Two new species of Neosarmatium, N. papuense n. sp. and N. bidentatum n. sp., are described from mangrove environments in the Timika region, Papua, Indonesia. Neosarmatium papuense n. sp. is characterized by the presence of two chitinous teeth, and one non-chitinous tooth, closely set proximally on the dorsal surface of the dactyl of the cheliped. The closest species is N. trispinosum Davie, 1994, which has three chitinous teeth on the dorsal surface of the dactyl of the cheliped. Neosarmatium bidentatum n. sp. differs from other species by having only two dorsal teeth on the proximal quarter of the dactyl of the cheliped as well as differences in abdomen and carapace proportions.
Crustacea, Decapoda, Grapsoidea, Sesarmidae, Neosarmatium, mangrove, Papua, Indonesia, Western Pacific, new species.