Morphogeographic variations in the genusEmphasis Type="Italic"Mesopodopsis/Emphasis Czerniavsky with descriptions of three new species (Crustacea, Mysidacea)

Most of the exceptional morphological features of the genusMesopodopsis are shared withNanomysis, Diamysis, andLimnomysis in a mosaic-like pattern. This group, comprising euryhaline species from fresh-to metahaline waters, has its centre of recent species richness in the Mediterranean to Ponto-Caspian region.Within the genus one may distinguish two morphogeographic groups, Euro-African species with a spine below the statocyst, and Indo-Australasian species without this spine. Detailed study from the entire distribution range indicates thatM. slabberi (van Beneden) should be split into 4 species: the nominal form from the NE-Atlantic, Mediterranean, and Black Sea, with 5–8 segments on the tarsus of the fourth thoracic endopod;M. aegyptia n.sp., widely distributed in the Mediterranean, with 7–9 segments on this tarsus as well as dimorphic setation patterns on the eighth tarsus;M. tropicalis n.sp. from equatorial W-Africa with 5–6 segments and dimorphic setation patterns on the mandibular palp; andM. wooldridgei n.sp. from South African waters with 9–12 segments on the tarsal joint of the fourth thoracic appendage, respectively.A key to the seven known species of the genus is given.