A new species of the genus Spiroxys (Nematoda; Spiruroidea) from Australian chelonians of the genus Chelodina (Chelidae)

Summary Spiroxys chelodinae n. sp. is described from Australia in three species of freshwater chelonian, Chelodina longicollis, C. expansa and C. oblonga and from New Guinea in an unidentified freshwater chelonian. S. chelodinae differs from other species of the genus in having pseudolabia each with a blunt, prominent, cuticular projection (tooth) on the middle lobe and no other cuticular prominences, a cuticular collar without spines or protrusions, and a gubernaculum with tubes through which the spicules pass. Larvae (probably fourth-stage larvae of S. chelodinae) are also described. This is the first record of a Spiroxys sp. from the Australian Region, and from a host group (suborder Pleurodira), which has a Gondwana distribution. This is discussed in relation to the zoogeography of the genus Spiroxys and it is postulated that Australian chelids acquired this parasite from non-marine cryptodires (possibly carettochelyids or trionychids). In addition, a Spiroxys sp. is recorded from Nigeria, constituting the first such record from the Ethiopian Region. It was found in Pelusius subniger, thus constituting the second record of a Spiroxys species in a pleurodire.