The identity of juvenile Polynoidae (Annelida) in the Southern Ocean revealed by DNA taxonomy, with notes on the status of Herdmanella gracilis Ehlers sensu Augener

Using molecular data (CO1, 16S and H3 genes), we provide evidence for a long-held view that Southern Ocean scaleworms (Polynoidae) morphologically agreeing with Herdmanella gracilis sensu Augener, 1929 Ehlers sensu Augener are in fact juveniles of another species. The problematic genus Herdmanella is declared a nomen dubium. Importantly, at least two species were identified; one adult counterpart is a common circumpolar species, Austrolaenilla antarctica Bergström, 1916, and the other is of an as yet unknown identity. More adult counterparts are likely to be discovered with greater sequencing effort and larger taxon coverage. We have discovered a great genetic diversity within the A. antarctica clade in the CO1 gene, and future studies may elucidate if this represents a cryptic species. Currently, we adopt a conservative approach and suggest that given low diversity in mt16S and complete identity in H3 genes, this clade represents a single species, with only the specimen from South Georgia likely deserving the status of a cryptic species, as shown by haplotype network analysis. High mtDNA diversity in populations of Antarctic scaleworms may be linked to habitat fragmentation during recent glacial periods. Our study also highlights the importance of identifying juvenile specimens correctly in order to understand ecological processes such as the apparent high productivity in the Amundsen Sea region.

Details