Description of a new genus and species of Chrysopetalidae (Annelida: Polychaeta) from the NE Atlantic, with some further records of related species

Abstract

Five chrysopetalid species are reported from samples collected at bathyal depths in three NE Atlantic regions: the Bay of Biscay, the Horseshoe Abyssal Plain and the Gulf of Cadiz. Arichlidon reyssi (Katzmann et al., 1974), Dysponetus caecus (Langerhans, 1880) and D. profundus Böggemann, 2009 are free-living forms found mainly on biogenic substrates (e.g., coral and sunken wood). A brief description and taxonomical remarks are given for each of these species and their geographical distributions and habitat records were updated accordingly. Natsushima bifurcata Miura & Laubier, 1990 and Craseoschema thyasiricola gen. et sp. nov. are symbionts inhabiting the mantle cavity of chemosynthesis-based bivalves known from four mud volcanoes from the Gulf of Cadiz. Craseoschema thyasiricola gen. et sp. nov. was found inside a thyasirid bivalve and presents mixed morphological characteristics of free-living and symbiotic forms within Calamyzinae Hartmann-Schröder, 1971. A full description of the new species is given together with DNA sequences of the genes COI, 16S and H3 that were used in a phylogenetic analysis to indicate the position of the new genus within the family ; Financial support was provided by CESAM (UID/AMB/50017/2019) and by FCT/MCTES (Fundação para a Ciência e a Tecnologia /Ministério de Ciência, Tecnologia e Ensino Superior) through national funds. AR was supported by a postdoctoral grant (SFRH/BPD/112408/2015) from FCT co-financed by ESF (European Science Foundation) and MEC (Ministério da Fundação e Ciência). CR and LG were supported by postdoctoral grants, SFRH/BPD/107805/2015 and SFRH/ BPD/96142/2013, respectively. This study is a contribution of the "Macroevolutionary Transitions in Syllidae" Project (CGL2015-63593-P), supported by MINECO/FEDER (Ministério de Economia y Competitividad/Fondo Europeo de Desarrollo Regional) and European Union funds (PI: MTA)