Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov.
Recent advances in taxonomy have disclosed the prevalence of cryptic sibling species in marine systems. In didemnid ascidians, morphological variation between species is often slight, and many species may have been overlooked. Species boundaries within this group are often equivocal, and patterns am...
Published in: | Canadian Journal of Zoology |
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Canadian Science Publishing
1996
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Online Access: | http://dx.doi.org/10.1139/z96-043 http://www.nrcresearchpress.com/doi/pdf/10.1139/z96-043 |
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crcansciencepubl:10.1139/z96-043 2024-06-23T07:52:46+00:00 Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. Marks, Jessica A. 1996 http://dx.doi.org/10.1139/z96-043 http://www.nrcresearchpress.com/doi/pdf/10.1139/z96-043 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Zoology volume 74, issue 2, page 357-379 ISSN 0008-4301 1480-3283 journal-article 1996 crcansciencepubl https://doi.org/10.1139/z96-043 2024-05-24T13:05:53Z Recent advances in taxonomy have disclosed the prevalence of cryptic sibling species in marine systems. In didemnid ascidians, morphological variation between species is often slight, and many species may have been overlooked. Species boundaries within this group are often equivocal, and patterns among taxa are reminiscent of those formed by reticulate evolution in plants. Specimens of the sessile colonial ascidian Didemnum albidum (Verrill, 1871) were examined for life-history and morphological characters and found to constitute at least three sympatric sibling species. One of these, Didemnum romssae, is described here as a new species. Colonies were collected from hard-bottom assemblages in Troms and Finnmark counties in northern Norway. Zooid morphology in D. romssae is similar to that of D. albidum, but varies within each species, even for traits usually considered specific. Didemnum romssae is proposed as a distinct species on the basis of consistent differences in (i) the shape and size of calcium carbonate spicules within the common test; (ii) larval size and the number of lateral ampullae; (iii) timing of reproduction; and (iv) the absence of a seasonal nonfeeding, overwintering stage, which occurs in D. albidum. Examination of specimens from museum collections considered synonymous with D. albidum confirmed the presence of a third species, Didemnum polare (Hartmeyer, 1903), which differed from the other two species in zooid and larval morphology as well as spicule shape. Complexes of sibling species such as these provide a tractable system for studying the consequences of life-history variation among closely related taxa. Article in Journal/Newspaper Finnmark Northern Norway Finnmark Troms Canadian Science Publishing Norway Canadian Journal of Zoology 74 2 357 379 |
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Open Polar |
collection |
Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
Recent advances in taxonomy have disclosed the prevalence of cryptic sibling species in marine systems. In didemnid ascidians, morphological variation between species is often slight, and many species may have been overlooked. Species boundaries within this group are often equivocal, and patterns among taxa are reminiscent of those formed by reticulate evolution in plants. Specimens of the sessile colonial ascidian Didemnum albidum (Verrill, 1871) were examined for life-history and morphological characters and found to constitute at least three sympatric sibling species. One of these, Didemnum romssae, is described here as a new species. Colonies were collected from hard-bottom assemblages in Troms and Finnmark counties in northern Norway. Zooid morphology in D. romssae is similar to that of D. albidum, but varies within each species, even for traits usually considered specific. Didemnum romssae is proposed as a distinct species on the basis of consistent differences in (i) the shape and size of calcium carbonate spicules within the common test; (ii) larval size and the number of lateral ampullae; (iii) timing of reproduction; and (iv) the absence of a seasonal nonfeeding, overwintering stage, which occurs in D. albidum. Examination of specimens from museum collections considered synonymous with D. albidum confirmed the presence of a third species, Didemnum polare (Hartmeyer, 1903), which differed from the other two species in zooid and larval morphology as well as spicule shape. Complexes of sibling species such as these provide a tractable system for studying the consequences of life-history variation among closely related taxa. |
format |
Article in Journal/Newspaper |
author |
Marks, Jessica A. |
spellingShingle |
Marks, Jessica A. Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
author_facet |
Marks, Jessica A. |
author_sort |
Marks, Jessica A. |
title |
Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
title_short |
Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
title_full |
Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
title_fullStr |
Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
title_full_unstemmed |
Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov. |
title_sort |
three sibling species of didemnid ascidians from northern norway: didemnum albidum (verrill, 1871), didemnum polare (hartmeyer, 1903), and didemnum romssae sp.nov. |
publisher |
Canadian Science Publishing |
publishDate |
1996 |
url |
http://dx.doi.org/10.1139/z96-043 http://www.nrcresearchpress.com/doi/pdf/10.1139/z96-043 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Finnmark Northern Norway Finnmark Troms |
genre_facet |
Finnmark Northern Norway Finnmark Troms |
op_source |
Canadian Journal of Zoology volume 74, issue 2, page 357-379 ISSN 0008-4301 1480-3283 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/z96-043 |
container_title |
Canadian Journal of Zoology |
container_volume |
74 |
container_issue |
2 |
container_start_page |
357 |
op_container_end_page |
379 |
_version_ |
1802644148880146432 |