Chrysopetalidae (Annelida: Phyllodocida) from the Senghor Seamount, north-east Atlantic: taxa with deep-sea affinities and morphological adaptations

Abstract

Watson, C., Chivers, A.J., Narayanaswamy, B.E., Lamont, P. and Turnewitsch, R. 2014. Chrysopetalidae (Annelida: Phyllodocida) from the Senghor Seamount, north-east Atlantic: taxa with deep-sea affinities and morphological adaptations. Memoirs of Museum Victoria 71: 311–325. Senghor Seamount is located in the north-east (NE) Atlantic Ocean, 550 km west of Senegal, Africa, in the Cape Verde Archipelago. Macrofaunal sampling was undertaken from the summit (~100 m depth) to the base of the seamount (~3300 m depth) during the RV Meteor cruise (November 2009). The Chrysopetalidae fauna represents the first record for the family from a tall seamount habitat and is composed of East Atlantic continental margin and deep-sea species. Dysponetus sp. 1 is present at the summit and Dysponetus caecus at base depths. Thrausmatos is recorded for the first time in the Atlantic Ocean, as Thrausmatos senghorensis sp. nov., and is found at mid-slope depths only. The taxon with the largest number of individuals, Arichlidon reyssi, is most evident at the summit, with one record mid-slope. All Senghor species belong to the only three chrysopetalid genera that possess epitokous, swimming neurochaetae. Adults of A. reyssi from the Senghor Seamount and planktonic metatrochophore larvae from the NE Atlantic coast are compared and described in detail. The West Atlantic benthic nectochaete larvae of Arichlidon gathofi are also described in the interest of recognising and separating the two cryptic Atlantic Arichlidon species.