Historical notes on various collectors of unidentified freshwater crabs (Crustacea: Decapoda: Brachyura) from the Malay Peninsula and Borneo, with descriptions of two new species of Isolapotamon Bott, 1968 (Potamidae)

Several lots of unidentified crabs assigned to Potamidae, Gecarcinucidae, and Sesarmidae from the Malay Peninsula and Northern Borneo were examined from material deposited in the reference collections of the Natural History Museum, London. While most of the species have been reported elsewhere, there are some new locality records, and surprisingly, two undescribed species of Isolapotamon Bott, 1968, a relatively well-studied Bornean-Philippine endemic potamid genus. These freshwater crabs are documented, the new taxa described, and notes are provided on the various collectors associated with this material, some of which date to the late 1800s.