Descriptions of two new species in the genus Macrostylis Sars, 1864 (Isopoda, Asellota, Macrostylidae) from the Weddell Sea (Southern Ocean), with a synonymisation of the genus Desmostylis Brandt, 1992 with Macrostylis

Descriptions of Macrostylis antennamagna sp. n. and M. uniformis sp. n. are presented with notes on intraspecific variability and sexual dimorphism. M. uniformis sp. n. showes differences to M. antennamagna sp. n. in the length of the antenna 2, the shape of the pleotelson and length of uropods. The genus Desmostylis Brandt, 1992 (formerly including the two species D. obscurus Brandt, 1992 and D. gerdesi Brandt, 2002) is synonymised with the genus Macrostylis. Based on type material additional remarks and additions to the original descriptions are provided for both species. Results lead to following nomenclatorial changes: M. obscurus (Brandt, 1992), comb. n. and M. gerdesi (Brandt, 2002), comb. n. A setal nomenclature is proposed and the diagnosis for the family is revised.