Gastrointestinal Nematodes in the Lizard Genera Tiliqua and Cyclodomorphus (Scincidae) in Western-Australia

Nine species of nematode were recovered from the gastrointestinal tract of 82 lizards in the genus Tiliqua and 41 lizards in the genus Cyclodomorphus (Scincidae) in Western Australia. Parapharyngodon fitzroyi, sp. nov. possesses lateral alae in males and a prominent postanal cone bearing two very small papillae. There is no sclerotised V-shaped accessory piece, and the spicular pouch opens immediately posterior to the anus. The female's tail is rounded with a small slightly posteriorly-directed terminal spike. This nematode possesses some characteristics of Thelandros, and it is suggested that the taxonomic criteria differentiating these two genera have yet to be clarified. P. fitzroyi occurred at low prevalence and generally low intensity in Tiliqua multifasciata and Cyclodomorphus branchialis in the centre and north of the State. Thelandros trachysauri exhibited morphological variability, with two spicule lengths in males, and a wide range in tail lengths in the female. This species predominated at high intensity in Tiliqua rugosa in the south ana west, and Pharyngodon tiliquae occurred at high intensity and prevalence in Tiliqua occipitalis.,Tiliqua multifasciata and Cyclodomorphus branchialis throughout the State. Despite extensive sympatry between two pairs of these oxyurid species, and a limited area of sympatry between all three, these nematodes did not occur concurrently in the same individual to any significant extent. Abbreviata antarctica occurred at high prevalence and intensity in T. occipitalis in the south and west of the State. Encysted physalopterid larvae were only seen in the stomachs of T. multifasciata, in central and northern areas. Other species recorded were Abbreviata tumidocapitis (larva only), Kreisiella lesueurii, Pseudorictularia disparilis, Physalopteroides filicauda and Maxvachonia brygooi. Differences in the nematode communities in these four lizard species can be related to host diet, geographical range of host and of nematode (possible environmental constraints on the free-living stages), and perhaps inherent insusceptibility to infection.