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Andrey V. Adrianov - One of the best experts on this subject based on the ideXlab platform.
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Deep-sea Sipunculans (Sipuncula) of the northwestern Pacific
Russian Journal of Marine Biology, 2017Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:Based on the available literature data, museum collections, and our own material, a review is presented on Sipunculan species of the northwestern Pacific that occur at depths greater than 500 m. Brief morphological descriptions showing the main characters used in taxonomy and a key for the identification of deep-sea Sipunculans of the northwestern Pacific to species level are proposed. The key includes 22 valid species representing 7 genera and 5 families of Sipuncula.
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the microscopic anatomy and ultrastructure of the contractile vessel in the Sipunculan themiste hexadactyla sato 1930 Sipuncula sipunculidea
Russian Journal of Marine Biology, 2014Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:The microscopic anatomy and ultrastructure of the contractile vessel of the Sipunculan Themiste hexadactyla (Sato, 1930) from Vostok Bay (the Sea of Japan) were studied by histological and electron microscope methods. The ultrastructural features of the internal (endothelium) and external (coelothelium) lining of the contractile vessel are described and illustrated. Numerous macromolecular filters, the so-called “double diaphragms,” were found in the external coelothelium facing the cavity of the trunk coelom. This suggests a possible filtration from the tentacular coelom into the trunk coelom though the contractile vessel wall. The microscopic peculiarities of the main tube of the contractile vessel and its numerous lateral branches twining around several internal organs are described in detail. The contractile vessel is polyfunctional: it can act as the main reservoir for the cavity fluid during the withdrawal of the tentacular crown and performs the functions of the distribution system in Sipunculans.
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the microscopic anatomy and ultrastructure of the nephridium of the Sipunculan themiste hexadactyla sato 1930 Sipuncula sipunculidea
Russian Journal of Marine Biology, 2014Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:The microscopic anatomy and ultrastructure of the nephridia of the Sipunculan Themiste hexadactyla (Sato, 1930) from the Sea of Japan were studied by the histological and electron microscopic methods. The fine structures of the ciliary funnel, muscular “tongue,” excretory sac, and excretory tube of the nephridium were described. The ultrastructural features of the excretory epithelium, cupola-shaped epithelial infoldings, excretory canals, and muscular layer in the extracellular matrix of the nephridial wall were examined and described in detail. The ultrastructure of the nephridial coelomic epithelium composed of podocytes with long processes and multiciliary cells was also examined and illustrated. Characteristic cell contacts between the processes of podocytes, viz., paired “double diaphragms,” were described and illustrated for the first time.
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peanut worms of the phylum Sipuncula from the sea of japan with a key to species
Deep-sea Research Part Ii-topical Studies in Oceanography, 2013Co-Authors: Andrey V. Adrianov, Anastassya S MaiorovaAbstract:Abstract Sipunculan worms from the Russian waters of the Sea of Japan are still poorly investigated while they are much better known from the Japanese coast. The aim of this paper is to describe Sipunculans from the Russian coast and from the deepest part of the Sea of Japan near the Primorye Province collected by SoJaBio expedition, and to provide keys for identification of Sipunculan species from the Sea of Japan. At the Russian coast of the Sea of Japan only 8 valid species of Sipunculans were found and identified: Golfingia margaritacea , G. vulgaris , Nephasoma capilleforme , N. wodjanizkii , Phascolion strombus , Thysanocardia nigra , Themiste hexadactyla ( =T. pyroides ), Phascolosoma agassizii . Taking into account 4 other valid species noted for this area, Nephasoma eremite , Thysanocardia catharinae , Themiste blanda and Phascolosoma scolops , which were not found, the Sipunculan fauna of the Russian waters of the Sea of Japan now comprises 12 valid species. Nephasoma capilleforme and Nephasoma wodjanizkii are the first records for the North-West Pacific and the Sea of Japan. Species accounts include the most important taxonomic characters and specific biotope data. Accordingly, a key up to species level is provided. Totally, the fauna of the Sea of Japan is now estimated as having 31 valid species of Sipunculans.
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microscopic anatomy and ultrastructure of nephridium in the Sipunculan thysanocardia nigra ikeda 1904 from the sea of japan
2002Co-Authors: Andrey V. Adrianov, A S Maiorova, Volodymyrovych Vladyslav MalakhovAbstract:The microscopic anatomy and ultrastructure of nephridium have been studied in the Sipunculan Thysanocardia nigra Ikeda, 1904 (Sipuncula, Sipunculidea) from the Sea of Japan using histological and electron microscopic techniques (SEM and TEM). This paper describes ultrastructural features of nephridial epithelium, muscle grid, and coelomic epithelium on the surface of the nephridium, the area of the ciliary funnel, and the “tongue.” Several types of cells were distinguished in the excretory tube of the nephridium: (1) a columnar epithelium of the excretory bunches; (2) a cubical or flattened epithelium of flask-shaped infoldings; and (3) granulocytes that migrate from the coelom to the extracellular matrix of the nephridial wall. The system of podocytes and multiciliary cells were described in the nephridial coelothelium. Two types of secretion of nephridial epithelium have been discovered: a merocrine secretion of columnar cells and an apocrine secretion of cells of the flask-shaped infoldings. Using ultrastructural data, two zones of filtration through the wall of excretory tube have been found, namely (1) the tips of flask-shaped infoldings (via the extracellular matrix and microvillary canals between the epithelial cells) and (2) areas between the flask-shaped infoldings (via the contacts of podocytes, extracellular matrix, and the basal labyrinth of the columnar cells). Unlike previously studied representatives of the genus Phascolosoma, no coelomic epithelium is present on the tips of the flask-shaped infoldings in Th. nigra. This data on the anatomy and histology allow us to conclude that the funnel only works like a gonoduct.
A S Maiorova - One of the best experts on this subject based on the ideXlab platform.
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Deep-sea Sipunculans (Sipuncula) of the northwestern Pacific
Russian Journal of Marine Biology, 2017Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:Based on the available literature data, museum collections, and our own material, a review is presented on Sipunculan species of the northwestern Pacific that occur at depths greater than 500 m. Brief morphological descriptions showing the main characters used in taxonomy and a key for the identification of deep-sea Sipunculans of the northwestern Pacific to species level are proposed. The key includes 22 valid species representing 7 genera and 5 families of Sipuncula.
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the microscopic anatomy and ultrastructure of the contractile vessel in the Sipunculan themiste hexadactyla sato 1930 Sipuncula sipunculidea
Russian Journal of Marine Biology, 2014Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:The microscopic anatomy and ultrastructure of the contractile vessel of the Sipunculan Themiste hexadactyla (Sato, 1930) from Vostok Bay (the Sea of Japan) were studied by histological and electron microscope methods. The ultrastructural features of the internal (endothelium) and external (coelothelium) lining of the contractile vessel are described and illustrated. Numerous macromolecular filters, the so-called “double diaphragms,” were found in the external coelothelium facing the cavity of the trunk coelom. This suggests a possible filtration from the tentacular coelom into the trunk coelom though the contractile vessel wall. The microscopic peculiarities of the main tube of the contractile vessel and its numerous lateral branches twining around several internal organs are described in detail. The contractile vessel is polyfunctional: it can act as the main reservoir for the cavity fluid during the withdrawal of the tentacular crown and performs the functions of the distribution system in Sipunculans.
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the microscopic anatomy and ultrastructure of the nephridium of the Sipunculan themiste hexadactyla sato 1930 Sipuncula sipunculidea
Russian Journal of Marine Biology, 2014Co-Authors: A S Maiorova, Andrey V. AdrianovAbstract:The microscopic anatomy and ultrastructure of the nephridia of the Sipunculan Themiste hexadactyla (Sato, 1930) from the Sea of Japan were studied by the histological and electron microscopic methods. The fine structures of the ciliary funnel, muscular “tongue,” excretory sac, and excretory tube of the nephridium were described. The ultrastructural features of the excretory epithelium, cupola-shaped epithelial infoldings, excretory canals, and muscular layer in the extracellular matrix of the nephridial wall were examined and described in detail. The ultrastructure of the nephridial coelomic epithelium composed of podocytes with long processes and multiciliary cells was also examined and illustrated. Characteristic cell contacts between the processes of podocytes, viz., paired “double diaphragms,” were described and illustrated for the first time.
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microscopic anatomy and ultrastructure of nephridium in the Sipunculan thysanocardia nigra ikeda 1904 from the sea of japan
2002Co-Authors: Andrey V. Adrianov, A S Maiorova, Volodymyrovych Vladyslav MalakhovAbstract:The microscopic anatomy and ultrastructure of nephridium have been studied in the Sipunculan Thysanocardia nigra Ikeda, 1904 (Sipuncula, Sipunculidea) from the Sea of Japan using histological and electron microscopic techniques (SEM and TEM). This paper describes ultrastructural features of nephridial epithelium, muscle grid, and coelomic epithelium on the surface of the nephridium, the area of the ciliary funnel, and the “tongue.” Several types of cells were distinguished in the excretory tube of the nephridium: (1) a columnar epithelium of the excretory bunches; (2) a cubical or flattened epithelium of flask-shaped infoldings; and (3) granulocytes that migrate from the coelom to the extracellular matrix of the nephridial wall. The system of podocytes and multiciliary cells were described in the nephridial coelothelium. Two types of secretion of nephridial epithelium have been discovered: a merocrine secretion of columnar cells and an apocrine secretion of cells of the flask-shaped infoldings. Using ultrastructural data, two zones of filtration through the wall of excretory tube have been found, namely (1) the tips of flask-shaped infoldings (via the extracellular matrix and microvillary canals between the epithelial cells) and (2) areas between the flask-shaped infoldings (via the contacts of podocytes, extracellular matrix, and the basal labyrinth of the columnar cells). Unlike previously studied representatives of the genus Phascolosoma, no coelomic epithelium is present on the tips of the flask-shaped infoldings in Th. nigra. This data on the anatomy and histology allow us to conclude that the funnel only works like a gonoduct.
Gonzalo Giribet - One of the best experts on this subject based on the ideXlab platform.
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Re-evaluating the phylogeny of Sipuncula through transcriptomics
Molecular phylogenetics and evolution, 2014Co-Authors: Sarah Lemer, Gisele Y. Kawauchi, Michael J. Boyle, Sónia C. S. Andrade, Vanessa L. González, Gonzalo GiribetAbstract:Sipunculans (also known as peanut worms) are an ancient group of exclusively marine worms with a global distribution and a fossil record that dates back to the Early Cambrian. The systematics of Sipunculans, now considered a distinct subclade of Annelida, has been studied for decades using morphological and molecular characters, and has reached the limits of Sanger-based approaches. Here, we reevaluate their family-level phylogeny by comparative transcriptomic analysis of eight species representing all known families within Sipuncula. Two data matrices with alternative gene occupancy levels (large matrix with 675 genes and 62% missing data; reduced matrix with 141 genes and 23% missing data) were analysed using concatenation and gene-tree methods, yielding congruent results and resolving each internal node with maximum support. We thus corroborate prior phylogenetic work based on molecular data, resolve outstanding issues with respect to the familial relationships of Aspidosiphonidae, Antillesomatidae and Phascolosomatidae, and highlight the next area of focus for Sipunculan systematics.
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Sipunculan phylogeny based on six genes, with a new classification and the descriptions of two new families
Zoologica Scripta, 2012Co-Authors: Gisele Y. Kawauchi, Prashant P. Sharma, Gonzalo GiribetAbstract:Kawauchi, G. Y., Sharma, P. P. & Giribet, G. (2012). Sipunculan phylogeny based on six genes, with a new classification and the descriptions of two new families. —Zoologica Scripta, 41, 186–210. The internal phylogeny of Sipuncula has proven elusive, with the monophyly of multiple traditional groups in question. Repeated attempts to infer Sipunculan relationships have attained discordant results, possibly owing to fragmentary molecular sequence data sets. We reassessed the phylogeny of Sipuncula using a six-gene data set and with larger target amplicons of certain loci. We additionally dated the molecular phylogeny employing recently discovered fossil taxa to constrain node ages. Our multilocus data set recovers six major clades of Sipuncula across multiple analytical treatments. Some groups considered suspect in previous studies are vindicated (e.g. Aspidosiphonidae), but most traditional Sipunculan families were recovered as para- or polyphyletic groups, especially Sipunculidae, whose members appear in three distinct clades. To redress the dissonance between the current classification and the phylogeny of Sipuncula, we provide a new classification of the group, wherein (i) we erect two new families, Siphonosomatidae fam. nov. and Antillesomatidae fam. nov.; (ii) Phascolionidae and Themistidae are synonymized with Golfingiidae, new synonymies (iii) Phascolopsis is transferred to Golfingiidae, new familial assignment; and (iv) Lithacrosiphon is synonymized with Aspidosiphon, new synonymy. We observe that the origins of all families recognized are ancient, dating at least to the Mesozoic.
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Are there true cosmopolitan Sipunculan worms? A genetic variation study within Phascolosoma perlucens (Sipuncula, Phascolosomatidae)
Marine Biology, 2010Co-Authors: Gisele Y. Kawauchi, Gonzalo GiribetAbstract:Phascolosoma perlucens is one of the most common intertidal Sipunculan species and has been considered a circumtropical cosmopolitan taxon due to the presence of a long-lived larva. To verify whether P. perlucens is a true cosmopolitan species or a complex of cryptic forms, we examined the population structure and demographics of 56 putative P. perlucens individuals from 13 localities throughout the tropics. Analysis of two mitochondrial markers, cytochrome c oxidase subunit I and 16S rRNA, suggests high levels of genetic differentiation between distantly located populations of P. perlucens . At least four different lineages identified morphologically as P. perlucens were distinguished. These lineages are likewise supported by phylogenetic analysis of the two mitochondrial markers and by the haplotype network analysis. Our results suggest that P. perlucens is a case of overconservative taxonomy, rejecting the alleged cosmopolitanism of P. perlucens . However, cryptic speciation also exists in some areas, including a possible case of geminate species across the Isthmus of Panama.
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Evolutionary relationships within the protostome phylum Sipuncula: a molecular analysis of ribosomal genes and histone H3 sequence data
Molecular phylogenetics and evolution, 2003Co-Authors: Amy Maxmen, Edward B. Cutler, Burnett F King, Gonzalo GiribetAbstract:The phylogenetic relationships of the members of the phylum Sipuncula are investigated by means of DNA sequence data from three nuclear markers, two ribosomal genes (18S rRNA and the D3 expansion fragment of 28S rRNA), and one protein-coding gene, histone H3. Phylogenetic analysis via direct optimization of DNA sequence data using parsimony as optimality criterion is executed for 12 combinations of parameter sets accounting for different indel costs and transversion/transition cost ratios in a sensitivity analysis framework. Alternative outgroup analyses are also performed to test whether they affected rooting of the Sipunculan topology. Nodal support is measured by parsimony jackknifing and Bremer support values. Results from the different partitions are highly congruent, and the combined analysis for the parameter set that minimizes overall incongruence supports monophyly of Sipuncula, but nonmonophyly of several higher taxa recognized for the phylum. Mostly responsible for this is the split of the family Sipunculidae in three main lineages, with the genus Sipunculus being the sister group to the remaining Sipunculans, the genus Phascolopsis nesting within the Golfingiiformes, and the genus Siphonosoma being associated to the Phascolosomatidea. Other interesting results are the position of Phascolion within Golfingiidae and the position of Antillesoma within Aspidosiphonidae. These results are not affected by the loci selected or by the outgroup chosen. The position of Apionsoma is discussed, although more data would be needed to better ascertain its phylogenetic affinities. Monophyly of the genera with multiple representatives (Themiste, Aspidosiphon, and Phascolosoma) is well supported, but not the monophyly of the genera Nephasoma or Golfingia. Interesting phylogeographic questions arise from analysis of multiple representatives of a few species.
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Reconstructing the phylogeny of the Sipuncula
Developments in Hydrobiology, 1Co-Authors: Anja Schulze, Edward B. Cutler, Gonzalo GiribetAbstract:Sipunculans are marine spiralian worms with possible close affinities to the Mollusca or Annelida. Currently 147 species, 17 genera, 6 families, 4 orders and 2 classes are recognized. In this paper we review Sipunculan morphology, anatomy, paleontological data and historical affiliations. We have conducted cladistic analyses for two data sets to elucidate the phylogenetic relationships among Sipunculan species. We first analyzed the relationships among the 45 species of Phascolosomatidea with representatives of the Sipunculidea as outgroups, using 35 morphological characters. The resulting consensus tree has low resolution and branch support is low for most branches. The second analysis was based on DNA sequence data from two nuclear ribosomal genes (18S rRNA and 28S rRNA) and one nuclear protein-coding gene, histone H3. Outgroups were chosen among representative spiralians. In a third analysis, the molecular data were combined with the morphological data. Data were analyzed using parsimony as the optimality criterion and branch support evaluated with jackknifing and Bremer support values. Branch support for outgroup relationships is low but the monophyly of the Sipuncula is well supported. Within Sipuncula, the monophyly of the two major groups, Phascolosomatidea and Sipunculidea is not confirmed. Of the currently recognized families, only Themistidae appears monophyletic. The Aspidosiphonidae, Phascolosomatidae and Golfingiidae would be monophyletic with some adjustments in their definition. The Sipunculidae is clearly polyphyletic, with Sipunculus nudus as the sister group to the remaining Sipuncula, Siphonosoma cumanense the sister group to a clade containing Siphonosoma vastumand the Phascolosomatidea, and Phascolopsis gouldi grouping within the Golfingiiformes, as suggested previously by some authors. Of the genera with multiple representatives, only Phascolosoma and Themiste are monophyletic as currently defined. We are aiming to expand our current dataset with more species in our molecular database and more detailed morphological studies.
Christoph Bleidorn - One of the best experts on this subject based on the ideXlab platform.
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illuminating the base of the annelid tree using transcriptomics
Molecular Biology and Evolution, 2014Co-Authors: Anne Weigert, Detlev Arendt, Conrad Helm, Kenneth M. Halanych, Matthias Meyer, Birgit Nickel, Bernhard Hausdorf, Scott R Santos, Gunter Purschke, Christoph BleidornAbstract:Annelida is one of three animal groups possessing segmentation and is central in considerations about the evolution of different character traits. It has even been proposed that the bilaterian ancestor resembled an annelid. However, a robust phylogeny of Annelida, especially with respect to the basal relationships, has been lacking. Our study based on transcriptomic data comprising 68,750-170,497 amino acid sites from 305 to 622 proteins resolves annelid relationships, including Chaetopteridae, Amphinomidae, Sipuncula, Oweniidae, and Magelonidae in the basal part of the tree. Myzostomida, which have been indicated to belong to the basal radiation as well, are now found deeply nested within Annelida as sister group to Errantia in most analyses. On the basis of our reconstruction of a robust annelid phylogeny, we show that the basal branching taxa include a huge variety of life styles such as tube dwelling and deposit feeding, endobenthic and burrowing, tubicolous and filter feeding, and errant and carnivorous forms. Ancestral character state reconstruction suggests that the ancestral annelid possessed a pair of either sensory or grooved palps, bicellular eyes, biramous parapodia bearing simple chaeta, and lacked nuchal organs. Because the oldest fossil of Annelida is reported for Sipuncula (520 Ma), we infer that the early diversification of annelids took place at least in the Lower Cambrian.
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Mitochondrial genome sequence and gene order of Sipunculus nudus give additional support for an inclusion of Sipuncula into Annelida
BMC genomics, 2009Co-Authors: Adina Mwinyi, Thomas Bartolomaeus, Christoph Bleidorn, Achim Meyer, Bernhard Lieb, Lars PodsiadlowskiAbstract:Mitochondrial genomes are a valuable source of data for analysing phylogenetic relationships. Besides sequence information, mitochondrial gene order may add phylogenetically useful information, too. Sipuncula are unsegmented marine worms, traditionally placed in their own phylum. Recent molecular and morphological findings suggest a close affinity to the segmented Annelida. The first complete mitochondrial genome of a member of Sipuncula, Sipunculus nudus, is presented. All 37 genes characteristic for metazoan mtDNA were detected and are encoded on the same strand. The mitochondrial gene order (protein-coding and ribosomal RNA genes) resembles that of annelids, but shows several derivations so far found only in Sipuncula. Sequence based phylogenetic analysis of mitochondrial protein-coding genes results in significant bootstrap support for Annelida sensu lato, combining Annelida together with Sipuncula, Echiura, Pogonophora and Myzostomida. The mitochondrial sequence data support a close relationship of Annelida and Sipuncula. Also the most parsimonious explanation of changes in gene order favours a derivation from the annelid gene order. These results complement findings from recent phylogenetic analyses of nuclear encoded genes as well as a report of a segmental neural patterning in Sipuncula.
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Mitochondrial genome sequence and gene order of Sipunculus nudus give additional support for an inclusion of Sipuncula into Annelida
BMC Genomics, 2009Co-Authors: Adina Mwinyi, Thomas Bartolomaeus, Christoph Bleidorn, Achim Meyer, Bernhard Lieb, Lars PodsiadlowskiAbstract:Background Mitochondrial genomes are a valuable source of data for analysing phylogenetic relationships. Besides sequence information, mitochondrial gene order may add phylogenetically useful information, too. Sipuncula are unsegmented marine worms, traditionally placed in their own phylum. Recent molecular and morphological findings suggest a close affinity to the segmented Annelida. Results The first complete mitochondrial genome of a member of Sipuncula, Sipunculus nudus , is presented. All 37 genes characteristic for metazoan mtDNA were detected and are encoded on the same strand. The mitochondrial gene order (protein-coding and ribosomal RNA genes) resembles that of annelids, but shows several derivations so far found only in Sipuncula. Sequence based phylogenetic analysis of mitochondrial protein-coding genes results in significant bootstrap support for Annelida sensu lato , combining Annelida together with Sipuncula, Echiura, Pogonophora and Myzostomida. Conclusion The mitochondrial sequence data support a close relationship of Annelida and Sipuncula. Also the most parsimonious explanation of changes in gene order favours a derivation from the annelid gene order. These results complement findings from recent phylogenetic analyses of nuclear encoded genes as well as a report of a segmental neural patterning in Sipuncula.
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Annelid phylogeny and the status of Sipuncula and Echiura
BMC evolutionary biology, 2007Co-Authors: Torsten H. Struck, Christoph Bleidorn, Nancy Schult, Tiffany Kusen, Emily Hickman, Damhnait Mchugh, Kenneth M. HalanychAbstract:Annelida comprises an ancient and ecologically important animal phylum with over 16,500 described species and members are the dominant macrofauna of the deep sea. Traditionally, two major groups are distinguished: Clitellata (including earthworms, leeches) and "Polychaeta" (mostly marine worms). Recent analyses of molecular data suggest that Annelida may include other taxa once considered separate phyla (i.e., Echiura, and Sipuncula) and that Clitellata are derived annelids, thus rendering "Polychaeta" paraphyletic; however, this contradicts classification schemes of annelids developed from recent analyses of morphological characters. Given that deep-level evolutionary relationships of Annelida are poorly understood, we have analyzed comprehensive datasets based on nuclear and mitochondrial genes, and have applied rigorous testing of alternative hypotheses so that we can move towards the robust reconstruction of annelid history needed to interpret animal body plan evolution. Sipuncula, Echiura, Siboglinidae, and Clitellata are all nested within polychaete annelids according to phylogenetic analyses of three nuclear genes (18S rRNA, 28S rRNA, EF1α; 4552 nucleotide positions analyzed) for 81 taxa, and 11 nuclear and mitochondrial genes for 10 taxa (additional: 12S rRNA, 16S rRNA, ATP8, COX1-3, CYTB, NAD6; 11,454 nucleotide positions analyzed). For the first time, these findings are substantiated using approximately unbiased tests and non-scaled bootstrap probability tests that compare alternative hypotheses. For echiurans, the polychaete group Capitellidae is corroborated as the sister taxon; while the exact placement of Sipuncula within Annelida is still uncertain, our analyses suggest an affiliation with terebellimorphs. Siboglinids are in a clade with other sabellimorphs, and clitellates fall within a polychaete clade with aeolosomatids as their possible sister group. None of our analyses support the major polychaete clades reflected in the current classification scheme of annelids, and hypothesis testing significantly rejects monophyly of Scolecida, Palpata, Canalipalpata, and Aciculata. Using multiple genes and explicit hypothesis testing, we show that Echiura, Siboglinidae, and Clitellata are derived annelids with polychaete sister taxa, and that Sipuncula should be included within annelids. The traditional composition of Annelida greatly underestimates the morphological diversity of this group, and inclusion of Sipuncula and Echiura implies that patterns of segmentation within annelids have been evolutionarily labile. Relationships within Annelida based on our analyses of multiple genes challenge the current classification scheme, and some alternative hypotheses are provided.
Anastassya S Maiorova - One of the best experts on this subject based on the ideXlab platform.
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Proceedings of the Second International Symposium on the Biology of the Sipuncula
Smithsonian Contributions to the Marine Sciences, 2018Co-Authors: Michael J. Boyle, Alen Kristof, Anastassya S Maiorova, Andreas Wanninger, Gisele Y. Kawauchi, Mary E. Rice, Katrine Worsaae, Julianne Piraino, Hugh E. Reichardt, Anja SchulzeAbstract:In June 1970, a diverse group of scientists attended the International Symposium on the Biology of the Sipuncula and Echiura at the Marine Biological Station in Kotor, Yugoslavia. Forty-two years later, in June 2012, an aspiring generation of like-minded scientists convened the Second International Symposium on the Biology of the Sipuncula (ISBS2) along the banks of the Fort Pierce Inlet to the Indian River Lagoon in Fort Pierce, Florida, USA. The primary objective of the second symposium was to convene the world’s dedicated Sipunculan biologists in one place for a long-overdue face-to-face communication of past, present, and future research. This proceedings volume includes a brief summary of workshop discussions and field events as well as a compilation of selected research papers presented by an international group of 16 scientists from 12 nations in attendance at the ISBS2. Herein, we highlight molecular, developmental, morphological, ecological, and biogeographic diversity of adult and larval Sipunculans. In addition, we introduce several of the outstanding research challenges associated with resolving Sipunculan interrelationships, establishing standard sets of taxonomic characters, refining methods for identification of cryptic species, reconstructing an evolutionary framework of developmental life history patterns, and addressing implications of recent phylogenetic and phylogenomic hypotheses that have relocated the ancient radiation of unsegmented Sipunculan body plans within the predominantly segmented Annelida. Collectively, although we represent a small group of Sipunculan biologists (of whom a matching number did not attend the ISBS2), we hope this volume will not only draw attention to an intriguing and notably understudied clade of marine worms but also attract new researchers to help us promote them as valuable experimental models and to include them among broader interdisciplinary efforts to better understand the biological diversity of marine invertebrate animals worldwide. Smithsonian Contributions to the Marine Sciences , number 42, x + 235 pages, 151 figures, 23 tables, 2018.
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Golfingicola abyssalis gen. et sp. nov., a new endoparasitic copepod (Crustacea) in a Sipunculan from abyssal depths of the Northwest Pacific Ocean
Deep Sea Research Part II: Topical Studies in Oceanography, 2015Co-Authors: E Schwabe, Anastassya S MaiorovaAbstract:Abstract Marine copepods, which inhabit the entire water column down to the seafloor, are key contributors to the food web, mainly providing a food source for many organisms in the form of zooplankton. Furthermore, they also play an important ecological role as associates or even parasites with various degrees of harm to their hosts. Copepods are found in almost all habitats and can be associated with virtually every metazoan group. A female and four males of a new endoparasitic copepod genus and species ( Golfingicola abyssalis ) are described from the trunk celom of the Sipunculan Golfingia muricaudata (Southern, 1913), collected from the abyssal depths of the Northwest Pacific Ocean near the Kuril–Kamchatka Trench. This Sipunculan species is a typical deep sea representative of the northwestern Pacific region, occurring in the Bering Sea and the abyssal regions east of the Kuril Island chain. Despite numerous records of this species, a copepod association has not been reported prior to this paper. The new parasitic copepod species is tentatively placed in the Akessonia group given its endoparasitic behavior in Sipuncula, the elongated shape, the enlarged egg strings, and the presence of subchelate antenna, as well as lateral processes in males. Golfingicola abyssalis , however, shows some peculiarities that clearly differentiate it from the remaining endoparasites in Sipuncula. As the first abyssal endoparasite in Sipuncula, the species is characterized by the complete lack of any processes in females, the presence of a mandible in females, a weakly defined prosome–urosome boundary in females, the presence of a mouth in males, the free living behavior of males, a distinctly reduced number of trunk processes in males, as well as a more modified male antenna, displaying an endopodite and a highly modified setal element. A detailed review on the morphological characters of the four species currently grouped in the Akessonia group, and systematic and biogeographic information of their relevant host taxa is provided. On the basis of morphological and ecological similarities, the new species seems to be more closely related to the northern Atlantic Akessonia occulta Bresciani and Luetzen, 1962 than to Siphonobius gephyreicola Augener, 1903 and Coelotrophus nudus Ho et al., 1981.
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peanut worms of the phylum Sipuncula from the sea of japan with a key to species
Deep-sea Research Part Ii-topical Studies in Oceanography, 2013Co-Authors: Andrey V. Adrianov, Anastassya S MaiorovaAbstract:Abstract Sipunculan worms from the Russian waters of the Sea of Japan are still poorly investigated while they are much better known from the Japanese coast. The aim of this paper is to describe Sipunculans from the Russian coast and from the deepest part of the Sea of Japan near the Primorye Province collected by SoJaBio expedition, and to provide keys for identification of Sipunculan species from the Sea of Japan. At the Russian coast of the Sea of Japan only 8 valid species of Sipunculans were found and identified: Golfingia margaritacea , G. vulgaris , Nephasoma capilleforme , N. wodjanizkii , Phascolion strombus , Thysanocardia nigra , Themiste hexadactyla ( =T. pyroides ), Phascolosoma agassizii . Taking into account 4 other valid species noted for this area, Nephasoma eremite , Thysanocardia catharinae , Themiste blanda and Phascolosoma scolops , which were not found, the Sipunculan fauna of the Russian waters of the Sea of Japan now comprises 12 valid species. Nephasoma capilleforme and Nephasoma wodjanizkii are the first records for the North-West Pacific and the Sea of Japan. Species accounts include the most important taxonomic characters and specific biotope data. Accordingly, a key up to species level is provided. Totally, the fauna of the Sea of Japan is now estimated as having 31 valid species of Sipunculans.
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Cellular and muscular growth patterns during Sipunculan development.
Journal of experimental zoology. Part B Molecular and developmental evolution, 2011Co-Authors: Alen Kristof, Tim Wollesen, Anastassya S Maiorova, Andreas WanningerAbstract:Sipuncula is a lophotrochozoan taxon with annelid affinities, albeit lacking segmentation of the adult body. Here, we present data on cell proliferation and myogenesis during development of three Sipunculan species, Phascolosoma agassizii, Thysanocardia nigra, and Themiste pyroides. The first anlagen of the circular body wall muscles appear simultaneously and not subsequently as in the annelids. At the same time, the rudiments of four longitudinal retractor muscles appear. This supports the notion that four introvert retractors were part of the ancestral Sipunculan bodyplan. The longitudinal muscle fibers form a pattern of densely arranged fibers around the retractor muscles, indicating that the latter evolved from modified longitudinal body wall muscles. For a short time interval, the distribution of S-phase mitotic cells shows a metameric pattern in the developing ventral nerve cord during the pelagosphera stage. This pattern disappears close to metamorphic competence. Our findings are congruent with data on Sipunculan neurogenesis, as well as with recent molecular analyses that place Sipuncula within Annelida, and thus strongly support a segmental ancestry of Sipuncula.
