A new species of Neostygarctus (Arthrotardigrada) from the Condor Seamount in the Azores, Northeast Atlantic

Abstract

The tardigrade fauna of Condor Seamount, west of the Azores, is relatively rich, and species from at least seven genera are represented. A new species of the rare marine genus Neostygarctus (Arthrotardigrada) was found at 206 m depth at the summit of the seamount. This is the first record of the genus from the Atlantic Ocean, and also the deepest record of the genus. The new species Neostygarctus oceanopolis sp. nov. is easily distinguished from the Mediterranean type species N. acanthophorus by the number of middorsal spines. N. acanthophorus has five dorsal spines, whereas the adult of N. oceanopolis sp. nov. has seven. The cave tardigrade from Japan, Neostygarctus lovedeluxe also has dorsal spines on all five segments, but only the cephalic and the caudal segments have a middorsal spine, while the three other trunk segments have two spines on each of the dorsal segmental body plates. For the first time, ventral plates are recorded for a species of Neostygarctus. A membranous coating of the all spines of the cephalic segment, the lateral processes of the first three trunk segments, and the spines of the fourth leg pair are unique for Neostygarctus.