Three new species of freshwater crabs from northern Laos, with a note on Potamiscus (Ranguna) pealianoides Bott, 1966 (Crustacea, Decapoda, Brachyura, Potamidae)

Three new species of potamid crabs are described from northem Laos, viz., Potamon lao n. sp., Dromothelphusa prabang n. sp. and Thaiipotamon kittikooni n. sp. Potamon lao n. sp. is characterized by its squarish carapace, third maxilliped with an elongate rectangular ischium and a short but distinct flagellum on the exopod, and its stout male first pleopod (G1) with a weak dorsal flap on the terminal segment. The key distinguishing features of Dromothelphusa prabang n. sp. are its low epibranchial tooth, broadly triangular externat orbital angle and stout G1 terminal segment. Thaipotamon kittikooni n. sp. is readily distinguished from its congeners by its sharp, distinctly cristate anterolateral carapace margins and by the densely setose outer margin of the third maxilliped exopod. Potamon lao n. sp. and Dromothelphusa prabang n. sp. are close to Potamiscus (Ranguna) pealianoides Bott, 1966, which is here transferred to the genus Dromothelphusa Naiyanetr, 1992.