Polychaete meets octopus: symbiotic relationship between Spathochaeta octopodis gen. et sp. nov. (Annelida: Chrysopetalidae) and Octopus sp. (Mollusca: Octopodidae)

Abstract

Marine annelids in the subfamily Calamyzinae (family Chrysopetalidae) are either symbiotic or free-living forms that have been mainly reported from deep-sea chemosynthetic systems. Symbiotic calamyzines mainly live in the mantle cavity of bivalves in hydrothermal vents or cold seeps, but one species is also found to be inserted into the epidermis of polychaetes. We found a single specimen of calamyzine polychaete on the body surface of Octopus sp. collected in the Sea of Kumano (Japan), which represents the first known record of symbiotic association between polychaetes and octopuses. We described the specimen as Spathochaeta octopodis gen. et sp. nov. Spathochaeta gen. nov. can be discriminated from other genera in Calamyzinae by the presence of spatula-shaped notochaetae and dorsal chaetal lobes. We also provided the phylogenetic position of S. octopodis gen. et sp. nov. within Chrysopetalidae based on four gene markers (COI, 16S, 18S, H3). www.zoobank.org/urn:lsid:zoobank.org:pub:A8FB15C1-31A7-4487-966B-13F10E19A373.

Key words:

• marine invertebrates
• Pacific
• parasite
• phylogeny
• Polychaeta
• taxonomy

Acknowledgements

We are grateful to Jinsho Co., Ltd, as well as the crew of the trawler Jinsho-maru XVIII, for collecting the material and to Dr Hidetaka Furuya for preliminarily identifying the octopus specimen.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental material for this article can be accessed at https://doi.org/10.1080/14772000.2018.1520753

Associate Editor: Adrian Glover

Additional information

Funding

This study is partly supported by JSPS KAKENHI No. JP17J05066 to NJ.