The present paper describes Mnementh brennei n. sp. n. gen., a new non-marine ostracod species and genus from temporary wetlands in the Western Cape Province (South Africa). The new genus is the fifth in the subfamily Cypridinae and a phylogenetic analysis using morphological characters demonstrates that it is most closely related to its putative sister taxon Pseudocypris. Apart from this cluster, the phylogenies are not at all robust and this is to all probability due to the incongruent (mosaic) evolution amongst the different characters in valve and soft part modules. Implications of such incongruent evolution of characters for the concept of genera in this group are discussed. © 2007 Taylor & Francis.