A new species of Potoroxyuris (Nematoda: Oxyuridae) from the woylie Bettongia penicillata (Marsupialia: Potoroidae) from southwestern Australia.

Potoroxyuris keninupensis n.sp. (Nematoda: Oxyuridae) is described based on specimens recovered from the caecum and colon of two woylies, Bettongia penicillata (Marsupialia: Potoroidae) from Western Australia. Only one other species of Potoroxyuris has been described previously, Potoroxyuris potoroo (Johnston and Mawson, 1939) Mawson, 1964, from Potorous tridactylus. The new species is most easily differentiated from P. potoroo by the shape of the pharyngeal lobes. The pharyngeal lobes of P. keninupensis n. sp. are widest at the base while those of P. potoroo are widest at the tip. The genus Potoroxyuris most closely resembles Macropoxyuris based especially on structures of the caudal end of males. The other three genera of oxyurids known to infect Australian marsupials have longer caudal alae, and more caudal papillae than these two genera. The genus Potoroxyuris has previously been defined by the characteristic that the pharyngeal lobes protrude through the oral opening. However, the pharyngeal lobes of P. keninupensis n. sp. do not quite protrude, so the definition of the genus should be modified as follows. The genus Potoroxyuris can be easily differentiated from Macropoxyuris by the following differences in the morphology of the buccal cavity. The pharyngeal lobes of Potoroxyuris almost reach the oral opening, or protrude beyond it, whereas those of Macropoxyuris only reach to about the anterior third of the buccal cavity. The buccal cavity of Potoroxyuris is poorly cuticularized compared to Macropoxyuris and other genera of oxyurids known from Australian marsupials, and does not contain inter-radial lamellae.