On the identity of two Antarctic brooding nemerteans: redescription of Antarctonemertes valida (Bürger, 1893) and description of a new species in the genus Antarctonemertes Friedrich, 1955 (Nemertea, Hoplonemertea)


Nemerteans (ribbon worms) constitute an abundant and occasionally conspicuous group of benthic invertebrates in the Southern Ocean. Although recent work has confirmed that this group is far more diverse than previously recognized, the Antarctic nemertean fauna remains poorly understood when compared to other geographic regions. In most cases, the taxonomic information on the known nemertean fauna is incomplete for this region and/or has been inappropriately documented. As a consequence, many of the species described are considered species inquirendae. Among the nearly 50 species described so far for the Southern Ocean, two hoplonemerteans are known to brood eggs in cocoons: Amphiporus incubator Joubin, 1914 and Amphiporus michaelseni Bürger, 1895a. Here, we redescribe Antarctonemertes valida (Bürger, 1893), a senior synonym of A. michaelseni, and describe a new congeneric species, Antarctonemertes riesgoae sp. nov. Both species show a similar reproductive strategy by brooding their cocoons, and similar external appearance, but clearly differ in other aspects of their morphology, such as the cephalic coloration pattern and the number of proboscidial nerves. We provide novel information about their life habitus, reproductive behaviour, internal anatomy, and their phylogenetic placement within hoplonemerteans using one nuclear (28S rRNA) and two mitochondrial [cytochrome c oxidase subunit I (COI) and 16S rRNA] markers. We also provide a parsimony haplotype network using 16S rRNA, COI, and the internal transcribed spacer region 2 (ITS-2) showing a clear distinction between individuals of both species. Our results stress the need of combining molecular and morphological information when dealing with closely related species of nemerteans.

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We are deeply obliged to the “Gabriel de Castilla” Antarctic Spanish Base crew of the 2009-2010 season for their unconditional help. We are more grateful to our ACTIQUIM project colleagues: L. Núñez, B. Figuerola, and J. Vázquez, and especially to M. Ballesteros who provided the specimens from King George Island. We would also like to thank the members of the Giribet lab (Harvard University), who helped during the genetic work, especially A. Riesgo and M. Novo. Editor Dieter Piepenburg, Hiroshi Kajihara, and two additional anonymous reviewers are acknowledged for their comments, which helped to improve a previous version of this manuscript. This research received support from the Spanish Government, through the research projects ACTIQUIM-I and II (CGL2007-65453/ANT, CTM2010-17415/ANT) as well as from Banco Popular. Molecular work was supported by internal funds from the Museum of Comparative Zoology.

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Taboada, S., Junoy, J., Andrade, S.C.S. et al. On the identity of two Antarctic brooding nemerteans: redescription of Antarctonemertes valida (Bürger, 1893) and description of a new species in the genus Antarctonemertes Friedrich, 1955 (Nemertea, Hoplonemertea). Polar Biol 36, 1415–1430 (2013).

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  • Taxonomy
  • Phylogeny
  • Deception Island
  • Character matrix
  • Haplotype network