Marine Gastrotricha of Little Cayman Island with the description of one new species and an initial assessment of meiofaunal diversity

Abstract

Surveys of littoral and sublittoral sediments from diverse marine environments around Little Cayman Island (LCI) have produced the first records of gastrotrichs from one of the most remote West Indian islands in the Greater Antilles ecoregion of the Tropical Northwest Atlantic. Forty-six stations ranging from littoral to 40 m depth yielded 18 morphospecies from 10 genera (7 Macrodasyida, 3 Chaetonotida) representing six families of Gastrotricha. At least one species is new to science and is described here. Oregodasys caymanensis n. sp. is described from multiple stations around the island from 1.5 to 15 m depth. The new species belongs to a group of species with posterior cirri, but can be distinguished by the possession of six rod-like cephalic tentacles on the oral hood and the presence of pigmented y-cells. Nine previously described morphospecies from other Caribbean and global locations were present around LCI: Aspidiophorus cf. paramediterraneus, A. tentaculatus, Chaetonotus aff. apechochaetus, C. cf. atrox, C. cf. dispar (Chaetonotidae); Diplodasys rothei (Thaumastodermatidae); Macrodasys cf. ommatus and Urodasys viviparus (Macrodasyidae); and Paraturbanella pacifica (Turbanellidae). We also encountered further unidentified morphospecies of Chaetonotida from the genus Xenotrichula and from six genera of Macrodasyida (Diplodasys, Megadasys, Macrodasys, Oregodasys, Paraturbanella, Tetranchyroderma). In addition to new geographic records of Gastrotricha, we provide the first general survey of meiofauna from Little Cayman Island including new geographic records for several taxa.