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An Externally Brooding Acorn Worm (Hemichordata, Enteropneusta, Torquaratoridae) from the Russian Arctic

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dc.contributor.author Osborn, Karen J. en
dc.contributor.author Gebruk, Andrey V. en
dc.contributor.author Rogacheva, Antonina en
dc.contributor.author Holland, Nicholas D. en
dc.date.accessioned 2017-11-16T19:30:50Z
dc.date.available 2017-11-16T19:30:50Z
dc.date.issued 2013
dc.identifier.citation Osborn, Karen J., Gebruk, Andrey V., Rogacheva, Antonina, and Holland, Nicholas D. 2013. "<a href="https://repository.si.edu/handle/10088/33984">An Externally Brooding Acorn Worm (Hemichordata, Enteropneusta, Torquaratoridae) from the Russian Arctic</a>." <em>Biological Bulletin</em>. 225 (2):113&ndash;123. en
dc.identifier.issn 0006-3185
dc.description.abstract A single specimen of a previously undescribed acorn worm in the family Torquaratoridae was trawled from a bottom depth of about 350 m in the Kara Sea (Russian Arctic). The new species is the shallowest of the exclusively deep-sea torquaratorids found to date, possibly an example of high-latitude emergence. On the basis of ribosomal DNA sequences and morphology, the worm is described here as the holotype of Coleodesmium karaensis n. gen., n. sp. It is most similar in overall body shape to the previously described enteropneust genus Allapasus, but is uniquely characterized by a tubular component of the proboscis skeleton ensheathing the collar nerve cord. Additionally, within the proboscis, the sparseness of the musculature of C. karaensis clearly distinguishes it from the much more muscular members of Allapasus. The holotype is a female bearing about a dozen embryos on the surface of her pharyngeal region, each recessed within a shallow depression in the dorsal epidermis. The embryos, ranging from late gastrula to an early stage of coelom formation, are a little more than 1 mm in diameter and surrounded by a thin membrane. Each embryo comprises an external ectoderm of monociliated cells (not arranged in obvious ciliated bands) and an internal endo-mesoderm; the blastopore is closed. In the most advanced embryos, the anterior coelom is starting to constrict off from the archenteron. Coleodesmium karaensis is the first enteropneust (and indeed the first hemichordate) found brooding embryos on the surface of the mother&#39;s body. en
dc.relation.ispartof Biological Bulletin en
dc.title An Externally Brooding Acorn Worm (Hemichordata, Enteropneusta, Torquaratoridae) from the Russian Arctic en
dc.type Journal Article en
dc.identifier.srbnumber 117818
rft.jtitle Biological Bulletin
rft.volume 225
rft.issue 2
rft.spage 113
rft.epage 123
dc.description.SIUnit NH-Invertebrate Zoology en
dc.description.SIUnit NMNH en
dc.description.SIUnit Peer-reviewed en
dc.citation.spage 113
dc.citation.epage 123

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