Systematics of the snake-eyed skinks, Genus Cryptoblepharus Wiegmann (Squamata: Scinidae)

  • Paul George Horner

    Student thesis: Doctor of Philosophy (PhD) - CDU


    A systematic study of the genus Cryptoblepharus Wiegmann (Reptilia: Scincidae) is presented which combines a revision with a limited phylogenetic analysis. Included are assessments of alpha taxonomy, geographic variation and biogeography.

    Morphologically conservative, Cryptoblepharus was once treated as a single polytypic species comprising many geographical subspecies and was considered the world’s most broadly distributed lizard. The study is population based and concentrates on taxa from the Australian region.

    Initially, 12 morphologically distinctive Australian populations were recognised and their genetic relationships investigated by allozyme electrophoresis, which identified discrete Operational Taxonomic Units (OTUs). Variation at 45 loci was screened in 401 individuals from 176 localities resulting in the identification of two genetic lineages, 29 OTUs and two zones of hybridisation. Morphological variation of the genetically identified OTUs was investigated by pairwise comparisons of 21 meristic and 12 mensural variables, the results of which allowed a further 528 individuals to be assigned to OTUs on the basis of morphological similarity. Analysis of the increased data set (920 individuals) by stepwise discriminant function analysis and pairwise comparisons resulted in the identification of 24 Australian taxa.

    Using discriminating morphological variables identified by the comparative Australian analyses, species boundaries of taxa extralimital to Australia were also investigated, resulting in the recognition of 13 taxa from the southwest Indian Ocean region and 22 from the Indo-Pacific region. Overall, Cryptoblepharus was determined to comprise 59 taxa, consisting of 43 monotypic and seven polytypic species. Existing types were able to be assigned to 42 taxa and 17 taxa are described as new.

    A phylogenetic analysis of Australian species-level taxa was performed using 15 meristic and 11 mensural characters coded using Thiele’s gap-weighting method. The resulting phylogeny was deemed biased by convergence and inadequate to resolve relationships. A hypothesis for the biogeography of the genus suggests that it originated in South-east Asia and achieved its present distribution by a combination of rafting and human mediated transport. Accounts of each Australian taxon include synonymy, diagnosis, description of external morphology and colour pattern, reproductive biology, distribution, list of sympatric congeners, geographic variation, comparison with other taxa, natural history and etymology.

    Accounts of extralimital taxa are based on small sample sizes and are less detailed, giving a description, distribution and brief remark section. Dichotomous keys to the identification of taxa from each geographic region are provided.
    Date of AwardOct 2006
    Original languageEnglish
    SupervisorCharles Webb (Supervisor) & Keith Christian (Supervisor)

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