The Rediscovery of Angel's Stream Snake, Paratapinophis praemaxillaris Angel, 1929 (Reptilia: Serpentes: Natricidae)

Paratapinophis praemaxillaris was described by Angel (1929) on the basis of two neonate specimens from Xieng-Khouang in northern Laos. Pope later placed the genus in the synonymy of Opisthotropis Günther, 1872. We collected five adult specimens along the Nan River, in northern Thailand. Here we describe the adults of Angel's Stream Snake, discuss the monotypic genus, its distribution, habitat, and diet. Based upon morphology we remove Paratapinophis Angel, 1929 from the synomomy of Opisthotropis. An identification matrix is provided for identifying snakes in the genera Opsithotropis, Parahelicops, and Paratapinophis Bourret, 1934, all have been considered Opisthotropis at one time or another, and we comment on the status of Opisthotropis.