Molecular phylogenetics and biogeography of the Old World true freshwater crabs, with emphasis on the fauna of Sri Lanka

Abstract

With about 6,800 species described , the Brachyura or true crabs are the most species-rich group of Decapoda, such as lobsters, crabs and shrimp (Ng et al. 2008; De Grave et al. 2009). An astonishing one fifth ("'1280 species) of those crabs are true freshwater Gecarcinucoidea, Potamoidea, (Cumberlidge et al., 2008). crabs, belonging Pseudothelphusoidea to four superfamilies: and Trichodactyloidea During the past twenty years, freshwater crab taxonomy and systematics have undergone major changes, with many new species described. Diagnostic morphological characters are re-weighted at all levels (from superfamily to species). The scant fossil record and the unresolved marine sister group(s) and ancestors hamper the reconstruction of freshwater crab relationships. The growth of molecular tools is of great importance for evolutionary biology, including freshwater crab evolutionary history. In this study, I use molecular tools to elucidate the phylogeny of the Old World true freshwater crabs, and address other evolutionary questions that pertain to past biogeographical events and with Sri Lanka in particular, questions concerning biodiversity and conservation issues.