A cladistic analysis of Platythelphusa A. Milne-Edwards, 1887, from Lake Tanganyika, East Africa (Decapoda: Potamoidea: Platythelphusidae) with comments on the phylogenetic position of the group

The phylogenetic relationships of the freshwater crab genus Platythelphusa were investigated by means of a cladistic analysis using morphological characters. The platythelphusa were found to be a monophyletic assemblage, this finding supports the recognition of the family Platythelphusidae. Platythelphusa is endemic to Lake Tanganyika, East Africa, and some of its species bear a striking resemblance to certain marine crabs (grapsids). The study does not support the idea that the Platythelphusidae emerged from a relict population of a grapsid or grapsid-like taxon: the evidence supports an hypothesis for the evolution of this family from freshwater crab ancestors. Parsimony considerations position the freshwater crab family Deckeniidae as the sister group of the platythelphusids. In addition, the Palaeotropical freshwater crabs appear to constitute a monophyletic group.