Two new Antarctic Ophryotrocha (Annelida: Dorvilleidae) described from shallow-water whale bones

Abstract

Marine invertebrate fauna associated with whale remains has lately attracted a great deal of interest. However, very little is known about this fauna in the Southern Ocean, an area with high abundances of cetaceans. To investigate the Antarctic organisms associated with these substrates, we conducted a study using whale bones in the shallow-waters of Deception Island (South Shetland Islands). In this paper, we describe two new species of Ophryotrocha (O. orensanzi sp. nov. and O. clava sp. nov.) from a minke whale (Balaenoptera acutorostrata) fresh caudal vertebra experimentally deployed for about a year and from an unknown whale vertebra presumably dating back to the early twentieth century whaling operations. Ophryotrocha clava sp. nov., found in relative high abundance in the fresh bone, is hypothesized to be an opportunistic species in the context of Antarctic shallow-water organically enriched environments. Ophryotrocha orensanzi sp. nov. appears to be the same species as the unnamed Palpiphitime sp., near lobifera, formerly reported from a nearby area. Phylogenetic analyses based on the nuclear gene H3 and the mitochondrial genes COI and 16S, using MrBayes and Maximum Likelihood analyses, show that O. clava sp. nov. is close to Iphitime hartmanae and is included in the ‘hartmanni’ clade, while O. orensanzi sp. nov. falls in the ‘lobifera’ clade. Remarks about their feeding preferences and ecology are also given. Our findings seem to suggest that members of the genus Ophryotrocha are important components of organically enriched Southern Ocean environments, as has been reported for this clade in other geographic areas.