Phylogenetic studies of the Madagascan freshwater crabs (Potamoidea, Potamonautidae, Deckeniinae)

Relationships within the Madagascan freshwater crab fauna were examined based on unstudied specimens from all parts of Madagascar. This study allowed the examination of the validity of existing genera and species, and identified potential new taxa. The new specimens provided phylogenetic and evolutionary data, as well as new insights into the distribution patterns of the Malagasy freshwater crab fauna. In addition, the large number of new localities from previously unsurveyed areas of Madagascar allowed the construction of updated distribution maps. The present analysis included 62 unidentified specimens plus 13 identified species of Malagasy freshwater crab taxa that had already been sequenced. The gene targeted for constructing the phylogeny was a partial mitochondrial gene fragment (600 bp), cytochrome oxidase I (COI). Phylogenetic analyses, MP, ML, and BI, yielded 36 most parsimonious trees and recovered topologies with several highly-supported clades with similar topologies. The MP 50% majority-rule strict consensus tree was selected as the representative topology. Results indicate that the unidentified and identified Malagasy freshwater crab specimens included in this study show a great deal of diversification that falls into nine well-supported clades (Clades 1-9). The distribution maps presented here based on comprehensive data from 500 identified individuals, 74 of which represent new localities, establish that freshwater crabs are found throughout all six provinces, and in all five ecoregions on the island. This includes new records from Mahajanga and Toliara Provinces. Improved taxonomic sampling for this study supports the validity of the current taxonomic assignment of seven of the eight currently recognized genera based on morphological and molecular studie