Deep-water Buccinidae (Gastropoda: Neogastropoda) from sunken wood, vents and seeps: molecular phylogeny and taxonomy

Buccinidae-like other canivorous and predatory molluscs-are generally considered to be occasional visitors or rare colonizers in deep-sea biogenic habitats. However, casual observations during tropical deep-sea cruises suggest that associations between buccinids and sunken wood, in particular, are not fortuitous. Enigmatocolus monnieri has been found to co-occur in Madagascar with bathymodiolines, vesicomyids and solemyids, indicating the presence of seeps, and species of Thermosipho gen. nov. have been sampled by submersibles and remotely operated vehicles, exclusively from hydrothermal vents. A molecular phylogeny (based on CO1, 12S and 28S genes) reveals that buccinid genera potentially associated with sunken wood (Eosipho, Gaillea gen. nov., Calagrassor gen. nov., and Manaria) are closely related to taxa from vents (Thermosipho gen. nov.) and seeps (Enigmaticolus). The anatomy of several dissected species did not reveal any special trait that could be interpreted as a special adaptation to biogenic substrates. Buccinids from sunken wood are most diverse in the Indo-Pacific centre of marine biodiversity, the 'Coral Triangle', at depths between 100 and 1000 m, with numerous species still undescribed.