A new deep-sea species of spaghetti worms (Annelida, Terebellidae) from Walters Shoal, SE Indian Ocean

Abstract

During an oceanographic campaign led by the Museum National d’Histoire Naturelle and the Institut de Recherche pour le Développement to explore the biodiversity of Walters Shoal Seamount in the Indian Ocean, a new species of Morgana was discovered. Until now, this genus was monotypic with the only known species described from shallow waters off São Paulo, south-eastern Brazil: M. bisetosa Nogueira & Amaral, 2001. This new deep-sea species, M. waltershoalensis sp. nov., is characterised by the absence of branchiae, the notopodia beginning from segment 4 and the neuropodia from the 6th, a great number of segments with notopodia ( n  = 53), and the presence of a pair of large nephridial papillae dorsally, on segment 3. This species differs from M. bisetosa by the absence of eyespots, the shape of both noto- and neurochaetae and by the presence of a large pair nephridial papillae on the third segment. Following this study, the boundaries of the genus have been modified, particularly with regard to the number of segments with notopodia, the presence of eyespots and the large papilla on segment 3.