A revision of the freshwater crab genus Adeleana Bott, 1969 from Borneo and Sumatra (Decapoda: Brachyura: Gecarcinucidae), with descriptions of two new genera and two new species

The freshwater gecarcinucid crab genus Adeleana Bott, 1969 was originally established for A. forcarti Bott, 1969 from Sabah, East Malaysia, Borneo, and comprises three other species from Sumatra and Borneo. One species, A. kenepai (De Man, 1899), was transferred to Bakousa Ng, 1995 by Ng (1995) but the status of the others has remained uncertain. The taxonomy of the genus is revised using a suite of characters, and Adeleana Bott, 1969 is restricted for the type species A. forcarti. Adeleana chapmani Holthuis, 1979, obtained from caves in northern Sarawak, East Malaysia, Borneo, is referred to a new genus, Niahusan. gen., and a new species is also described from central Borneo, Indonesia. Adeleana sumatrensis (Balss, 1934) from Sumatra, Indonesia, is placed in a new genus, Samudrasan. gen., and a new species is described from the northern part of the island.