Is the Antarctic Ophryotrocha orensanzi (Annelida: Dorvilleidae) a circumpolar non-specialized opportunist?

Abstract

The dorvilleid polychaete Ophryotrocha orensanzi is reported from the vicinity of Casey station, East Antarctica, an astounding range extension from its previous records in the South Shetland Islands to the opposite side of the Antarctic continent, suggesting that it is a circumpolar species. Genetic studies confirmed the conspecificity and the inferred haplotype network suggests that the two populations studied are genetically connected. Morphological studies of the newly collected material revealed that the jaw apparatus consists of the P- and K-type, in accordance with other members of the ‘lobifera’ clade. We are reporting a previously undocumented button-like structure that we are referring to as ‘nuchal papilla’ for its association with the nuchal region, and present an emended diagnosis for the species. The Casey station population was collected in a clean, unpolluted intertidal environment associated with stones and seaweeds. We are challenging the generally held opinion that Ophryotrocha species are specialists of organically enriched substrates, suggesting that, at least for the particulars of O. orensanzi, they might also be unspecialized opportunists, able to exist in the most pristine environments and having the ability to rapidly increase their population sizes under favourable conditions.

Key words:

• Antarctica
• Casey station
• Deception Island
• haplotype network
• K-type maxillae
• morphology
• nuchal papilla
• polychaete

Acknowledgements

We are grateful to the Australian Antarctic Division for the provision of specimens. Many thanks go to Sue Lindsay (AM) for assistance with SEM. Special thanks are given to the Gabriel de Castilla Spanish Antarctic Base crews of the 2008–2009, 2009–10, 2011–12 and 2012–13 seasons for their help during deployment and recovery of the experiments. We are more than grateful to our colleagues C. Avila, A. Riesgo, M. Bas, J. Cristobo, J. Moles, C. Angulo, B. Figuerola, and L. Núñez-Pons who helped during sample collection and processing. This paper is part of the AntEco (State of the Antarctic Ecosystem) Scientific Research Programme.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: http://dx.doi.org/10.1080/14772000.2016.1218371.

Additional information

Funding

This research was funded by the Spanish Government, under the research project ACTIQUIM-II (CTM2010-17415/ANT) and by Natural History Museum internal funding to A. Riesgo (SDF14032). Collections from Casey station were supported by the Australian Government through Australian Antarctic Science Grants awarded to P. Harrison (AAS 4142) and to C. K. King (AAS 4100).