Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera

Abstract

Revised definitions are given for the genus Mysidium Dana, 1852, and its eight previously known species, based on material from Curacao, Bonaire and SE-Brazil, along with the evaluation of published data. Type material of Diamysis columbiae Zimmer, 1915, M.\xa0cubanense Băcescu\xa0& Ortiz, 1984 and M.\xa0rubroculatum Băcescu\xa0& Ortiz, 1984 is examined. A lectotype is designated for D.\xa0columbiae Zimmer, 1915, a senior synonym of Mysidium columbiae (Zimmer, 1915). Two new species are described, M. triangulare Wittmann sp.\xa0nov. from Curacao and M. antillarum Wittmann sp.\xa0nov. from Curacao and Bonaire. Known ranges are extended by first records of M.\xa0cubanense from Curacao and Bonaire and of M.\xa0integrum W.M.\xa0Tattersall, 1951 from SE\xa0Brazil. Three morphologically different groups are established at the subgeneric level: (1) the nominotypical subgenus Mysidium Dana, 1852 with M.\xa0gracile (Dana, 1852), M.\xa0integrum , M.\xa0cubanense , M.\xa0rubroculatum and M.\xa0triangulare sp.\xa0nov. from the West Atlantic plus M.\xa0rickettsi Harrison\xa0& Bowman, 1987 from the East Pacific; (2) Occimysidium Wittmann subgen. nov. represented only by M.\xa0pumae Ortiz, Hendrickx\xa0& Winfield, 2017 from the Pacific coast of Mexico; and finally (3) Orientomysidium Wittmann subgen. nov. comprising M.\xa0columbiae and M.\xa0antillarum sp.\xa0nov. from the West Atlantic. The poorly known M.\xa0iliffei Băcescu, 1991 is not assigned to any subgenus. A key to the resulting three subgenera and ten nominal species of the genus Mysidium is given.