Notes on hemipenial morphology and its phylogenetic implications in the Pygopodidae Boulenger, 1884

The Pygopodidae is a near-endemic Australian family of limb-reduced, imbricately scaled gekkotans, currently comprising 44 species (43 in Australia, 2 in New Guinea). Phylogenetic studies of the Pygopodidae have enlisted molecular, morphometric, and osteological methods to resolve intergeneric and interspecific relationships, however, only one publication details the morphology of pygopodid hemipenes, providing data on four species from three genera. Here, we augment these initial observations, by describing hemipenial condition in an additional 19 species across four genera, bringing current totals to 23 pygopodid species across five of seven recognized genera. Focused sampling of the genus Delma allows us to identify species groups based on hemipenial shape and ornamentation, and general morphology of cloacal spurs. We identify the presence of a single-lobed hemipenis in both Aprasia and Delma, and hypothesize this modification in reproductive anatomy has occurred twice independently in pygopodid evolution.