A new species of Mysidium (Peracarida: Mysida: Mysidae) from the eastern tropical Pacific

A new species of Mysidium from the eastern tropical Pacific, Mexico, is described, representing the second species of this genus described for the Pacific Ocean and the eighth species reported worldwide. Mysidium pumae sp. nov. is distinguished from the other species of the genus by several characters including: the lanceolate appendix masculina, 3× as long as wide, tapering distally, with a distal tuft of 16 setae and an inner proximal tuft of more than 30 setae, the male pleopod 4 with endopod bearing 3 setae, the exopod with 4 articles, the modified seta from article 3 of the exopod bifid, telson 2.3× as long as wide, distally concave. A table with the main differences among all the known species in the genus is provided.