Parathelandros allisoni n. sp. from the intestines of the frog Nyctimystes trachydermis (Hylidae) from Central Province, Papua New Guinea is described and illustrated. It is the 12th species assigned to the genus and the ninth species of Parathelandros to be reported from the Australo-Papuan region. Parathelandros allisoni n. sp. is most similar to Parathelandros australiensis in that the vulva occurs near the esophageal bulb, but differs in that males lack the spherical postcloacal lobe characteristic of P. australiensis. The description of P. andersoni is amended to include operculate eggs and rosette papillae on the tail of the male.