BackgroundThe phylogenetic position of pycnogonids is a long-standing and controversial issue in arthropod phylogeny. This controversy has recently been rekindled by differences in the conclusions based on neuroanatomical data concerning the chelifore and the patterns of Hox expression. The mitochondrial genome of a sea spider, Nymphon gracile (Pycnogonida, Nymphonidae), was ...

In this report, we analyze the phylogeny of Pycnogonida using the three nuclear and three mitochondrial markers currently sequenced for studying inter- and intrafamilial relationships within Arthropoda: 18S and 28S rRNA genes, Histone H3, cytochrome c oxidase subunit 1 (CO1), 12S and 16S rRNA genes. We identify several problems in previous studies, due to the use of ...

... E., D. Bückmann, and K. H. Tomaschko. 1997. Life cycle and population dynamics of Pycnogonum litorale (Pycnogonida) in a natural habitat. Marine Biology 129:601�606. CrossRef, CSA enlarge figure Figure ....

Pycnogonida from the SEPBOP Expeditions and additional unreported specimens from other collections are described. They contain 30 described species, with an additional 10 newly described and 4 undescribed for lack of suitable specimens. The newly describe...

One hundred of the 155 known Japanese species of Pycnogonida (plus 4 unnamed species) were collected for the report and these are described and their distribution listed. These include 20 new species fully described and figured with five additional figure...

Description: SCARMarBIN Data System "Admiralty Bay Benthos Diversity Data Base ( ABBED). Pycnogonida. ... CAML >CENSUS OF ANTARCTIC MARINE LIFE [Information] ...

Language: English ...

Dataset Title: Check-list of the antarctic and sub-antarctic sea spiders ( Pycnogonida). Parent DIF. This data set description is a member of a collection. ...

Dataset Title: Check-list of the antarctic and sub-antarctic sea spiders ( Pycnogonida). Parent DIF. This data set description is a member of a collection. ...

Rotifera � Acantocephala � Nemertea � Mollusca � Annelida � Echiura � Sipuncula � Tardigrada � Pycnogonida � Xyphosura � Crustacea � Gastrotricha ...

Admiralty Bay Benthos Diversity Data Base (ABBED). Pycnogonida. Entry ID: scarmarbin_1649. [ View Full Record ]. [ Update this Record ] ...

[Pentapycnon] Stiboy-Risch, 1994 (junior syn. of Pentapycnon bouvieri Pushkin, 1993). 1 adult PT. ANTARCTICA of the Russian Academy of Science 1(4): 43-50. [in Russian] Pushkin AF (1993) The Pycnogonida fauna of the South

,867 meters in the northwest portion of the Gulf southeast of Atcha- falaya Bay. The distribution by Rothwell from several locations in the northwest part of the Gulf off Galveston and west of Atchafalaya Bay of the northwest portion of the Gulf from Mata- gorda Bay to near Atchafalaya Bay. It was originally reported

BackgroundMitochondrial genomes form units of genetic information replicating indepentently from nuclear genomes. Sequence data (most often from protein-coding genes) and other features (gene order, RNA secondary structure) of mitochondrial genomes are often used in phylogenetic studies of metazoan animals from population to phylum level. Pycnogonids are primarily marine arthropods, often ...

The phylogenetic position of the enigmatic Pycnogonida (sea spiders) is still controversial. This is in part due to a lack of detailed data about the morphology and ontogenesis of this, in many aspects, aberrant group. In particular, studies on the embryonic development of pycnogonids are rare and in part contradictory. Here, we present the first embryological study of a ...

We present the almost complete (16,007 bp) mitochondrial genome of a Colossendeis megalonyx specimen from the Southern Ocean and discuss gene order and tRNA structure in a comparative phylogenetic context. Our data suggest a basal position of the colossendeid lineage corroborating earlier phylogenetic studies but disagreeing with results of a recently published study that supported a highly ...

Invasion of the land by arachnids required adaptations of numerous organs, such as gills evolving into lungs, as well as mechanisms facilitating sperm transfer in a terrestrial environment. Many modern arachnids use spermatophores for this purpose, i.e. sperm transmitters detached from the body. Exceptionally preserved Silurian (423�Ma) fossils of Eurypterus tetragonophthalmus Fischer, 1839 ...

Invasion of the land by arachnids required adaptations of numerous organs, such as gills evolving into lungs, as well as mechanisms facilitating sperm transfer in a terrestrial environment. Many modern arachnids use spermatophores for this purpose, i.e. sperm transmitters detached from the body. Exceptionally preserved Silurian (423 Ma) fossils of Eurypterus tetragonophthalmus Fischer, 1839 ...

Former light microscopic studies on the lateral sense organs of sea spiders yielded divergent results. Consequently, different authors ascribed different functions to these organs. The present ultrastructural study shows that each lateral sense organ of A. pygmaeus consists of approximately 15 sensory cells of two different types, approximately 20 sheath cells with numerous long microvilli, and an ...

In this study, mitochondrial sequences were used to investigate the relationships among the major lineages of Arthropoda. The data matrix used for the analyses includes 84 taxa and 3918 nucleotides representing six mitochondrial protein-coding genes (atp6 and 8, cox1-3, and nad2). The analyses of nucleotide composition show that a reverse strand-bias, i.e., characterized by an excess of T relative ...

The pycnogonids (or sea spiders) are an enigmatic group of arthropods, classified in recent phylogenies as a sister-group of either euchelicerates (horseshoe crabs and arachnids), or all other extant arthropods. Because of their bizarre morpho-anatomy, homologies with other arthropod taxa have been difficult to assess. We review the main morphology-based hypotheses of correspondence between ...

Chelicerata probably appeared during the Cambrian period. Their precise origins remain unclear, but may lie among the so-called great appendage arthropods. By the late Cambrian there is evidence for both Pycnogonida and Euchelicerata. Relationships between the principal euchelicerate lineages are unresolved, but Xiphosura, Eurypterida and Chasmataspidida (the last two ...

Robust resolution of controversial higher-level groupings within Arthropoda requires additional sources of characters. Toward this end, elongation factor-2 sequences (1899 nucleotides) were generated from 17 arthropod taxa (5 chelicerates, 6 crustaceans, 3 hexapods, 3 myriapods) plus an onychophoran and a tardigrade as outgroups. Likelihood and parsimony analyses of nucleotide and amino acid data ...

In recent years, phylogenetic tree reconstructions that rely on multiple gene alignments that had been deduced from expressed sequence tags (ESTs) have become a popular method in molecular systematics. Here, we present a 454 pyrosequencing approach to infer the transcriptome of the Emperor scorpion Pandinus imperator. We obtained 428,844 high-quality reads (mean length=223+/-50 b) from total cDNA, ...