The East Asian millipede genus Riukiupeltis Verhoeff, 1939 is revised, and is restricted to a single species, R. jamashinai Verhoeff, 1939. Examination of the type specimens and freshly collected material from the Ryukyu Archipelago and Vietnam show that both subsequently allocated species, Riukiupeltis uenoi Murakami, 1975, and R. falcatus (originally Haplogonosoma falcatum Attems, 1953, reallocated by Jeekel 1968), do not belong to this genus; moreover, they are not even congeneric with each other. According to our morphological observations, including the gonopods, R. uenoi is closer to the widespread Chamberlinius hualienensis Wang, 1956, hence we propose the new combination Ch. uenoi (Murakami, 1975), comb. n. Riukiupeltis falcatus, on the other hand, represents a separate, as yet monotypic, genus Simplogonomorpha gen. n., distinct both from Haplogonosoma Brölemann, 1916 sensu Golovatch et al. (1995), and from Verhoeff’s original Riukiupeltis. Additionally, Simplogonomorpha falcata (Attems, 1953), comb. n is re-described here based on fresh material from Vietnam. A key and colour habitus-illustrations to all three species are also provided here.
