Marine gastrotrich fauna in Corsica (France), with a description of a new species of the genus Tetranchyroderma (Macrodasyida, Thaumastodermatidae)

A faunistic analysis of the sandy sediment collected from 10 locations along the east (four) and west coasts (six) of Corsica; western Mediterranean Sea, yielded a rich and diverse range of gastrotrichs: 42 species of 18 genera and seven families from the orders Chaetonotida (17 species) and Macrodasyida (25 species). Sublittoral samples were always more species-rich than those from littoral sites; 37 versus nine spp. The gastrotrich fauna from the east coast was more diverse than that from the west coast, both in terms of the total species number (35 spp.: 13 Chaetonotida + 22 Macrodasyida versus 23 spp.: 12 Chaetonotida + 11 Macrodasyida) and the number of species per location (13 +/- 4.2 versus 7.5 +/- 4.0). All but three of the species have previously been reported from other Mediterranean locations. The exceptions are two as yet unidentified species of the genera Cephalodasys and Macrodasys, and Tetranchyroderma inaequitubutatum sp. nov., a thaumastodermatid with pentancrous covering, showing a cluster of ventral adhesive tubes peculiarly located only on the right side and an unusually conspicuous sexual caudal organ. Aspidiophorus paramediterraneus, Chaetonotus apechochaetus, Acanthodasys aculeatus, Paraturbanella teissieri, Pseudostomella etrusca and Tetranchyroderma thysanophorum, present at 50% or more of the investigated locations, are the most common species on the third largest island of the western Mediterranean basin.