Basin. Previous records of Farlowella gracilis in the río Cauca basin are examined and herein considered erroneous, rendering the new species the only representative of the genus in the Magdalena-Cauca system. A key to species of Farlowella from Colombia is provided.
Velasquez-Vottelerd, P.; Anton, Y.; Salazar-Lugo, R.
The freshwater fish Ancistrus brevifilis, which is found in Venezuelan rivers, is considered a potential sentinel fish in ecotoxicological studies. The cadmium (Cd) effect on the mitochondrial viability (MV) and acid soluble thiols levels (AST) in A. brevifilis tissues (liver, kidney, heart, and gill) was evaluated. Forty-two fish with similar sizes and weights were randomly selected, of which 7 fish (with their respective replicate) were exposed for 7 and 30 days to a Cd sublethal concentration (0.1 mg.l-1). We determined the MV through a Janus Green B colorimetric assay and we obtained the concentration of AST by Ellman’s method. Mitochondrial viability decreased in fish exposed to Cd for 30 days with the liver being the most affected tissue. We also detected a significant decrease in AST levels was in fishes exposed to Cd for 7 days in liver and kidney tissues; these results suggests that AST levels are elevated in some tissues may act as cytoprotective and adaptive alternative mechanism related to the ROS detoxification, maintenance redox status and mitochondrial viability. Organ-specifics variations were observed in both assays. We conclude that the Cd exposure effect on AST levels and MV, vary across fish tissues and is related to the exposure duration, the molecule dynamics in different tissues, the organism and environmental conditions. PMID:26623384
Deprá, I C; Gomes, V N; Deprá, G C; Oliveira, I J; Prioli, S M A P; Prioli, A J
Astyanax altiparanae, belonging to the bimaculatus group, which includes species with similar colors and morphology, occurs in the upper Paraná River basin. As the use of mitochondrial DNA has made great strides in the diagnosis of species, in previous researches, two strains were detected in A. altiparanae with a high divergence in the D-loop region, provisionally called AltoPR and AltoPR-D. Evidence led to the hypothesis that the two strains did not belong to the same species. Phylogenetic hypotheses were produced by maximum-likelihood. Mean internal distances of the AltoPR and AltoPR-D groups were respectively 0.002 and 0.003, with the distance between them being 0.037. Sequences from GenBank of specimens collected from the Paraíba do Sul River basin were also divided into two groups, of which one may be identified as AltoPR. Since the other group provided an intermediate distance when compared to AltoPR-D, an in-depth investigation was required. The other species analyzed showed a greater distance and was revealed to be a monophyletic taxon. The results suggested that they are really two species and that neither corresponds to the other species used in the current study.
Mattox, George M T; Britz, Ralf; Toledo-Piza, Mônica
Establishing phylogenetic relationships of miniature fishes is challenging in taxa with developmental truncation. Within the Characiformes, developmental truncation appears to be relatively rare, with the Neotropical genus Priocharax being an example. Priocharax includes three miniature species among the smallest of the order and has been hypothesized to belong to the Heterocharacinae. The pronounced reduction in its skeleton, however, prevented a clearer evaluation of its relationships. The present detailed osteological study was designed to address this question and revealed that 21 bones are absent and nine other skeletal structures are simplified in Priocharax when compared to other characids. Comparison of the skeleton of adult Priocharax with early developmental stages of other characids demonstrated that most of the absences and simplifications can be interpreted as developmental truncations. The most striking developmental truncations are in the pectoral girdle, in which the endoskeleton remains entirely cartilaginous. Other interesting truncations are in the ethmoid region of the skull, infraorbital series, and Weberian apparatus, in which the claustrum is absent. Our study also revealed some unusual sexual dimorphisms in the pelvic girdle. Two cladistic analyses were performed to assess the relationships of Priocharax within the Heterocharacinae. The first consisted of a traditional analysis in which all absences and reductions of Priocharax were coded in the same way as in the remaining taxa. This resulted in three equally most parsimonious topologies, all of which have Priocharax as the most basal taxon of the Heterocharacinae. The second analysis incorporated ontogenetic information, and most absences and reductions of Priocharax were reinterpreted as apomorphic conditions and thus, coded differently from similar conditions in outgroups. This resulted in a single phylogenetic hypothesis with Priocharax and Gnathocharax as sister groups based on seven synapomorphies. Our approach demonstrates the importance of developmental studies to better understand morphological evolution of miniaturized, truncated taxa, and to generate hypotheses of their relationships.
Langecker, T G; Neumann, B; Hausberg, C; Parzefall, J
Epigean and blind cave-dwelling populations of the characid Astyanax fasciatus differ in their agonistic behavior. Epigean specimens are characterized by intense aggressive behavior and territoriality in the laboratory, whereas the blind cave fishes are rarely aggressive and have totally lost the territorial behavior. These behavioral changes are genetically based. In the present study, a comparative analysis of the optical releasers for aggressive behavior has been performed in both epigean and cave-dwelling populations. It was expected that the regression of aggressive behavior should be accompanied by the regression of the genetically fixed optical releasers for aggression in the cave specimens. For the analysis of cave fishes, well-eyed F1-hybrids of cave and epigean specimens (Pachon × Teapao) as well as phylogenetically young cave specimens (Micos) selected for large eyes, have been used. In epigean specimens, aggression is most intensely released by a combination of the signals 'natural shape' and 'locomotion'. The cave populations exhibit a partial regression of the releaser 'natural shape'. 'Locomotion', however, has become a more effective releaser for aggression in cave fishes than it has in their epigean relatives. The results are discussed with respect to their evolutionary significance.
Utsunomia, Ricardo; Silva, Duílio Mazzoni Zerbinato de Andrade; Ruiz-Ruano, Francisco J; Araya-Jaime, Cristian; Pansonato-Alves, José Carlos; Scacchetti, Priscilla Cardim; Hashimoto, Diogo Teruo; Oliveira, Claudio; Trifonov, Vladmir A; Porto-Foresti, Fábio; Camacho, Juan Pedro M; Foresti, Fausto
B chromosomes constitute a heterogeneous mixture of genomic parasites that are sometimes derived intraspecifically from the standard genome of the host species, but result from interspecific hybridization in other cases. The mode of origin determines the DNA content, with the B chromosomes showing high similarity with the A genome in the first case, but presenting higher similarity with a different species in the second. The characid fish Moenkhausia sanctaefilomenae harbours highly invasive B chromosomes, which are present in all populations analyzed to date in the Parana and Tietê rivers. To investigate the origin of these B chromosomes, we analyzed two natural populations: one carrying B chromosomes and the other lacking them, using a combination of molecular cytogenetic techniques, nucleotide sequence analysis and high-throughput sequencing (Illumina HiSeq2000). Our results showed that i) B chromosomes have not yet reached the Paranapanema River basin; ii) B chromosomes are mitotically unstable; iii) there are two types of B chromosomes, the most frequent of which is lightly C-banded (similar to euchromatin in A chromosomes) (B1), while the other is darkly C-banded (heterochromatin-like) (B2); iv) the two B types contain the same tandem repeat DNA sequences (18S ribosomal DNA, H3 histone genes, MS3 and MS7 satellite DNA), with a higher content of 18S rDNA in the heterochromatic variant; v) all of these repetitive DNAs are present together only in the paracentromeric region of autosome pair no. 6, suggesting that the B chromosomes are derived from this A chromosome; vi) the two B chromosome variants show MS3 sequences that are highly divergent from each other and from the 0B genome, although the B2-derived sequences exhibit higher similarity with the 0B genome (this suggests an independent origin of the two B variants, with the less frequent, B2 type presumably being younger); and vii) the dN/dS ratio for the H3.2 histone gene is almost 4-6 times higher for B chromosomes than for A chromosome sequences, suggesting that purifying selection is relaxed for the DNA sequences located on the B chromosomes, presumably because they are mostly inactive.
de A Silva, Duílio M Z; Daniel, Sandro Natal; Camacho, Juan Pedro M; Utsunomia, Ricardo; Ruiz-Ruano, Francisco J; Penitente, Manolo; Pansonato-Alves, José Carlos; Hashimoto, Diogo Teruo; Oliveira, Claudio; Porto-Foresti, Fábio; Foresti, Fausto
Eukaryote genomes are frequently burdened with the presence of supernumerary (B) chromosomes. Their origin is frequently investigated by chromosome painting, under the hypothesis that sharing the repetitive DNA sequences contained in the painting probes is a sign of common descent. However, the intragenomic mobility of many anonymous DNA sequences contained in these probes (e.g., transposable elements) adds high uncertainty to this conclusion. Here we test the validity of chromosome painting to investigate B chromosome origin by comparing its results for seven B chromosome types in two fish species genus Astyanax, with those obtained (1) by means of the physical mapping of 18S ribosomal DNA (rDNA), H1 histone genes, the As51 satellite DNA and the (AC)15 microsatellite, and (2) by comparing the nucleotide sequence of one of these families (ITS regions from ribosomal DNA) between genomic DNA from B-lacking individuals in both species and the microdissected DNA from two metacentric B chromosomes found in these same species. Intra- and inter-specific painting suggested that all B chromosomes that were assayed shared homologous DNA sequences among them, as well as with a variable number of A chromosomes in each species. This finding would be consistent with a common origin for all seven B chromosomes analyzed. By contrast, the physical mapping of repetitive DNA sequences failed to give support to this hypothesis, as no more than two B-types shared a given repetitive DNA. Finally, sequence analysis of the ITS regions suggested that at least some of the B chromosomes could have had a common origin.
Utsunomia, Ricardo; Silva, Duílio Mazzoni Zerbinato de Andrade; Ruiz-Ruano, Francisco J.; Araya-Jaime, Cristian; Pansonato-Alves, José Carlos; Scacchetti, Priscilla Cardim; Hashimoto, Diogo Teruo; Oliveira, Claudio; Trifonov, Vladmir A.; Porto-Foresti, Fábio; Camacho, Juan Pedro M.; Foresti, Fausto
B chromosomes constitute a heterogeneous mixture of genomic parasites that are sometimes derived intraspecifically from the standard genome of the host species, but result from interspecific hybridization in other cases. The mode of origin determines the DNA content, with the B chromosomes showing high similarity with the A genome in the first case, but presenting higher similarity with a different species in the second. The characid fish Moenkhausia sanctaefilomenae harbours highly invasive B chromosomes, which are present in all populations analyzed to date in the Parana and Tietê rivers. To investigate the origin of these B chromosomes, we analyzed two natural populations: one carrying B chromosomes and the other lacking them, using a combination of molecular cytogenetic techniques, nucleotide sequence analysis and high-throughput sequencing (Illumina HiSeq2000). Our results showed that i) B chromosomes have not yet reached the Paranapanema River basin; ii) B chromosomes are mitotically unstable; iii) there are two types of B chromosomes, the most frequent of which is lightly C-banded (similar to euchromatin in A chromosomes) (B1), while the other is darkly C-banded (heterochromatin-like) (B2); iv) the two B types contain the same tandem repeat DNA sequences (18S ribosomal DNA, H3 histone genes, MS3 and MS7 satellite DNA), with a higher content of 18S rDNA in the heterochromatic variant; v) all of these repetitive DNAs are present together only in the paracentromeric region of autosome pair no. 6, suggesting that the B chromosomes are derived from this A chromosome; vi) the two B chromosome variants show MS3 sequences that are highly divergent from each other and from the 0B genome, although the B2-derived sequences exhibit higher similarity with the 0B genome (this suggests an independent origin of the two B variants, with the less frequent, B2 type presumably being younger); and vii) the dN/dS ratio for the H3.2 histone gene is almost 4–6 times higher for B chromosomes than for A chromosome sequences, suggesting that purifying selection is relaxed for the DNA sequences located on the B chromosomes, presumably because they are mostly inactive. PMID:26934481
Barbosa, Patrícia; de Oliveira, Luiz Antonio; Pucci, Marcela Baer; Santos, Mateus Henrique; Moreira-Filho, Orlando; Vicari, Marcelo Ricardo; Nogaroto, Viviane; de Almeida, Mara Cristina; Artoni, Roberto Ferreira
Most part of the eukaryotic genome is composed of repeated sequences or multiple copies of DNA, which were considered as "junk DNA", and may be associated to the heterochromatin. In this study, three populations of Astyanax aff. scabripinnis from Brazilian rivers of Guaratinguetá and Pindamonhangaba (São Paulo) and a population from Maringá (Paraná) were analyzed concerning the localization of the nucleolar organizer regions (Ag-NORs), the As51 satellite DNA, the 18S ribosomal DNA (rDNA), and the 5S rDNA. Repeated sequences were also isolated and identified by the Cot - 1 method, which indicated similarity (90%) with the LINE UnaL2 retrotransposon. The fluorescence in situ hybridization (FISH) showed the retrotransposon dispersed and more concentrated markers in centromeric and telomeric chromosomal regions. These sequences were co-localized and interspaced with 18S and 5S rDNA and As51, confirmed by fiber-FISH essay. The B chromosome found in these populations pointed to a conspicuous hybridization with LINE probe, which is also co-located in As51 sequences. The NORs were active at unique sites of a homologous pair in the three populations. There were no evidences that transposable elements and repetitive DNA had influence in the transcriptional regulation of ribosomal genes in our analyses.
Lopes, F P; Pereira, B F; Alves, R M S; Valim, J R T; Figueiredo, F A T; Pitol, D L; Caetano, F H
Most water bodies in Brazil, and in the world, are contaminated by some types of pollutants, ranging from sewage to metal/chemicals, carcinogenic products, and biodegradable detergents. Despite the extensive knowledge on their effects on fish biology and especially on gill morphology, research that concerns their impacts on gill rakers and implications in parameters such as food consumption cannot be found in the literature. Gill rakers are vital because, together with gills, they are responsible for the defense and protection of the organism and for selecting appropriate food for survival. When detergents, which can act as toxic chemical agents, get in contact with the body of the fish, they can cause severe effects that must be understood. Therefore, our study investigated ultramorphological changes in gill rakers of Astyanax altiparanae (Lambeth) caused by the exposure to biodegradable detergents. Fish were exposed to a 1 mg/L dilution of a mixture of detergents and pure water from an artesian well for 5 months. Results revealed that the first month of exposure to detergent caused dilation of chemical receptors in taste buds and the rise of a large number of orifices for mucus release among pavement cells in gill rakers, although only a small amount of mucus was found in fish exposed both to pure water and the detergent dilution. After 5 months, there was an increase in the dilation of these chemoreceptors, excess mucus on gill rakers of detergent groups, and the emergence of microbridges between microridges in pavement cells.
Leknes, I L
Histochemical properties of goblet cells in intestine of a stomach-less teleost, tiger barb (Puntius tetrazona), and a stomach-containing teleost, black tetra (Gymnocorymbus ternetzi), are described and compared. The intestine goblet cells were mostly wide in both species, but in tiger barb, some of them were markedly thinner. In black tetra, all the intestine goblet cells displayed magenta colour after PAS, whereas in the tiger barb, only the thinner goblet cells displayed such affinity. The latter cell type was coloured strongly magenta when the tissue was treated with alcian blue (pH 2.5) followed by PAS, whereas the wide goblet cells in tiger barb and all goblet cells in black tetra displayed mainly a blue colour after such treatment. Further, the goblet cells in both species were coloured cleanly blue after high iron diamine followed by alcian blue (pH 2.5). The intestine goblet cells in both species displayed a moderate affinity to WGA and concanavalin A lectins and no affinity to DBA. Most of the goblet cells displayed no affinity to PNA, but some of them in the tiger barb displayed a moderate or strong affinity to this lectin. The affinity to WGA was somewhat strengthened after pre-treatment with neuraminidase. These results suggest that tiger barb contains two types or variants of intestinal goblet cells: high numbers of wide cells filled by acidic, non-sulphated mucin and some thinner cells filled by neutral mucin. The intestine goblet cells in black tetra were filled by variable amounts of neutral and acidic mucin, but the total number of such cells is much less than in tiger barb. The present lectin and neuraminidase results suggest that the intestinal mucins in both species contain significant amounts of N-acetylglucosamine, sialic acid and glucose/mannose, but seem to lack N-acetylgalactosamine. However, some of these cells in tiger barb contain moderate to large amounts of galactose. Together, these results suggest significant species-specific features of the intestine goblet cells and mucin types in tiger barb and black tetra. In conclusion, the present results suggest that the diet and feeding habits in stomach-less teleosts compared with stomach-containing teleosts, greatly influence the number of intestine goblet cells and type of mucin in these cells.
Four populations of Astyanax hastatus Myers 1928 from the Guapimirim River basin (Rio de Janeiro State) were analyzed and three distinct cytotypes identified. These cytotypes presented 2n = 50 chromosomes, with 4M+8SM+10ST+28A (Cytotype A), 8M+10SM+14ST+18A (Cytotype B), 6M+8SM+4ST+32A (Cytotype C) and scanty heterochromatin, mainly located throughout pericentromeric regions of several chromosomal pairs. No homologies with the As-51 satellite DNA were observed in the three cytotypes, although all of them presented multiple 18S rDNA sites, as detected by both silver nitrate staining and FISH (fluorescent in situ hybridization). The application of the term “species complex” in Astyanax is discussed from a cytotaxonomic viewpoint. PMID:21637509
Vieira, Vanessa A R O; Correia, Tiago G; Moreira, Renata G
We investigated the effects of acidic pH and acute aluminum (Al) exposure on the metabolic substrates of Astyanax bimaculatus, and on the ability of these animals to recover in clean water. After an acclimation period, sexually mature A. bimaculatus females were sorted into six glass aquaria with three experimental groups: control in neutral pH (7.0), acidic pH (5.5), and Al (0.5 mg·L(-1)) in acidic pH (5.5). After a 96 h treatment, 10 animals from each experimental group were sampled and the rest were returned to clean water in neutral pH without Al for a recovery period of 96 h. The acidic pH, either alone or combined with Al, decreased T4 levels, whereas Al exposure increased T3 levels. Recovery of T3 levels occurred after 96 h. Al exposure decreased ovary and plasma proteins, muscle glycogen contents, and hepatic lipids due to lipoperoxidation. In the recovery phase, lipids decreased in most tissues, probably to re-establish ovary protein and hepatic glycogen. A. bimaculatus prioritized the use of energetic resources during acclimatization to Al instead of prioritizing reproduction, thereby avoiding the ovulation of impaired eggs.
Castro Paz, Francis Paola; Batista, Jacqueline da Silva; Porto, Jorge Ivan Rebelo
DNA barcoding can be an effective tool for fast and accurate species-level identification based on sequencing of the mitochondrial cytochrome c oxidase subunit (COI) gene. The diversity of this fragment can be used to estimate the richness of the respective species. In this study, we explored the use of DNA barcoding in a group of ornamental freshwater fish of the genus Hyphessobrycon. We sequenced the COI from 10 species of Hyphessobrycon belonging to the “Rosy Tetra Clade” collected from the Amazon and Negro River basins and combined our results with published data. The average conspecific and congeneric Kimura 2-parameter distances were 2.3% and 19.3%, respectively. Six of the 10 species were easily distinguishable by DNA barcoding (H. bentosi, H. copelandi, H. eques, H. epicharis, H. pulchrippinis, and H. sweglesi), whereas the remaining species (H. erythrostigma, H. pyrrhonotus, H. rosaceus and H. socolofi) lacked reciprocal monophyly. Although the COI gene was not fully diagnostic, the discovery of distinct evolutionary units in certain Hyphessobrycon species under the same specific epithet as well as haplotype sharing between different species suggest that DNA barcoding is useful for species identification in this speciose genus. PMID:24878569
Studies of genotoxicity in fish caused by cyanobacterial microcystins can be useful both in determining the sensitivity of native species, as well as comparing exposure routes. The genotoxicity caused by the microcystins LR and LA from a bloom collected in a eutrophic lake, was revealed in the fish Astyanaxbimaculatus, a native species from South America. LC50 (72 h) was determined as 242.81 μg L -1 and LD50 (72 h) as 49.19 μg kg -1 bw. There was a significant increase of DNA damage in peripheral erythrocytes, following intraperitoneal injection (ip) with tested concentrations of 24.58 μg kg -1 bw and 36.88 μg kg -1 bw, as well as through body exposure to a concentration of 103.72 μg L -1 . Micronucleus (MN) induction was observed after ip injections of 24.58 μg kg -1 bw and 36.88 μg kg -1 bw for 72 h, as well as following body exposure for 72 at 103.72 μg L -1 . Thus, both exposure routes resulted in MN induction and DNA damage. Apoptosis-necrosis testing was carried out only by ip injection with concentrations of 24.58 μg kg -1 bw and 36.88 μg kg- 1 bw. Exposure to microcystins at lower concentrations induced more apoptosis than necrosis in peripheral erythrocytes, whereas exposure at higher concentrations gave rise to both conditions. Thus, Astyanax bimaculatus can be considered as a species sensitive to the genotoxic effects caused by microcystins. PMID:21637586
Román-Valencia, César; Ruiz-C, Raquel I; Taphorn, Donald C; Mancera-Rodriguez, Néstor J; García-Alzate, Carlos A
Fish biodiversity of aquatic ecosystems is highly threatened by different economic activities driven by human populations, and its description is increasingly a priority. For the Cauca-Magdalena River system we have described 14 species, and the purpose of this paper was to describe three new species belonging to the same genus Hemibrycon from the Nare and Guatapé River drainages of the middle Magdalena River, Colombia. The description was based on a series of 200 specimens, and the use of morphometric, meristic and osteological characters, as well as fish distribution and morphogeometric analytical methods. We have found that Hemibrycon fasciatus n. sp. (n = 54) differs from other species of Hemibrycon (that also have a vertical humeral spot) in having: melanophores outlining the posterior margins of the scales along sides of body; humeral spot extending onto posterior margin of opercle; a dark lateral stripe, formed by deep pigment that is continuous with the peduncular spot; the toothed portion of the maxilla not reaching the dorsal margin of the dentary (vs. toothed portion of maxilla extending beyond dorsal margin of dentary); all maxillary teeth tricuspid (vs. some unicuspid teeth present on maxilla). H. cardalensis n. sp. (n = 64) differs in having: a vertically elongate humeral spot that extends one or two scales below the lateral line canal. H. cardalensis n. sp. differs from all congeners in having the pigment of the caudal spot restricted to the ventral half of the caudal peduncle, and in having melanophores around the anterior scales of the lateral line. Hemibrycon antioquiae n. sp. (n = 82) differs in having a circular humeral spot. It differs from the other species with a circular humeral spot, like H. mikrostiktos, in having a projection of disperse melanophores extending from the dorsal margin of the humeral spot to below the lateral stripe. Habitat data and environmental impacts caused by the construction of reservoirs for hydroelectric projects and other threats in the area are included, as well as a key to all species Hemibrycon present in the Magdalena River Basin. The synonymy of H. pautensis with H. polyodon is discussed and H. pautensis is revalidated.
Piscor, Diovani; Parise-Maltempi, Patricia P
The organization of microsatellites in B and sex chromosomes has been linked to chromosomal evolution in a number of animal groups. Here, the chromosomal organizations of (CA)15, (GA)15, (CG)15, (GACA)4, and (GATA)8 microsatellites were examined in several Astyanax species with different diploid numbers: Astyanax mexicanus (2n = 50 + 1 B chromosome), A. altiparanae (2n = 50), A. marionae (2n = 48), A. fasciatus (2n = 46), and A. schubarti (2n = 36). The (CA)15 and (GA)15 microsatellites were dispersed across the chromosomes of A. altiparanae and A. fasciatus but were also observed as clusters (CA and GA for A. altiparanae, and CA for A. fasciatus). In A. marionae and A. schubarti, the (CA)15 and (GA)15 microsatellites were dispersed but were also observed as clustered signals and coincident with heterochromatic regions. In all 4 of these species, the (CG)15 and (GACA)4 microsatellites were dispersed across chromosomes, and the (GATA)8 microsatellite was co-localized with 5S rDNA. In A. mexicanus, the (CA)15, (GA)15, (CG)15, (GATA)8, and (GACA)4 microsatellites were weakly detected and dispersed across the chromosomes of the A complement. On the B chromosome, signals for the different microsatellites were weak, strong, absent, weak, and absent, respectively. The distribution of microsatellites and the locational relationship between microsatellites and 5S rDNA are discussed, and a possible evolutionary pathway is proposed for microsatellites in Astyanax.
Román-Valencia, César; Ruiz-C, Raquel I.; Taphorn, Donald C.; García-Alzate, Carlos A.
Abstract Hemibrycon sanjuanensis, new species, is described from the upper San Juan River drainage, Pacific versant, Colombia. It is distinguished from Hemibrycon boquiae, Hemibrycon brevispini, Hemibrycon cairoense, Hemibrycon colombianus, Hemibrycon mikrostiktos, Hemibrycon metae, Hemibrycon palomae, Hemibrycon rafaelense and Hemibrycon tridens by the presence of a circular or oblong humeral spot that is located two scales posterior to the opercle (vs. 3–4 scales in Hemibrycon palomae, Hemibrycon rafaelense, Hemibrycon brevispini and Hemibrycon cairoense, and 0–1 scales, in Hemibrycon metae and Hemibrycon boquiae). It further differs from Hemibrycon colombianus in having a round or oblong humeral spot (vs. rectangular). It differs from Hemibrycon beni, Hemibrycon dariensis, Hemibrycon divisorensis, Hemibrycon helleri, Hemibrycon huambonicus, Hemibrycon inambari, Hemibrycon jabonero, Hemibrycon jelskii, Hemibrycon mikrostiktos, Hemibrycon polyodon, Hemibrycon quindos, Hemibrycon raqueliae, Hemibrycon santamartae, Hemibrycon surinamensis, Hemibrycon taeniurus, Hemibrycon tridens, and Hemibrycon yacopiae in having melanophores on the posterior margins of the scales along the sides of body (vs. lacking melanophores on margins of scales along entire length of the sides of body). The new species differs from all congeners mentioned above in having, among other features, six teeth in the outer premaxillary row arranged in a straight line (vs. five or fewer teeth not arranged in straight line except Hemibrycon cairoense with two to six teeth in the outer premaxillary row). PMID:25493068
Román-Valencia, César; Ruiz-C, Raquel I; Taphorn, Donald C; García-Alzate, Carlos A
Hemibryconsanjuanensis, new species, is described from the upper San Juan River drainage, Pacific versant, Colombia. It is distinguished from Hemibryconboquiae, Hemibryconbrevispini, Hemibryconcairoense, Hemibryconcolombianus, Hemibryconmikrostiktos, Hemibryconmetae, Hemibryconpalomae, Hemibryconrafaelense and Hemibrycontridens by the presence of a circular or oblong humeral spot that is located two scales posterior to the opercle (vs. 3-4 scales in Hemibryconpalomae, Hemibryconrafaelense, Hemibryconbrevispini and Hemibryconcairoense, and 0-1 scales, in Hemibryconmetae and Hemibryconboquiae). It further differs from Hemibryconcolombianus in having a round or oblong humeral spot (vs. rectangular). It differs from Hemibryconbeni, Hemibrycondariensis, Hemibrycondivisorensis, Hemibryconhelleri, Hemibryconhuambonicus, Hemibryconinambari, Hemibryconjabonero, Hemibryconjelskii, Hemibryconmikrostiktos, Hemibryconpolyodon, Hemibryconquindos, Hemibryconraqueliae, Hemibryconsantamartae, Hemibryconsurinamensis, Hemibrycontaeniurus, Hemibrycontridens, and Hemibryconyacopiae in having melanophores on the posterior margins of the scales along the sides of body (vs. lacking melanophores on margins of scales along entire length of the sides of body). The new species differs from all congeners mentioned above in having, among other features, six teeth in the outer premaxillary row arranged in a straight line (vs. five or fewer teeth not arranged in straight line except Hemibryconcairoense with two to six teeth in the outer premaxillary row).
Tavares-Dias, M; Moraes, F R
Morphological, cytochemical and ultrastructural studies are important to demonstrate the function of the blood cells, which is very little understood in teleosts. In peripheral blood of 'piracanjuba' Brycon orbignyanus, thrombocytes, lymphocytes, monocytes, neutrophils and heterophils were studied and characterized. Thrombocytes had a fusiform or oval shape with PAS-positive granules. Lymphocytes presented small size with sparse basophilic cytoplasm. Monocytes were large in size, presented basophilic cytoplasm that may be foamy or vacuolated, with non-specific esterase staining. The neutrophils presented lightly neutrophilic granule cytoplasm, with positivity for PAS and peroxidase. The heterophils were large in size, with eosinophilic and basophilic granules cytoplasm and PAS-positive. Transmission electron microscopy study demonstrated that the thrombocytes, lymphocytes and monocytes features were similar to other teleosts. In ultrastructural study only one type of neutrophils was observed. Cytochemical findings indicated that neutrophils and monocytes of B. orbignyanus may be involved in phagocytosis, and neutrophils play an important microbicidal role.
Almirón, Adriana; Casciotta, Jorge; Piálek, Lubomír; Doubnerová, Klára; Říčan, Oldřich
Oligosarcus amome is described from tributaries of the arroyo Yabotí-Guazú, río Uruguay basin, Misiones Province, Argentina. This new species can be distinguished from all its congeners by the following combination of characters: presence of two conspicuous series of teeth on premaxilla bearing pentacuspidate teeth in the outer series. Oligosarcus amome is the sister taxon of all remaining analyzed species of the genus excepting O. itau.
Petrolli, Marina G; Benine, Ricardo C
From the examination of extensive comparative material currently identified as M. jamesi we verified that there are, at least, three new species under this name. These, along with M. jamesi and M. justae, form what we herein called the M. jamesi species complex, by sharing the following group of characters: a short maxilla, with its distal margin not exceeding anterior third of the second infraorbital; first through third teeth of the inner row of premaxilla and first and second dentary teeth with cusps arranged in a pronounced arch, humeral spot positioned between the fourth and seventh scales of the lateral line and extending up to four scale rows above the lateral line and one scale row below the lateral line, and a vertically oval to round spot at the base of the caudal fin rays. Moenkhausia ischyognatha sp. n., from Rio Xingu basin, differs from the other species of the complex by its lower head depth. Moenkhausia alesis sp. n., from the river system Tocantins-Araguaia, differs from M. jamesi, M. ischyognatha, and M. sthenosthoma by the number of scale rows above the lateral line. Moenkhausia sthenosthoma sp. n., from the Rio Madeira basin, differs from M. jamesi by the number of scale rows between the lateral line and the midventral scale series. Moenkhausia justae can be diagnosed from the other species of the complex by having a tri to pentacuspidate tooth on the maxilla.
Honji, Renato Massaaki; Nóbrega, Rafael Henrique; Pandolfi, Matias; Shimizu, Akio; Borella, Maria Inês; Moreira, Renata Guimarães
Freshwater fish that live exclusively in rivers are at particular risk from fragmentation of the aquatic system, mainly the species that migrate upriver for reproduction. That is the case of Salminus hilarii, an important migratory species currently classified as "almost threatened" in the São Paulo State (Brazil), facing water pollution, dam construction, riparian habitat destruction and environmental changes that are even more serious in this State. Additionally, this species show ovulation dysfunction in captivity. Our studies focused on the identification and distribution of the pituitary cell types in the adenohypophysis of S. hilarii females, including a morphometric analysis that compares pituitary cells from wild and captive broodstocks during the reproductive annual cycle. The morphology of adenohypophysial cells showed differences following the reproductive cycle and the environment. In general, optical density suggested a higher cellular activity during the previtellogenic (growth hormone) and vitellogenic (somatolactin) stages in both environments. Additionally, the nucleus/cell ratio analysis suggested that growth hormone and somatolactin cells were larger in wild than in captive females in most reproductive stages of the annual cycle. In contrast, prolactin hormone showed no variation throughout the reproductive cycle (in both environments). Morphometrical analyses related to reproduction of S. hilarii in different environmental conditions, suggest that somatolactin and growth hormone play an important role in reproduction in teleost and can be responsible for the regulation of associated processes that indirectly affect reproductive status.
Burchards, H; Dölle, A; Parzefall, J
The different populations have been tested for aggressive behaviour in groups of four to eight animals of both sexes in tanks ranging from 251 to 9501. In darkness less aggressive behaviour has been observed with the help of an infrared video-camera in the epigean fish and the eyed Micos cave fish. The strongest degree of reduction in aggressive behaviour is shown by the totally blind populations. The aggressiveness increases in the epigean fish as soon as space and food supply diminish.
Razo-Mendivil, Ulises; García-Vásquez, Adriana; Rubio-Godoy, Miguel
Over the course of one year, undescribed specimens of Gyrodactylus were recovered from banded tetra, Astyanax aeneus collected in the La Antigua and Nautla river basins in central Veracruz, Mexico. Parasites were processed for morphometric and molecular analyses. Morphometrically, Gyrodactylus samples collected in the La Antigua river had slightly smaller haptoral structures than those collected from the Nautla river. During the 12month-collection of samples, however, water temperature varied considerably (ca. 20°C to 30°C), and this abiotic factor is known to affect the size of gyrodactylid attachment structures. Moreover, no clear discrimination was possible between individual parasites collected from the two rivers based on the morphology of the marginal hook, which is recognised as a very informative character to discriminate between species. The morphology of the ventral bar, however, differed between specimens from both rivers: worms from Nautla all had long, rounded processes on the ventral bar, which formed a relatively closed angle with the dorsal edge of the bar proper, while most - but not all - specimens from La Antigua had comparatively slender processes forming a more open angle with respect to the ventral bar. Phylogenetic analyses based on the sequences of the ITS1, 5.8S rRNA gene, and ITS2 of gyrodactylids indicated the existence of two distinct, well-supported lineages whose sequences differ by >4%, one of which was only found in the Nautla basin, while the other was collected in both river systems. A posteriori, principal component analysis (PCA) of the morphometric data of sequenced specimens indicated that features of the dorsal bar, the hamuli and the ventral bar enable discrimination between the two phylogenetic lineages. Based on these independent sources of information (morphometric and molecular data), two new species of Gyrodactylus are described: Gyrodactyluspakan n. sp. and Gyrodactylusteken n. sp. The phylogenetic relationships of both new species to other gyrodactylids infecting characiformes (for which molecular data are available) are presented, which suggests that their closest relative is Gyrodactylus carolinae, a parasite of Characidium lanei in Brazil.
Galvan, Gabrieli L; Lirola, Juliana R; Felisbino, Karoline; Vicari, Taynah; Yamamoto, Carlos I; Cestari, Marta M
The sublethal effects of water-soluble fraction of gasoline (WSFG, 1.5 % v/v) were evaluated in the freshwater fish, Astynax altiparanae, after acute exposure (96 h) under a semi-static system. In addition, the recovery process was assessed in the fish following contaminant depuration. Recovery treatments were carried out with gradual depuration (GD), consisting of 7 days in the WSFG, followed by 8 days in clean water; and treatments with total depuration in clean water for 15 (DEP 15) and 30 days (DEP 30). The effects were evaluated through the piscine micronucleus test and by differential counting of organic defense cells. Acute exposure increased the frequency of neutrophils. In the GD treatment, the thrombocyte count and erythrocytic nuclear abnormalities (ENA) increased. In the DEP 15 treatment, there was a reduction of ENA; and following 30 days of depuration (i.e., DEP 30), the number of lymphocytes increased and the thrombocyte count remained high. These results indicate a long-term response to a condition of stress from WSFG.
Santos, Angélica Rossotti Dos; Usso, Mariana Campaner; Gouveia, Juceli Gonzalez; Araya-Jaime, Cristian; Frantine-Silva, Wilson; Giuliano-Caetano, Lucia; Foresti, Fausto; Dias, Ana Lúcia
The mapping of repetitive DNA sites by fluorescence in situ hybridization has been widely used for karyotype studies in different species of fish, especially when dealing with related species or even genera presenting high chromosome variability. This study analyzed three populations of Bryconamericus, with diploid number preserved, but with different karyotype formulae. Bryconamericus ecai, from the Forquetinha river/RS, presented three new cytotypes, increasing the number of karyotype forms to seven in this population. Other two populations of Bryconamericus sp. from the Vermelho stream/PR and Cambuta river/PR exhibited interpopulation variation. The chromosome mapping of rDNA sites revealed unique markings among the three populations, showing inter- and intrapopulation variability located in the terminal region. The molecular analysis using DNA barcoding complementing the cytogenetic analysis also showed differentiation among the three populations. The U2 small nuclear DNA repetitive sequence exhibited conserved features, being located in the interstitial region of a single chromosome pair. This is the first report on its occurrence in the genus Bryconamericus. Data obtained revealed a karyotype variability already assigned to the genus, along with polymorphism of ribosomal sites, demonstrating that this group of fish can be undergoing a divergent evolutionary process, constituting a substantive model for studies of chromosomal evolution.
Background Mesoamerica is one of the world's most complex biogeographical regions, mostly due to its complex geological history. This complexity has led to interesting biogeographical processes that have resulted in the current diversity and distribution of fauna in the region. The fish genus Astyanax represents a useful model to assess biogeographical hypotheses due to it being one of the most diverse and widely distributed freshwater fish species in the New World. We used mitochondrial and nuclear DNA to evaluate phylogenetic relationships within the genus in Mesoamerica, and to develop historical biogeographical hypotheses to explain its current distribution. Results Analysis of the entire mitochondrial cytochrome b (Cytb) gene in 208 individuals from 147 localities and of a subset of individuals for three mitochondrial genes (Cytb, 16 S, and COI) and a single nuclear gene (RAG1) yielded similar topologies, recovering six major groups with significant phylogeographic structure. Populations from North America and Upper Central America formed a monophyletic group, while Middle Central America showed evidence of rapid radiation with incompletely resolved relationships. Lower Central America lineages showed a fragmented structure, with geographically restricted taxa showing high levels of molecular divergence. All Bramocharax samples grouped with their sympatric Astyanax lineages (in some cases even with allopatric Astyanax populations), with less than 1% divergence between them. These results suggest a homoplasic nature to the trophic specializations associated with Bramocharax ecomorphs, which seem to have arisen independently in different Astyanax lineages. We observed higher taxonomic diversity compared to previous phylogenetic studies of the Astyanax genus. Colonization of Mesoamerica by Astyanax before the final closure of the Isthmus of Panama (3.3 Mya) explains the deep level of divergence detected in Lower Central America. The colonization of Upper Mesoamerica apparently occurred by two independent routes, with lineage turnover over a large part of the region. Conclusion Our results support multiple, independent origins of morphological traits in Astyanax, whereby the morphotype associated with Bramocharax represents a recurrent trophic adaptation. Molecular clock estimates indicate that Astyanax was present in Mesoamerica during the Miocene (~8 Mya), which implies the existence of an incipient land-bridge connecting South America and Central America before the final closure of the Isthmus of Panama (~3.3 Mya). PMID:19102731
Rivero-Wendt, C L G; Miranda-Vilela, A L; Ferreira, M F N; Borges, A M; Grisolia, C K
The synthetic hormone, 17-α-methyltestosterone (MT), is used in fish hatcheries to induce male monosex. Androgenic effects on various fish species have been reported; however, few studies have assessed possible genotoxic effects, although there are concerns about such effects in target and non-target species. We evaluated genotoxic and gonadal effects of MT in adult tilapia (Oreochromis niloticus) and Astyanax bimaculatus (a common native non-target fish in Brazil). Fish were fed for 28 days with ration containing MT (60 mg/L), a normal dose used in fish farming. Evaluation of MT genotoxicity was carried out through micronucleus test, nuclear abnormality, and comet assay analyses on peripheral erythrocyte cells collected by cardiac puncture. There were no significant differences in micronucleus frequencies and DNA damage in both species; however, MT caused cytogenetic toxicity in the non-target species, A. bimaculatus, with significantly increased erythrocyte nuclear abnormalities. Histopathological analyses of the female gonads of O. niloticus revealed that MT significantly inhibited the development of mature oocytes, while in A. bimaculatus it provoked significant inhibition of spermatozoa production. We concluded that discharge of fish-hatcheries water onto the surface of aquatic ecosystems should be avoided due to risks to reproduction of native species.
Ornelas-García, Claudia P; Bastir, Markus; Doadrio, Ignacio
Phenotypic variation is important for evolutionary processes because it can allow local adaptation, promote genetic segregation, and ultimately give rise to speciation. Lacustrine systems provide a unique opportunity to study the mechanisms by which sister species can co-occur by means of ecological segregation. The fish genus Astyanax is characterized by high levels of phenotypic variability, providing an excellent model for the study of local specialization. Here, we analyze the morphological specializations through geometric morphometrics of two sympatric species described as different genera: Bramocharax caballeroi endemic to Lake Catemaco, and the widely distributed Astyanax aeneus. Additionally, we assess the correlation between phenotypic and genetic structure, and the phylogenetic signal of morphological variation. We examined body size and shape variation in 196 individuals and analyzed mitochondrial cytochrome b sequences in 298 individuals. Our results confirm the striking morphological divergence among the sympatric characids. Differences between them were mainly found in the body depth and profile and orientation of the head, where B. caballeroi in contrast with the A. aeneus, presented a fusiform body and an upward mouth. Moreover, different growth trajectories were observed among morphotypes, suggesting that a heterochronic process could be involved in the diversification of our study system. Morphological differences did not correspond with the molecular differentiation, suggesting high levels of homoplasy among the lineages of B. caballeroi morphs.
Moreira, Renata Guimarães; Honji, Renato Massaaki; Melo, Renato Garcia; Narcizo, Amanda de Moraes; Amaral, Juliane Suzuki; Araújo, Ronaldo de Carvalho; Hilsdorf, Alexandre Wagner Silva
Potamodromous teleosts that require migration to reproduce show dysfunctions that block ovulation and spawning while in captivity. To understand the physiological basis of these reproductive dysfunctions, follicle-stimulating hormone b subunit (fshb) and luteinizing hormone b subunit (lhb) gene expression analyses by real-time quantitative PCR, together with measurements of estradiol (E 2), 17α-hydroxyprogesterone (17α-OHP) and 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DHP) levels, were carried out throughout the reproductive cycle of the potamodromous Salminus hilarii. The following reproductive stages were evaluated in captive and wild females: previtellogenic (PV), advanced maturation/mature (AM) and regression/spent (REG/SPENT). In the wild females, fshb expression decreased from the PV to the AM stage, and the opposite pattern was detected for E 2, which increased from the PV to the AM stage. fshb was expressed at lower levels in captive than in wild females, and this difference did not change during the reproductive cycle. lhb expression also increased from the PV to the AM stage in both groups, but the wild females at the AM and REG/SPENT stages showed higher lhb expression levels than the captive females. The concentrations of 17α-OHP did not change during the reproductive cycle, and the levels were higher in the captive than in the wild females at all reproductive stages. 17α,20β-DHP levels did not change between wild and captive females. However, in captive females, the transition from PV to AM stage was followed by an increase in 17α,20β-DHP levels. These data indicate that dysfunctions in the gonadotropins and steroids synthesis pathways cause the ovulation failure in captive S. hilarii.
Faustino, Francine; Nakaghi, Laura Satiko Okada; Neumann, Erika
Brycon gouldingi is an endemic species from Tocantins-Araguaia basin, used as a food source by riverine communities and relevant to aquaculture. Information about the initial morphology of B. gouldingi, a recently described species, is absent. In the present study, we analysed the fertilization and the embryonic development of this species based on light and scanning electron microscopy. After collection of adult specimens in Mortes River - Mato Grosso, Brazil, adaptation to captivity and induced spawning at Buriti Fishculture, Nova Mutum - Mato Grosso, Brazil, in December 2007 and January 2008, samples were collected at pre-defined periods from egg extrusion up to larval hatching, which occurred at 13.9 ± 0.06 h post-fertilization (hpf) in average. At the moment of extrusion, the eggs were slightly ovoid bearing a single micropyle per oocyte with a funnel-shaped micropyle canal and vestibule covered with longitudinal folds, typical of the genus Brycon. The embryonic development of B. gouldingi was characterized by six stages with distinct features: zygote (from fertilization up to formation of egg-cell); cleavage (cell divisions resulting in blastomeres, including the morula phase); blastula (several embryonic cells in a cup shape, without distinction of cell boundaries); gastrula (cell movement); histogenesis/organogenesis (formation of tissues and organs); and hatching (larval chorion rupture). Right after hatching, the larvae presented neither swimming abilities nor visual accuracy, and the digestive trait was undifferentiated. The present study is the first report on biological features of embryogenesis in B. gouldingi, providing relevant information to several approaches, mainly related to taxonomy, ecology, conservation and captive rearing of this new Brycon species.
Santos, Paulo Henrique Nascimento; Tavares-Dias, Marcos
This study was the first investigation on the parasites of Triportheus rotundatus, a Characiformes fish from the Amazon, in Brazil. All the fish collected (100%) in a tributary from the Amazon River system were infected by one or more parasite species. The mean species richness of parasites was 4.9 ± 0.9, the Brillouin index was 0.39 ± 0.16, the evenness was 0.24 ± 0.09 and the Berger-Parker dominance was 0.81 ± 0.13. A total of 1316 metazoan parasites were collected, including Anacanthorus pithophallus, Anacanthorus furculus, Ancistrohaptor sp. (Dactylogyridae), Genarchella genarchella (Derogenidae), Posthodiplostomum sp. (Diplostomidae), Procamallanus (Spirocamallanus) inopinatus (Camallanidae), Echinorhynchus paranensis (Echinorhynchidae) and Ergasilus sp. (Ergasilidae), but monogenoideans were the dominant parasites. These parasites presented an aggregate dispersion pattern, except for P. (S.) inopinatus, which showed a random dispersion pattern. The body conditions of the hosts were not affected by the parasitism levels. This first report of these parasites for T. rotundatus indicates that the presence of ectoparasites and endoparasites was due to hosts behavior and availability of infective stages in the environment, and this was discussed.
Angulo, Arturo; Gracian-Negrete, Jatziry Marlene
A new species of Brycon is described from the Atlantic slope of Nicaragua and Costa Rica. Brycon costaricensis n. sp. differs from all other Central American Brycon species by the following combination of characters: 49 to 54 scales in the lateral line; 5 or 6 rows of scales between lateral line and pectoral fin base; 9 to 11 rows of scales between lateral line and dorsal fin base; 5 to 7 rows of scales between lateral line and anal fin base; anal fin notably longer than head, with 33 to 37 total rays; and a elongated and shallow caudal peduncle, whose length is 1.78 to 2.35 times its depth. A key to lower Mesoamerican species of the genus is also presented.
Ohara, Willian Massaharu; Mirande, Juan Marcos; de Lima, Flávio Cesar Thadeo
A new genus and species of characid fish is described from rio Braço Norte, a tributary of rio Teles Pires, Tapajós basin, Mato Groso, Brazil. The new taxa can be diagnosed from the remaining characids by a unique combination of characters that includes the presence of a single row of relatively compressed premaxillary teeth, large teeth with four to nine cusps on premaxillary and dentary, absence of pseudotympanum, incomplete lateral line with 7–13 pored scales, sexually-dimorphic males with distal margin of anal fin approximately straight, and presence of a nearly triangular and horizontally elongated blotch from the posterior half of the body to caudal peduncle. The most parsimonious phylogenetic hypothesis, using morphological data, recovered the new genus and species in a clade including Paracheirodon axelrodi and Hyphessobrycon elachys. PMID:28199336
Garcia-Alzate, Carlos A; Romin-Valencia, César; Ortega, Hernán
Hyphessobrycon with 129 valid species, is a genus of fish that has a great diversity of species in the Neotropical ichthyofauna, reaches its greatest diversity in the Amazon basin with about 70% of these species, is highly desired by hobbyists because of their beauty and color, and are still meeting new species. We analyzed specimens from the Departamento de Ictiología, Museo de Historia Natural de la Universidad Mayor de San Marcos, Lima, Perú (MUSM); and measurements of the specimens were taken point to point with digital calipers. Observations of bone and cartilage structures were made on cleared and stained (C&S) samples. The morphometric relationships between species using 21 variables were explored using a principal component analysis (PCA). Here we describe two new species, Hyphessobrycon taphorni and H. eschwartzae from the Madre de Dios River drainage, Peru. Hyphessobrycon taphorni sp. n. can be distinguished by the number of dorsal-fin rays (iii, 8), by the number of: pored lateral-line scales (4-5), teeth in the outer premaxillary row (1-2), teeth in the inner premaxillary row (7-8), by: the caudal-peduncle length (11.4-16.4% SL), number of lateral scales (28-29, except from H. loretoensis which has 29-30) and absence of a humeral spot (vs. present), it differs from H. loretoensis by the number of: scales between the lateral line and the anal fin origin (4 vs. 3) and maxillary teeth (2 vs. 3-4), and it differs from H. agulha by the number of branched pectoral-fin rays (11-12 vs. 9-10). Hyphessobrycon eschwartzae sp. n. is distinguished by the number of: simple anal-fin rays (iv), teeth on the dentary (13-15), teeth in the inner premaxillary row (6), teeth in the outer premaxillary row (3, except from H. heterorhabdus and H. loretoensis which have 3-4); it differs from H. loretoensis by the number of: pored lateral-line scales (7 vs. 9-10), scales between the lateral line and the dorsal-fin origin (5 vs. 3-4); it differs from H. agulha in the number of lateral scales (30-31 vs. 33-34), by the number of: predorsal scales (9 vs. 10), maxillary teeth (4 vs. 0-1); in having in life a red lateral stripe above the dark lateral stripe that extends from the posterior part of the opercle to the caudal peduncle (vs. absent) and by the presence of bony hooks in mature males only on the anal fin (vs. hooks on all fins, including the caudal).
Teixeira, T F; Netto-Ferreira, A L; Birindelli, J L O; Sousa, L M
Two new species of Hyphessobrycon are described from the headwaters of the Tapajós and Xingu River basins, Pará, Brazil. Both new species can be distinguished from congeners by the presence of a vertically elongate humeral blotch, a conspicuous round to vertically oblong caudal-peduncle blotch not extending onto the distal portions of the middle caudal-fin rays, a conspicuous blotch on the central portion of the third infraorbital immediately ventral to the eye, the lack of a conspicuous longitudinal stripe and the lack of sexual dimorphism in the extension of the caudal-peduncle blotch. Hyphessobrycon delimai n. sp. can be distinguished from Hyphessobrycon krenakore n. sp. by the extent of the caudal-peduncle blotch which extends across most of the caudal-peduncle depth (v. restricted to the middle portion of the caudal peduncle), the presence of dark chromatophores uniformly scattered along the length of the interradial membranes of the dorsal, anal and caudal fins (v. concentrated on the distal one-half or one-fourth of the interradial membranes) and the absence of small bony processes on the pelvic and anal fins of mature males (v. small bony processes present).
Black spot disease is common in freshwater fish and is usually caused by the metacercaria stage of digenetic trematodes, normally from the Diplostomidae family. The present study evaluated the prevalence and intensity of this disease in Astyanax aff. fasciatus (Teleostei: Characiformes) in the Guaíba Lake basin (RS, Brazil), including body parts assessment and the points of sampling with higher occurrence of black spots. Fish samples were taken seasonally from December 2002 until October 2004. The samples were collected with the use of a seine net at eleven points. The specimens were fixed in 10% formalin and stored in 70% ethanol. Black spot disease showed a low frequency in the Guaíba lake basin (2.07%) and no specificity to the species Astyanax aff. fasciatus was observed. A high prevalence among the individuals and high intensity of infection levels was found in the ventral and dorsal regions in relation to other body parts (e.g., pectoral, pelvic and anal regions). Among the sampling points studied, we observed a higher prevalence on samples collected at points Gasômetro, Saco da Alemoa and Sinos, located in open areas with less occurrence of mollusks.
Marcon, Lucas; Lopes, Diego Senra; Mounteer, Ann Honor; Goulart, Amara Manarino Andrade; Leandro, Mila Vasques; Dos Anjos Benjamin, Laércio
Female individuals of Hyphessobrycon eques were exposed to Diflubenzuron (Dimilin(®)) in order to determine whether exposure to sublethal levels of this insecticide causes changes in gill morphology. Fish were exposed to 0.01, 0.1 and 1.0mgL(-1) for 96h and 17 days and then submitted to pathological and histometric evaluation. Pathological lesions, such as hyperplasia, lamellar fusion, vascular congestion, secondary lamellar disarray, vasodilatation, hemorrhage and increased lamellar epithelium, were significantly more common in the gills of fish exposed to Dimilin(®) than the control. Histometric analysis documented significant changes in blood vessel diameter, primary lamellae width and secondary lamellae length, and the appearance of hemorrhage foci in all concentrations tested. Even at low Dimilin(®) concentrations, the histopathological alteration index was mild to moderate, thereby indicating that the function of this tissue was compromised. These findings indicate that indiscriminate use of Dimilin(®) can adversely affect the structural integrity of the gills of H. eques, which can cause numerous problems for fish farming systems.
Hurtado-Alarcón, Julio César; Mancera-Rodríguez, Néstor J; Saldamando-Benjumea, Clara I
Brycon henni is a native species in Magdalena's River basin, and because of its cultural and economic importance, is strongly overexploited. This study aimed to describe the genetic variability and population structure of this species from Nare and Guatapé rivers basins. A total of 195 individuals were collected and DNA extractions were obtained from muscle and blood tissue. Fourteen primers were evaluated with the RAPD technique, being four of them polymorphic, and produced 66 different fragments (63% polymorphism). Besides, using the molecular variance (AMOVA) analysis, the population structure was described for all sites (phi(ST) = 0.297, phi(ST) = 0.163; Nare and Guatapé river basins, respectively), and suggested the importance of the migratory behaviour of the species in the genetic differentiation. Genetic distances among sampled sites showed that most of the genetic differentiation occurred between sites Guatapé and El Cardal with respect to the others. A Mantel Test demonstrated a correlation between genetic and geographic distances (r = 0.431 both of the basins evaluated; r = 0.377, Nare river middle basin), and suggested isolation by distance. The outcomes obtained in this study have valuable implications in species conservation and the genetic variability of natural populations of B. henni, and should be complemented with morphological analyses.
Schalch, Ergio H C; de Moraes, Flávio R; de Moraes, Julieta R E
This work described the lesions caused in different species of fish by gill parasites from fee-fishing at Guariba, State of São Paulo. The research was developed from april, 1997 to march to 1999, seeking to verified the kind tissues lesions from fish. Of these, forty and seven were Leporinus macrocephalus and fifty and five Piaractus mesopotamicus. About 87.2% of the L. macrocephalus, and 58.1% of the P. mesopotamicus were sponged by several species of parasites. The parasite most abundant in L. macrocephalus was Piscinoodinium pillulare, while monogenean, Trichodina sp and myxosporidian infected P. mesopotamicus. Severe gill lesions have been observed in L. macrocephalus and P. mesopotamicus caused by monogenean, P. pillulare e Trichodina sp. parasitism, such as intersticial hemorrhage, sub-epithelium edema, inflammation, epitelial hiperplasy in filaments and lamina, proliferation of mucosal cells and laminar fusion.
Costa-Pereira, R; Paiva, F; Tavares, L E R
In July 2009 and July 2010 (two dry periods separated by an atypically large flood in the Pantanal wetland of Brazil), 34 and 33 specimens of the sardine fish Triportheus nematurus were collected, respectively, for the study of the metazoan parasite community of this species. Parasite ecological and community descriptors were calculated for both host samples, and possible similarities were tested statistically. Five species of metazoan parasites were identified, four of which were common to both host samples. A total of 61 metazoan parasites were collected from all fish hosts (17 specimens in July 2009 (mean: 0.5 ± 0.66 parasites/fish) and 44 specimens in July 2010 (mean: 1.33 ± 1.41 parasites/fish)). The nematode Procamallanus hilarii and the monogenean Anacanthorus sp. were the most prevalent and abundant species in 2009 and 2010, respectively. The mean total abundance and species richness were significantly higher in 2010. Parasite communities in both samples of T. nematurus were characterized by species with low prevalence, abundance, mean total abundance and species richness, thus indicating low parasite diversity. Significant differences in the prevalence and abundance of P. hilarii and Anacanthorus sp. between the two samples allowed the discrimination of infracommunities, which were united in two distinct groups. This appears to be the first evidence that the peculiar hydrological dynamics of the southern Pantanal wetland (Brazil) exert an important influence over the structure of the parasite community.
Ohara, Willian M; Lima, Flávio C T; Barros, Bruno S
A new species of Hyphessobrycon is described from the rio Roosevelt, rio Madeira basin, Mato Grosso State, Brazil. Hyphessobrycon petricolus sp. n. can be distinguished from its congeners by the unique combination of the following features: a well-defined, relatively narrow dark midlateral stripe on body extending from immediately behind posterior margin of opercle to the middle caudal-fin rays, relatively conspicuous humeral blotch, and 16-20 branched anal-fin rays. Comments on the remaining Hyphessobrycon species presenting a conspicuous dark midlateral stripe are presented.
[Praziquantel, levamisole and diflubenzuron in the control of Dolops carvalhoi (Crustacea: Branchiura) and Anacanthorus penilabiatus (Monogenea: Dactylogyridae) in Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes: Characidae)].
Schalch, Sergio Henrique Canello; de Moraes, Flávio Ruas; Soares, Vando Edésio
This assay evaluated the control efficacy of diflubenzuron, praziquantel and levamisole added to the diet of pacu (Piaractus mesoptamicus) infected with Anacanthorus penilabiatus and Dolops carvalhoi. 19 water tanks of 300 L capacity were utilized with 28 fish in each one. The treatments were made by mixing the active principles in the diet. The experiment was evaluated in four harvests done 1 day before and 3, 7 and 15 days after the treatment. The medicated feeding was applied for 7 days. The results of efficacy suggest that the diflubenzuron alone or associated with levamisole and praziquantel was efficient against the crustacean D. carvalhoi and the efficacy in the 3, 7 and 15 days evaluations ranged from 96.2 to 100%. Against the monogenean the drugs did not present efficacy. The results suggest the use of diflubenzuron for the control of D. carvalhoi in captive fishes in special conditions.
Review of species of the Astyanax bimaculatus "caudal peduncle spot"
subgroup sensu Garutti & Langeani (Characiformes, Characidae) from the rio La Plata and rio São Francisco drainages and coastal systems of southern Brazil and Uruguay.
Lucena, Carlos Alberto S De; Soares, Helena Gouvea
The species of the Astyanax bimaculatus 'caudal peduncle spot' subgroup of the drainages of the rios La Plata and São Francisco, as well as southeastern coastal systems of Brazil and Uruguay, are revised. Two nominal species are considered valid and are redescribed: Astyanax lacustris and A. abramis. Astyanax jacuhiensis, A. asuncionensis and A. altiparanae are recognized as new junior synonyms of A. lacustris. Bertoniolus paraguayensisis recognized as a new junior synonym of A. abramis. The names Astyanax orbignyanus, A. vittatus, and A. borealis are considered species inquirendae. Notes on A. maculisquamis, included in the 'caudal peduncle spot' subgroup from rio Guaporé (rio Madeira drainage), and Astyanax bahiensis from Bahia, mistakenly considered of the same subgroup, are presented.
Pacheco, Rosiley Berton; da Rosa, Renata; Giuliano-Caetano, Lucia; Júlio, Horácio Ferreira; Dias, Ana Lúcia
Two populations of Astyanax altiparanae (Garutti & Britski, 2000) of the Água dos Patos stream/SP and lake Igapó/PR were analyzed. All individuals showed 2n = 50, however, different karyotypic formulae were observed. The population of the Água dos Patos stream showed 8m +24sm+6st+12a (NF=88) and the population of lake Igapó, 8m+28sm+4st+10a (NF=90). Nucleolus organizing regions (AgNORs) were observed in the terminal position on the short and long arm of different chromosomes of both populations, showing a variation from 3 to 4 chromosomes. Fluorescent in situ hybridization (FISH) using 18S rDNA probes revealed only one pair of chromosomes with fluorescent signals in the terminal site on the short arm in the Igapó lake population, while the population of Água dos Patos stream showed 4 fluorescence terminal signals, characterizing a system of simple and multiple NORs, respectively. 5S rDNA fluorescent signals were detected in the interstitial position of a pair of chromosomes in the two studied populations. Some AgNOR sites revealed to be GC-rich when stained with Chromomycin A3 (CMA3), however, AT positive regions were not observed. The data obtained show that, despite the conservation of the diploid number and location of 5S DNAr, differences in both the distribution of 18S rDNA and karyotypic formula among the populations were found, thus corroborating the existing data on chromosome variability in Astyanax altiparanae that can be significant for cytotaxonomy in this group.
Basic cytogenetics and physical mapping of ribosomal genes in four Astyanax species (Characiformes, Characidae) collected in Middle Paraná River, Iguassu National Park: considerations on taxonomy and systematics of the genus
Paiz, Leonardo Marcel; Baumgärtner, Lucas; da Graça, Weferson Júnio; Margarido, Vladimir Pavan
Abstract Karyotypes and chromosomal characteristics of both minor and major rDNAs in four fish species known popularly as “lambaris”, namely Astyanax abramis (Jenyns, 1842), Astyanax asuncionensis Géry, 1972, Astyanax correntinus (Holmberg, 1891) and Astyanax sp. collected from downstream of the Iguassu Falls (Middle Paraná River basin), preservation area of the Iguassu National Park, were analyzed by conventional and molecular protocols. Astyanax abramis had diploid chromosome number 2n=50 (4m+30sm+8st+8a) and single AgNORs (pair 22), Astyanax asuncionensis had 2n=50 (8m+24sm+6st+12a) and single AgNORs (pair 20), Astyanax sp. had 2n=50 (4m+26sm+8st+12a) and single AgNORs (pair 25), and Astyanax correntinus had 2n=36 (12m+16sm+2st+6a) and multiple AgNORs (pairs 12, 15, 16, 17). FISH with 18S rDNA showed a single site for Astyanax abramis, Astyanax asuncionensis and Astyanax sp. and multiple for Astyanax correntinus (14 sites). FISH with 5S rDNA showed single 5S-bearing loci chromosome pair only for Astyanax asuncionensis and multiple for Astyanax abramis (four sites), Astyanax correntinus (five sites) and Astyanax sp. (four sites). Distinct distribution patterns of heterochromatin were observed for karyotypes of all species, with the exception of the first acrocentric chromosome pair characterized by centromeric, interstitial-proximal and telomeric blocks of heterochromatin on the long arm, which may represent homeology between karyotypes of Astyanax abramis and Astyanax asuncionensis. Our study showed species-specific characteristics which can serve in diagnosis and differentiation between Astyanax abramis and Astyanax asuncionensis, considered cryptic species, as well as strengthening the occurrence of a species of Astyanax not yet described taxonomically. In addition, the data obtained from first cytogenetic studies in Astyanax correntinus suggest a high similarity with Astyanax schubarti Britski, 1964, suggesting that these species may belong to the same morphological group and that can be phylogenetically related. PMID:25893074
Helminthological examination of specimens of the freshwater fishes Bryconamericus iheringi Boulenger, 1887 (Characidae) and Jenynsia multidentata (Jenyns, 1842) (Anablepidae), collected from Medina River, Province of Tucuman, Argentina, revealed the presence of 2 species of parasitic nematodes, Rhabdochona fabianae n. sp. and Rhabdochona acuminata (Molin, 1860) (Rhabdochonidae). Rhabdochona fabianae n. sp. was characterized by the presence of 16 anterior teeth in the prostom and filamented eggs in females. Rhabdochona acuminata was recorded for the first time in the north of Argentina.
A new species of the trichomycterid catfish genus Ituglanis is described from the Rio Curuá, Rio Xingu basin, Rio Amazonas drainage, Brazil. Ituglanis apteryx, new species, is promptly distinguished from congeners, except some specimens of I. parahybae (Eigenmann), by the absence of pelvic fins, girdle, and muscles. The new species differs from I. parahybae in the pattern of the cephalic laterosensory system; the absence of a posterior cranial fontanel; the presence of an epural; and the number of branchiostegal rays, ribs, and vertebrae. Ituglanis apteryx is one among the several trichomycterids lacking pelvic fins. Analysis reveals that pelvic fin loss independently evolved several times during the trichomycterid radiation.
Quist, M.C.; Hubert, W.A.; Isaak, D.J.
Fish and habitat were sampled from 110 reaches in the Salt River basin (Idaho and Wyoming) during 1996 and 1997 to assess patterns in fish assemblage structure across a Rocky Mountain watershed. We identified four distinct fish assemblages using cluster analysis: (1) allopatric cutthroat trout (Oncorhynchus clarki (Richardson, 1836)); (2) cutthroat trout - brook trout (Salvelinus fontinalis (Mitchell, 1814)) - Paiute sculpin (Cottus beldingi Eigenmann and Eigenmann, 1891); (3) cutthroat trout - brown trout (Salmo trutta L., 1758) - mottled sculpin (Cottus bairdi Girard, 1850); and (4) Cyprinidae-Catostomidae. The distribution of fish assemblages was explained by thermal characteristics, stream geomorphology, and local habitat features. Reaches with allopatric cutthroat trout and the cutthroat trout - brook trout - Paiute sculpin assemblage were located in high-elevation, high-gradient streams. The other two fish assemblages were generally located in low-elevation streams. Associations between habitat gradients, locations of reaches in the watershed, and occurrence of species were further examined using canonical correspondence analysis. The results suggest that stream geomorphology, thermal conditions, and local habitat characteristics influence fish assemblage structure across a Rocky Mountain watershed, and they provide information on the ecology of individual species that can guide conservation activities. ?? 2004 NRC Canada.
A morphological and molecular study of two species of Raphidascaroides Yamaguti, 1941 (Nematoda: Anisakidae), parasites of doradid catfish (Siluriformes) in South America, with a description of R. moraveci n. sp.
Pereira, Felipe B; Tavares, Luiz E R; Scholz, Tomáš; Luque, José L
Nematodes of the genus Raphidascaroides Yamaguti, 1941 parasitising doradid catfishes (Siluriformes: Doradidae) in Brazil were studied based on morphological and molecular evaluation of newly collected material. A new species, Raphidascaroides moraveci n. sp., is described from the intestine of Platydoras armatulus (Valenciennes) from River Miranda, River Paraguay basin, Pantanal, Mato Grosso do Sul. The new species differs from all of the congeners in having short spicules (163-217 μm in length) representing less than 1% of the total body length and in the posterior region of cloacal opening covered by small rudimentary spines. In addition, it differs from the other congeneric species in the number and arrangement of the caudal papillae and the structure of lips and tail. Raphidascaroides moraveci n. sp. is the third species described from freshwater fishes and the second one in the Neotropical Region. New morphological data on R. brasiliensis Moravec & Thatcher, 1997 from Megalodoras uranoscopus (Eigenmann & Eigenmann) and Platydoras costatus (Linnaeus) (both new host records) from River Xingu, River Amazon basin, Pará, are provided including scanning electron micrographs of taxonomically important structures. The differentiation of the new species is supported by molecular data (partial sequences of the small and large subunits of the rRNA gene).
Arredondo, Nathalia J; De Pertierra, Alicia A Gil; De Chambrier, Alain
This study describes the proteocephalidean tapeworm Pseudocrepidobothrium chanaorum sp. n. (Proteocephalidae: Proteocephalinae), which was found in the intestine of Pseudoplatystoma reticulatum (Eigenmann et Eigenmann) from the Colastiné River, a tributary of the Paraná River. The new species differs from the two other species of the genus, P. eirasi (Rego et de Chambrier, 1995) and P. ludovici Ruedi et de Chambrier, 2012, parasites of Phractocephalus hemioliopterus (Bloch et Schneider) from the Amazon River in Brazil, in having fewer proglottides (4-8 without ventral appendages vs 7-12 with ventral appendages and 20-36 without ventral appendages, respectively), a smaller scolex (350-450 μm wide vs 495-990 μm and 515-1020 μm wide, respectively), in the total number of testes (21-25 vs 21-51 and 37-79, respectively), a cirrus-sac usually directed anteriorly if the vagina is posterior to the cirrus-sac vs transversely situated in the known species. The study of the tegumental surface of Pseudocrepidobothrium spp. revealed the presence of four types of microtriches: papilliform, acicular and capilliform filitriches, and gladiate spinitriches. The three species have a similar microthrix pattern, with minor differences on the immature proglottis surface. Pseudocrepidobothrium chanaorum sp. n. is the ninth proteocephalid reported from P. reticulatum.
New species of Ameloblastella Kritsky, Mendoza-Franco & Scholz, 2000 and Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986 (Monogenea: Dactylogyridae) infecting the gills of catfishes (Siluriformes) from the Peruvian Amazonia.
Mendoza-Franco, Edgar F; Mendoza-Palmero, Carlos A; Scholz, Tomáš
During a research on gill ectoparasites of siluriform fishes from the Peruvian Amazonia, the following monogeneans were found: Ameloblastella edentensis n. sp. from Hypophthalmus edentatus Spix & Agassiz; Ameloblastella peruensis n. sp. from Hypophthalmus sp.; Ameloblastella formatrium n. sp. from Pimelodidae gen. sp. (type-host) and Duopalatinus cf. peruanus Eigenmann & Allen; Ameloblastella unapioides n. sp. from Sorubim lima (Bloch & Schneider) (type-host) and Pimelodus sp; Cosmetocleithrum tortum n. sp. from Nemadoras hemipeltis (Eigenmann); and Cosmetocleithrum bifurcum n. sp. from Hassar orestis (Steindachner) (both Doradidae). All new species described herein are mainly differentiated from their congeners based on the morphology of the copulatory complex. The pimelodids H. edentatus and S. lima, and the doradids N. hemipeltis and H. orestis represent new hosts species for species of Ameloblastella Kritsky, Mendoza-Franco & Scholz, 2000 and Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986, respectively. The morphological diagnosis of the present species of Ameloblastella and Cosmetocleithrum also supported by a previous molecular analysis of these species is briefly discusssed herein.
Moravec, F; Huffman, D G
A new nematode species, Rhabdochona longleyi sp. n. is described from the intestine of two species of blind catfishes, Trogloglanis pattersoni Eigenmann (type host) and Satan eurystomus Hubbs et Bailey (both fam. Ictaluridae, Siluriformes) from the subterranean waters (artesian wells penetrating San Antonio pool of Edwards Aquifer) of Texas, USA. It is characterized largely by the presence of only six anterior teeth in the prostom, simple deirids, by the shape and length of spicules (0.42 to 0.50 mm and 0.093-0.102 mm), shape of the tail tip (rounded), and by filamented eggs. R. longleyi probably adapted to the environment of the aquifer by utilizing available troglobitic crustaceans instead of aquatic insects as an intermediate host.
Webb, D Harry; Marrero, Cynthia; Ellis, Helen; Merriwether, Lea; Dove, Alistair D M
A reagent-free spectrophotometric assay was developed to measure the concentration of metronidazole (a 5-nitroimidazole) in both freshwater and seawater matrices. This assay is simple, repeatable, sensitive, and precise and is ideal for use when a rapid, selective test to determine metronidazole concentration in aqueous matrices is necessary. The assay was practically tested on a South American fishes display during treatment with metronidazole for an outbreak of the flagellated parasite Spironucleus in a mixed cichlid (family Cichlidae) and tetra (family Characidae) community. The assay clearly illustrated the course of treatment for the system during a real clinical application. The assay is not without limitations, as interferences can occur from other drugs in the matrix with similar absorbance spectra. Nonetheless, this type of assay illustrates the potential for use of native absorbance assays in aqueous matrices for this and other therapeutic compounds.
Fujimoto, Rodrigo Yudi; Almeida, Edilene Santos; Diniz, Daniel Guerreiro; Eiras, Jorge Costa; Martins, Mauricio Laterça
The objective of this work was to report the first seasonal occurrence of the acanthocephalan Quadrigyrus nickoli Schmidt & Hugghins, 1973 (Quadrigyridae), in the "Mato Grosso" Hyphessobrycon eques (Characidae) (Steindachner, 1882), collected from the Chumucuí River, state of Pará, Brazil. The fish were collected between July 2006 (rainy season) and June 2007 (dry season) and were examined for parasites using pattern techniques. A total of 75 parasites were found in the stomach and intestine. Among 83 fish examined (50 in the dry season and 33 in the rainy season), 22 were parasitized by cystacanths of Q. nickoli. The importance of H. eques as a paratenic host for Q. nickoli is discussed. This is the first study on the biology of and infection by Q. nickoli occurring in the eastern Amazon region.
Carlson, Elof Axel
Fruit flies were used by several laboratories between 1901 and 1910 for studies of experimental evolution at Harvard, Indiana University, and Cold Spring Harbor before Thomas Hunt Morgan found his white-eyed mutation that we associate with the beginnings of the fly lab at Columbia University. The major players prior to Morgan were William Castle and his students at Harvard University, Frank Lutz at Cold Spring Harbor, and Fernandus Payne whose ideas for working with fruit flies were shaped by his studies of blind cave fauna at Indiana University. Payne's interests were stimulated by the work of Carl Eigenmann, an authority on blind cave fauna, and William Moenkhaus, who introduced Payne to fruit flies at Indiana University before Payne moved to Columbia to pursue graduate work with Morgan and Edmund Wilson. The motivations of the laboratories differed in the theories used for their work. Castle spread the word about the utility of fruit flies for research, but Payne gave Morgan his first fruit flies for research leading to the discovery of the white-eye mutation.
Fernandes, Carlos Alexandre; Alves, Diandra Soares; Guterres, Zaira da Rosa; Martins-Santos, Isabel Cristina
Abstract Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters. In this study, were cytogenetically examined two species of Loricariidae (Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 and Farlowella amazonum (Günther, 1864) belonging to Hypostominae and Loricariinae subfamilies respectively) from Iguatemi River. Our study provide the first description regarding C-band and fluorochromic analysis in Farlowella amazonum. In Farlowella amazonum, diploid number was 58 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric regions of some chromosomes and large subtelomeric blocks were evidenced on the long arm of the pair 27, being this region CMA3+/DAPI-. The Pterygoplichthys anisitsi showed diploid number equal 52 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric and telomeric regions of some chromosomes and conspicuous large telomeric blocks on the long arm of the pair 10, being this region CMA3+/DAPI-. The results show that karyotype formula is nonconservative in Pterygoplichthys anisitsi and Farlowella amazonum. PMID:25893075
Lisitsyna, Olga; Scholz, Tomáš; Kuchta, Roman
Sharpilosentis peruviensis n. g., n. sp. is described from the catfishes Duopalatinus cf. peruanus Eigenmann & Allen (type-host) and Oxydoras niger (Valenciennes) in the River Amazon basin, Peru. The new species belongs to the subfamily Diplosentinae Tubangui & Masilungan, 1937 of the family Diplosentidae Tubangui & Masilungan, 1937 because of its possession of an unarmed trunk, a cylindrical proboscis, proboscis hooks arranged in longitudinal rows and two tubular cement glands of the same length in males. Sharpilosentis n. g. differs from the other genera of the Diplosentidae in the morphology of the reproductive system: males have a large muscular penis covered with small tubercles and the vulva of females is devoid of muscular sphincters and the cephalic ganglion is located between the second and third part of the proboscis receptacle. In addition, proboscis hooks are of three types: large hooks with simple roots in the anterior part of the proboscis, transitional 6th hook in one from two adjacent rows with bifurcated root in the distal part and small hooks without roots in the posterior part of the proboscis. A partial sequence for the mitochondrial cox1 gene is provided for this new taxon. The taxonomic composition of the family Diplosentidae is discussed.
Souza, Kleisson S; Bastazini, Vinicius A G; Colares, Elton P
The present study was based on the analysis of spraints (n = 294) collected between December 2005 and November 2007. The importance of each type of prey was determined by absolute and relative frequency. Niche breadth was also estimated. The results were reported as mean (± SD) of relative frequencies. Fish were the main prey found in spraints (57.8 ± 7.0%). Fish from Callichthyidae family were the main prey, followed by Cichlidae, the species Hoplias malabaricus and the family Characidae. The frequencies of other fish and taxa were lower than 13.9% (absolute frequency) and 5.6% (relative frequency). Despite significant seasonal variations, (P = 0.001), niche breadth values were low in all seasons (0.39 ± 0.11). Therefore, Lontra longicaudis presented a narrow niche breadth as a result of consistent fish predation. Based on these data, fish with rapid movement presenting territorial behavior and benthic fish with slow movements are the most consumed. Seasonal fluctuations are caused by the increase of secondary prey in the diet during some seasons.
Assumpção, Cindy M; Quintela, Fernando M; Corrêa, Fabiano; Loebmann, Daniel
The Quaternary in the state of Rio Grande do Sul (RS), southern Brazil, is geologically represented by the coastal plain and was originated by successive events of Pleistocene-Holocene marine transgressions and the occurrence of alluvial deposits. This paper aimed to characterize the fish assemblage occurring in a swampy Quaternary area adjacent to Lagoa Pequena, a lacustrine system connected to the west margin of the Laguna dos Patos estuary. A checklist is also provided of the ichthyofauna so far recorded in limnic systems of Quaternary deposits in the state of Rio Grande do Sul. A total of 42 species was recorded, distributed in nine orders, 18 families and 31 genera. Characidae and Cichlidae were the most representative families, comprising 15 and 4 species respectively. A bibliographic revision associated to our sample data revealed the occurrence of 156 species in limnic systems inserted in RS Quaternary deposits (114 limnic, 15 marine/estuarine/limnic, ten marine/estuarine, nine estuarine/limnic and eight marine). Characiformes and Siluriformes are the most diverse orders, corroborating the Neotropical pattern. Seven species can be considered endemic to RS Quaternary deposits.
Valdez-Moreno, M; Ivanova, N V; Elías-Gutiérrez, M; Contreras-Balderas, S; Hebert, P D N
The freshwater fish fauna of Mexico and Guatemala is exceptionally diverse with >600 species, many endemic. In this study, patterns of sequence divergence were analysed in representatives of this fauna using cytochrome c oxidase subunit 1 (COI) DNA barcodes for 61 species in 36 genera. The average divergence among conspecific individuals was 0.45%, while congeneric taxa showed 5.1% divergence. Three species of Poblana, each occupying a different crater lake in the arid regions of Central Mexico, have had a controversial taxonomic history but are usually regarded as endemics to a single lake. They possess identical COI barcodes, suggesting a very recent history of isolation. Representatives of the Cichlidae, a complex and poorly understood family, were well discriminated by barcodes. Many species of Characidae seem to be young, with low divergence values (<2%), but nevertheless, clear barcode clusters were apparent in the Bramocharax-Astyanax complex. The symbranchid, Opisthernon aenigmaticum, has been regarded as a single species ranging from Guatemala to Mexico, but it includes two deeply divergent barcode lineages, one a possible new endemic species. Aside from these special cases, the results confirm that DNA barcodes will be highly effective in discriminating freshwater fishes from Central America and that a comprehensive analysis will provide new important insights for understanding diversity of this fauna.
Assumpção, Cindy M.; Quintela, Fernando M.; Corrêa, Fabiano; Loebmann, Daniel
Abstract The Quaternary in the state of Rio Grande do Sul (RS), southern Brazil, is geologically represented by the coastal plain and was originated by successive events of Pleistocene-Holocene marine transgressions and the occurrence of alluvial deposits. This paper aimed to characterize the fish assemblage occurring in a swampy Quaternary area adjacent to Lagoa Pequena, a lacustrine system connected to the west margin of the Laguna dos Patos estuary. A checklist is also provided of the ichthyofauna so far recorded in limnic systems of Quaternary deposits in the state of Rio Grande do Sul. A total of 42 species was recorded, distributed in nine orders, 18 families and 31 genera. Characidae and Cichlidae were the most representative families, comprising 15 and 4 species respectively. A bibliographic revision associated to our sample data revealed the occurrence of 156 species in limnic systems inserted in RS Quaternary deposits (114 limnic, 15 marine/estuarine/limnic, ten marine/estuarine, nine estuarine/limnic and eight marine). Characiformes and Siluriformes are the most diverse orders, corroborating the Neotropical pattern. Seven species can be considered endemic to RS Quaternary deposits. PMID:28174498
Andrade, P M; Braga, F M S
We compare the classic model of feeding of tropical fish by means of six bimonthly samplings using gillnets of varying mesh sizes that were inspected every twelve hours throughout a forty-eight hour period. The stomachs of the fish caught were classified in three categories according to quantity of food found. The amount of fat in the visceral cavity with respect to the energetic reserve deposition was also studied. The relative frequencies of the different categories of stomach repletion and fat deposition were examined for patterns of feeding seasonality. The stomachs considered full were examined to record diet composition. To assess the relative importance of the different food resources, we applied Feeding Importance Degree (FID), which is a useful index when difficulties exist in determining a common basis for volume, number, or weight of a given food item in different species, a common problem when dealing with fish species having different feeding habits. The fish species whose stomach contents were analyzed using the FID index were Serrasalmus spilopleura (Characidae), L. prolixa (Loricaridae), Schizodon nasutus (Anostomidae), and Pimelodus maculatus (Pimelodidae). Our findings indicate some contrasting elements, in dietary composition in relation to the classic model for tropical rivers. These factors include the importance of aquatic macrophytes, the lack of piscivorous species, and a lesser presence of allochthonous vegetation in the diet of the species studied.
Escobar-Camacho, Daniel; Barriga, Ramiro; Ron, Santiago R.
Background Management and conservation of biodiversity requires adequate species inventories. The Yasuní National Park is one of the most diverse regions on Earth and recent studies of terrestrial vertebrates, based on genetic evidence, have shown high levels of cryptic and undescribed diversity. Few genetic studies have been carried out in freshwater fishes from western Amazonia. Thus, in contrast with terrestrial vertebrates, their content of cryptic diversity remains unknown. In this study, we carried out genetic and morphological analyses on characin fishes at Yasuní National Park, in eastern Ecuador. Our goal was to identify cryptic diversity among one of the most speciose fish families in the Amazon region. This is the first time that genetic evidence has been used to assess the species content of the Napo Basin, one of the richest regions in vertebrate diversity. Results Phylogenetic analyses of partial mitochondrial 16S ribosomal RNA gene (∼600 pb) DNA sequences from 232 specimens of the family Characidae and its closest groups revealed eight candidate new species among 33 species sampled, representing a 24% increase in species number. Analyses of external morphology allowed us to confirm the species status of six of the candidate species. Conclusions Our results show high levels of cryptic diversity in Amazonian characins. If this group is representative of other Amazonian fish, our results would imply that the species richness of the Amazonian ichthyofauna is highly underestimated. Molecular methods are a necessary tool to obtain more realistic inventories of Neotropical freshwater fishes. PMID:26275041
Baras, E; Lucas, M C
The growth of sibling dorada Brycon moorei (Characidae) housed individually in small enclosures (0·25 l; 27·0° C, range ±0·5° C; 12L:12D) from the egg stage was examined at regular intervals until 36 days after hatching (dah) and compared with their behaviour. From 1 to 8 dah, when cannibalism is intense among B. moorei raised in groups, there was no significant increase of size heterogeneity among isolated fish (c.v. of total length of 3·1 and 3·6%, at 1 and 8 dah, respectively) and no primacy of early size differences either. These results suggest that cannibals of B. moorei raised in groups are not natural-born killers with greater growth capacities than others. Size heterogeneity among isolated fish increased significantly first when B. moorei were weaned on formulated feed (8-15 dah), then again from 24 to 36 dah when the average growth rate was half as fast as before (c. 0·5 v. 1·0 mm day(-1) ), despite fish consistently feeding. During both periods, there was a significant, positive relationship between individual growth and aggression or boldness. These results suggest that (1) boldness can favour the transition to a new food type and (2) fish exhibited a variable responsiveness to spatial restriction in small enclosures, which may have been alleviated in some individuals by establishment of territorial behaviour, as suggested by their enhanced aggression.
Oliveira, Carlos Alexandre Miranda; de Melo, Filipe Augusto Gonçalves; Bertaco, Vinicius de Araújo; de Astarloa, Juan M. Díaz; Rosso, Juan J.; Foresti, Fausto; Oliveira, Claudio
DNA barcoding has been used extensively to solve taxonomic questions and identify new species. Neotropical fishes are found in a wide variety of shapes and sizes, with a large number of species yet to be described, many of which are very difficult to identify. Characidae is the most species-rich family of the Characiformes, and many of its genera are affected by taxonomic uncertainties, including the widely-distributed, species-rich genus Astyanax. In this study, we present an extensive analysis of Astyanax covering almost its entire area of occurrence, based on DNA barcoding. The use of different approaches (ABGD, GMYC and BIN) to the clustering of the sequences revealed ample consistency in the results obtained by the initial cutoff value of 2% divergence for putative species in the Neighbor-Joining analysis using the Kimura-2-parameter model. The results indicate the existence of five Astyanax lineages. Some groups, such as that composed by the trans-Andean forms, are mostly composed of well-defined species, and in others a number of nominal species are clustered together, hampering the delimitation of species, which in many cases proved impossible. The results confirm the extreme complexity of the systematics of the genus Astyanax and show that DNA barcoding can be an useful tool to address these complexes questions. PMID:27992537
Granado-Lorencio, Carlos; Serna, Andrés Hernández; Carvajal, Juan David; Jiménez-Segura, Luz Fernanda; Gulfo, Alejandra; Alvarez, Frank
We investigated if fish assemblages in neotropical floodplain lakes (cienagas) exhibit nestedness, and thus offer support to the managers of natural resources of the area for their decision making. The location was floodplain lakes of the middle section of the Magdalena river, Colombia. We applied the nested subset analysis for the series of 30 cienagas (27 connected to the main river and three isolated). All fish were identified taxonomically in the field and the matrix for presence-absence in all the lakes was used for the study of the pattern of nestedness. The most diverse order was Characiformes (20 species), followed by Siluriformes (19 species). Characidae and Loricaridae were the richest families. The species found in all the lakes studied were migratory species (17), and sedentary species (33). Two species (Caquetaia kraussii and Cyphocharax magdalenae) were widespread across the cienagas archipelago (100% of incidence). Nestedness analysis showed that the distribution of species over the spatial gradient studied (840 km) is significantly nested. The cienagas deemed the most hospitable were Simiti, El Llanito, and Canaletal. Roughly, 13 out of the 50 species caught show markedly idiosyncratic distributions. The resulting dataset showed a strong pattern of nestedness in the distribution of Magdalenese fishes, and differed significantly from random species assemblages. Out of all the measurements taken in the cienagas, only the size (area) and local richness are significantly related to the range of order of nested subset patterns (r=-0.59 and -0.90, respectively, at p < 0.01). Differential species extinction is suggested as the cause of a nested species assemblage, when the reorganized matrix of species occurring in habitat islands is correlated with the island area. Our results are consistent with this hypothesis.
Anderson, Jill T; Saldaña Rojas, Joe; Flecker, Alexander S
Seed dispersal is a critical stage in the life history of plants. It determines the initial pattern of juvenile distribution, and can influence community dynamics and the evolutionary trajectories of individual species. Vertebrate frugivores are the primary vector of seed dispersal in tropical forests; however, most studies of seed dispersal focus on birds, bats and monkeys. Nevertheless, South America harbors at least 200 species of frugivorous fishes, which move into temporarily flooded habitats during lengthy flood seasons and consume fruits that fall into the water; and yet, we know remarkably little about the quality of seed dispersal they effect. We investigated the seed dispersal activities of two species of large-bodied, commercially important fishes (Colossoma macropomum and Piaractus brachypomus, Characidae) over 3 years in Pacaya-Samiria National Reserve (Peru). We assessed the diet of these fishes during the flood season, conducted germination trials with seeds collected from digestive tracts, and quantified fruit availability. In the laboratory, we fed fruits to captive Colossoma, quantified the proportion of seeds defecated by adult and juvenile fish, and used these seeds in additional germination experiments. Our results indicate that Colossoma and Piaractus disperse large quantities of seeds from up to 35% of the trees and lianas that fruit during the flood season. Additionally, these seeds can germinate after floodwaters recede. Overexploitation has reduced the abundance of our focal fish species, as well as changed the age structure of populations. Moreover, older fish are more effective seed dispersers than smaller, juvenile fish. Overfishing, therefore, likely selects for the poorest seed dispersers, thus disrupting an ancient interaction between seeds and their dispersal agents.
Quarcoopome, Theodore; Amevenku, Francis; Ofori-Danson, Patrick
The Kpong Headpond was the second created on the Volta River after Akosombo Dam, primarily as a source of hydroelectric power generation and potable water supply, and additionally, it has supported some fish production in Ghana since impoundment. The changes in fish community of the Kpong Headpond were studied to provide baseline information for strategies formulation to support the socio-economic development of the reservoir. The study identified changes in the fish community of the reservoir by comparing occurrence, composition, relative abundance and relative importance estimates of fish species, families and trophic groups, from available previous studies in the reservoir. From the collated information all fishes identified in the reservoir were categorised based on occurrence and importance as disappeared, appeared, permanent, declined or important, to show current status. The results indicated that the fish community has experienced a shift in the composition and relative abundance of important species, families and trophic groups in terms of number and weight, while remaining ecologically balanced. Representatives of the families Osteoglossidae, Centropomidae and Characidae have declined while representatives of the families Claroteidae, Cyprinidae and Cichlidae have increased. The aufwuch-detritus and herbivores declined while semi-pelagic omnivores increased resulting in a shift in dominance to benthic and semi pelagic omnivores. The appearance of five species and the disappearance of 25 others indicated a dynamic restructuring of the fish community in the reservoir, as expected. Enforcement of fishing regulations including the use of appropriate gear and fishing methods, fishery access control, promotion of culture-based fisheries and improvement in fisher education are recommended topics for sustainable fisheries in the reservoir.
Granado-Lorencio, Carlos; Serna, Andrés Hernández; Carvajal, Juan David; Jiménez-Segura, Luz Fernanda; Gulfo, Alejandra; Alvarez, Frank
We investigated if fish assemblages in neotropical floodplain lakes (cienagas) exhibit nestedness, and thus offer support to the managers of natural resources of the area for their decision making. The location was floodplain lakes of the middle section of the Magdalena river, Colombia. We applied the nested subset analysis for the series of 30 cienagas (27 connected to the main river and three isolated). All fish were identified taxonomically in the field and the matrix for presence–absence in all the lakes was used for the study of the pattern of nestedness. The most diverse order was Characiformes (20 species), followed by Siluriformes (19 species). Characidae and Loricaridae were the richest families. The species found in all the lakes studied were migratory species (17), and sedentary species (33). Two species (Caquetaia kraussii and Cyphocharax magdalenae) were widespread across the cienagas archipelago (100% of incidence). Nestedness analysis showed that the distribution of species over the spatial gradient studied (840 km) is significantly nested. The cienagas deemed the most hospitable were Simiti, El Llanito, and Canaletal. Roughly, 13 out of the 50 species caught show markedly idiosyncratic distributions. The resulting dataset showed a strong pattern of nestedness in the distribution of Magdalenese fishes, and differed significantly from random species assemblages. Out of all the measurements taken in the cienagas, only the size (area) and local richness are significantly related to the range of order of nested subset patterns (r=–0.59 and –0.90, respectively, at p < 0.01). Differential species extinction is suggested as the cause of a nested species assemblage, when the reorganized matrix of species occurring in habitat islands is correlated with the island area. Our results are consistent with this hypothesis. PMID:22833801
Mena, F; Azzopardi, M; Pfennig, S; Ruepert, C; Tedengren, M; Castillo, L E; Gunnarsson, J S
In Costa Rica, thousands of tones of agricultural pesticides have been used for decades and their use is continuously increasing due to intensive and expanding production of coffee, pineapple, rice, ornamental plants and bananas. The objective of this study was to evaluate whether choline esterase (ChE) activity could be used as a biomarker of exposure to pesticides in the Costa Rican native fish Astyanax aeneus (characidae). Three methods used in order to evaluate the ChE biomarker were as follows: Laboratory studies where A. aeneus was exposed to organophosphate pesticide (ethoprophos); In situ 48 hr exposure assessment using caging experiments with fish exposed upstream and downstream of banana plantations and ChE activity estimation of in fish captured directly at sites with different degrees of pesticide exposure. Results from the laboratory studies showed that ChE activity in both brain and muscle tissue was significantly lower in fish exposed to ethoprophos than in controls. Fish from the caging experiments showed no difference in ChE activity neither in brain nor in muscle tissue between the four tested sites and was attributed to the short duration of the exposure. Asignificant difference in ChE activity was determined in muscle of fish captured from Laguna Madre de Dios compared to fish from Canal Batán. Although our laboratory results revealed that ChE activity in A. aeneus was highly responsive to ethoprophos, results from field experiments were less conclusive and showed that the captured fish showed large variability in ChE activity and that more research is needed before ChE activity can be used as reliable biomarker of pesticide exposure.
Zambrano, L.; Vazquez-Dominguez, E.; Garcia-Bedoya, D.; Loftus, W.F.; Trexler, J.C.
We evaluated the relationship between limnetic characteristics and fish community structure (based on species richness, abundance and individual size) in contrasting but interconnected inland aquatic habitats of freshwater karstic wetlands in the Yucatan peninsula, Mexico. In the western hemisphere, freshwater karstic wetlands are found in south-eastern Mexico, northern Belize, western Cuba, Andros Island, Bahamas and the Everglades of southern Florida. Only in the Everglades have fish communities been well described. Karstic wetlands are typically oligotrophic because calcium carbonate binds phosphorus, making it relatively unavailable for plants. Fourteen permanent and seasonally flooded water bodies were sampled in both wet and dry seasons in Sian Ka'an Biosphere Reserve, in the Mexican state of Quintana Roo. Water systems were divided by morphology in four groups: cenotes with vegetation (CWV), cenotes without vegetation (CNV), wetlands (WTL), and temporal cenotes (TPC). Discriminant analysis based on physical characteristics such as turbidity, temperature, depth and oxygen confirmed that these habitats differed in characteristics known to influence fish communities. A sample-based rarefaction test showed that species richness was significantly different between water systems groups, showing that WTL and CWV had higher richness values than CNV and TPC. The most abundant fish families, Poeciliidae, Cichlidae and Characidae, differed significantly in average size among habitats and seasons. Seasonal and inter-annual variation, reflecting temporal variation in rainfall, strongly influenced the environmental differences between shallow and deep habitats, which could be linked to fish size and life cycles. Five new records of species were found for the reserve, and one new record for Quintana Roo state. ?? 2006 by Verlag Dr. Friedrich Pfeil.
Sharpe, D M T; De León, L F; González, R; Torchin, M E
Predation is considered to be an important factor structuring natural communities. However, it is often difficult to determine how it may influence long-term, broad-scale, diversity patterns, particularly in diverse tropical systems. Biological introductions can provide powerful insight to test the sustained consequences of predation in natural communities, if pre-introduction data are available. Half a century ago, Zaret and Paine demonstrated strong and immediate community-level effects following the introduction of a novel apex predator (peacock bass, Cichla monoculus) into Lake Gatun, Panama. To test for long-term changes associated with this predator introduction, we followed up on their classic study by replicating historical sampling methods and examining changes in the littoral fish community at two sites in Lake Gatun 45 years post-introduction. To broaden our inference, we complemented this temporal comparison with a spatial analysis, wherein we compared the fish communities from two lakes with and one lake without peacock bass. Comparisons with historical data revealed that the peacock bass remains the most abundant predator in Lake Gatun. Furthermore, the collapse of the littoral prey community observed immediately following the invasion has been sustained over the past 45 years. The mean abundance of native littoral fish is now 96% lower than it was prior to the introduction. Diversity (rarefied species richness) declined by 64% post-introduction, and some native species appear to have been locally extirpated. We observed a similar pattern across invaded and uninvaded lakes: the mean abundance of native fishes was 5-40 times lower in lakes with (Gatun, Alajuela) relative to the lake without peacock bass (Bayano). In particular, small-bodied native fishes (Characidae, Peociliidae), which are common prey of the peacock bass, were more than two orders of magnitude (307 times) less abundant in Gatun and one order of magnitude (28 times) less abundant in