First columbellid species (Gastropoda: Buccinoidea) from deep-sea hydrothermal vents, discovered in Okinawa Trough, Japan

Abstract

The molluscan diversity of deep-sea chemosynthetic ecosystems in Japan has been in general well documented with about 80 described species, of which over half are gastropods (Sasaki et al. 2005; Fujikura et al. 2012; Sasaki et al. 2016). Recently, however, a number of novel hydrothermal vent sites were discovered in the area using multibeam echosounding (Nakamura et al. 2015), providing opportunities for new discoveries. As a part of ongoing studies documenting the biodiversity of such sites, we present the first record of Columbellidae from hydrothermal vents, with a new species recovered from Natsu and Aki sites, in the Iheya North hydrothermal field (for map and background on the vent field see Nakamura et al. 2015). Columbellidae is a diverse family of caenogastropods in the superfamily Buccinoidea which include 70 genera and several hundred species (deMaintenon 2014; Araya et al. 2016), most of which inhabit shallow waters and carry distinct colour patterns. Generally, columbellids are small in size (mostly less than 20 mm although some large specimens exceed 40 mm) and are either active carnivores or scavengers (Squires 2015). More than 65 species are known from Japan alone (Okutani 2017), although the deep-water diversity of the family remains poorly understood with a number of unnamed species (Hasegawa 2009). The present new species is the first columbellid recorded not only from hydrothermal vent ecosystems in Okinawa Trough, but from global vent communities as a whole. Prior to the present study, the only columbellids reported from chemosynthetic ecosystems have been from whale-falls (Smith et al. 1989; Levin et al. 2002).