Krefftascaris (Nematoda, Ascaridoidea) from Australian side-necked turtles with description of krefftascaris sharpiloi SP. N. from chelodina rugosa

Previously known records of ascaridoid nematodes Krefftascaris Sprent, 1980 are summarized and new records of the genus reported. Krefftascaris sharpiloi Tkach, Kuzmin et Snyder, sp. n. is described from specimens found in the stomach of the northern snake-necked turtle Chelodina rugosa collected from two localities in Northern Territory, Australia. The new species differs from the only previously known Krefftascaris species, K. parmenteri Sprent, 1980, by the presence of thickened and bifurcated anterior edges of the lateral cuticular alae and a difference in the relative distance from the anterior end to the nerve ring which is 1.5 to 2 times greater in K. parmenteri. Comparison of approximately 2.100 bases of ribosomal DNA sequences This study contains first reports of Krefftascaris in Chelodina rugosa, Chelodina burrungandjii, Chelodina canni and Emydura tanybaraga and the first records of this genus in the Northern Territory, Queensland and Western Australia. Molecular phylogenetic analysis based on sequences of nuclear small ribosomal subunit gene has demonstrated close affinities between Krefftascaris and Heterocheilus, the type genus of the Heterocheilidae and Heterocheilinae. Parasitism of several species and genera of Heterocheilidae in crocodiles allows us to hypothesize that Krefftascaris may have been acquired by turtles from crocodilians.