A revision of the Madagascan freshwater crab genus Hydrothelphusa A. Milne-Edwards, 1872 (Brachyura, Deckeniidae, Hydrothelphusinae), with a new species of this genus from northern Madagascar

Abstract The Madagascan freshwater crab genus Hydrothelphusa is revised and a new species of this genus from northern Madagascar is described. A revised identification key to distinguish among the species now assigned to Hydrothelphusa is provided. The new species, H. christophamon n. sp. is recognized based on a combination of morphological characters and previous molecular data and is illustrated here. The addition of the new species to Hydrothelphusa brings the number of species in this genus to four, with the others being H. agilis , H. madagascariensis and H. bombetokensis , that are all endemic to Madagascar.