New species of Mesamphisopus, an endemic South African freshwater isopod genus (Isopoda: Phreatoicidea: Mesamphisopidae)

Abstract

Isopoda of the suborder Phreatoicidea are represented in Africa by a single genus, Mesamphisopus, including four known species (M. abbreviatus, M. capensis, M. depressus and M. penicillatus). Six new species are described here, i.e. Mesamphisopus albidus n. sp., M. baccatus n. sp., M. kensleyi n. sp., M. paludosus n. sp., M. setosus n. sp., and M. tsitsikamma n. sp. These taxa are distinguished from each other and from the existing species using a combination of features of the antennae, mouthparts, pleopods, pleotelson and uropods, and by colouration and setation. The distinguishing features and presumed affinities of the species are presented and discussed. A dichotomous key to the species of the genus is also provided. With recent cladistic analyses suggesting that re-arrangements are necessary at the familial level, the removal of Eophreatoicus resulting in a monotypic Mesamphisopidae is considered.