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Evolutionary, molecular and comparative zoology
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RESEARCH ARTICLE
Contents Vol 58(2)

Dwarf monitor lizards (Varanidae : Varanus, Odatria s. gen.) as definitive and paratenic hosts for physalopteran nematodes

Hugh I. Jones
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Discipline of Microbiology and Immunology, M502, University of Western Australia, Nedlands, WA 6009, Australia. Email: hjones@cyllene.uwa.edu.au

Australian Journal of Zoology 58(2) 69-75 https://doi.org/10.1071/ZO09122
Submitted: 24 December 2009  Accepted: 17 March 2010   Published: 20 May 2010

Abstract

Nematodes in the genus Abbreviata (Physalopteridae) were the dominant gastrointestinal helminths in the eight smallest species of dwarf varanid lizards (subgenus Odatria, Varanidae). All host species supported infection with encysted physalopterid larvae, which provoked minimal pathological changes in the host. The mean number of cysts in host tissues increased with host size across species. There were moderate prevalences of infection of adult A. hastaspicula in Varanus (O.) brevicauda (50%) and V. (O.) storri (32%), and of A. levicauda in V. (O.) pilbarensis (46%). There were no adult Abbreviata sp. infections in V. (O.) bushi. Intensity of infection was low in almost all hosts. Sympatric larger species of Varanus (subgenus Varanus) (V. gouldii, V. panoptes, and V. (O.) tristis) support heavy infections of these nematodes which may be a source of infection for dwarf varanids. The presence and species of adult Abbreviata in dwarf monitors could not be related to sympatry, host size, or host geographical range. Liability to infection is probably determined by a combination of phylogeny (in A. levicauda in V. pilbarensis and V. tristis, dwarfism being derived), and habitat (A. levicauda occurring in other arboreal species). Other facets of the physiology or ecology, not yet understood, are also probably involved. This study reveals a complex situation where evolutionary history and contemporary environments interact. Physalopteroides filicauda, Maxvachonia brygooi, Wanaristrongylus ctenoti, Hastospiculum gouldi, the cestode Oochoristica vacuolata, and a species of pentastomid were also recovered in low numbers.


Acknowledgements

I thank Brad Maryan of the Western Australian Museum for allowing me access to specimens and working space, and for providing collection data, to Ms Slavica Pervan, School of Surgery and Pathology, University of Western Australia, for histological preparations, and Russ Hobbs, School of Veterinary Studies, Murdoch University, for assistance with statistics, and for critically reading an earlier draft of this paper.


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