Taxonomic research is of fundamental importance in conservation management of threatened species, providing an understanding of species diversity on which management plans are based. The grassland earless dragon lizards (Agamidae: Tympanocryptis ) of southeastern Australia have long been of conservation concern but there have been ongoing taxonomic uncertainties. We provide a comprehensive taxonomic review of this group, integrating multiple lines of evidence, including phylogeography (mtDNA), phylogenomics (SNPs), external morphology and micro X-ray CT scans. Based on these data we assign the lectotype of T. lineata to the Canberra region, restrict the distribution of T. pinguicolla to Victoria and name two new species: T. osbornei sp. nov. (Cooma) and T. mccartneyi sp. nov. (Bathurst). Our results have significant conservation implications. Of particular concern is T. pinguicolla , with the last confident sighting in 1969, raising the possibility of the first extinction of a reptile on mainland Australia. However, our results are equivocal as to whether T. pinguicolla is extant or extinct, emphasizing the immediate imperative for continued surveys to locate any remaining populations of T. pinguicolla . We also highlight the need for a full revision of conservation management plans for all the grassland earless dragons.
Lord Howe Island (LHI) is a remote oceanic island in the south-west Pacific that is World Heritage listed due to its diverse, and largely endemic, biota. A suite of introduced species have colonised the island, resulting in the widespread population declines of many native species. The delicate skink (Lampropholis delicata DeVis) was accidentally introduced to LHI from mainland eastern Australia, but there has been no detailed investigation of its biology on the island, or its potential impact on the native biota. We conducted a detailed study of the distribution and biology of the delicate skink on LHI over a six-year period (2007–12). The delicate skink was introduced to LHI in the 1980s, and rapidly spread across the island. It presently occurs in all 21 low-elevation vegetation communities on LHI. The delicate skink is diurnal on LHI, and displays seasonal variation in activity with a peak in November–December. The delicate skink exhibits sexual dimorphism with females having larger body and abdomen sizes and males having longer and broader heads, although the degree of genetic admixture may influence morphology on LHI. Females reproduce in spring and summer (September–February), with a positive relationship between body size and clutch size. Clutch size ranges from 1 to 7 (mean 3.4) and communal egg nests (11–200+ eggs) are common. Tail loss is common on LHI (55%), but is more frequent in adults and females. We conclude that, based on its distribution and abundance, the delicate skink has the potential to impact the diverse and endemic invertebrate fauna on LHI.
Morphologically cryptic taxa have proved to be a long-standing challenge for taxonomists. Lineages that show strong genomic structuring across the landscape but are phenotypically similar pose a conundrum, with traditional morphological analyses of these cryptic lineages struggling to keep up with species delimitation advances. Micro X-ray computed tomography (CT) combined with geometric morphometric analyses provides a promising avenue for identification of morphologically cryptic taxa, given its ability to detect subtle differences in anatomical structures. However, this approach has yet to be used in combination with genomic data in a comparative analytical framework to distinguish cryptic taxa. We present an integrative approach incorporating genomic and geometric morphometric evidence to assess the species delimitation of grassland earless dragons (Tympanocryptis spp.) in north-eastern Australia. Using mitochondrial and nuclear genes (ND2 and RAG1, respectively), along with $>$8500 SNPs (nuclear single nucleotide polymorphisms), we assess the evolutionary independence of target lineages and several closely related species. We then integrate phylogenomic data with osteological cranial variation between lineages using landmark-based analyses of three-dimensional CT models. High levels of genomic differentiation between the three target lineages were uncovered, also supported by significant osteological differences. By incorporating multiple lines of evidence, we provide strong support for three undescribed cryptic lineages of Tympanocryptis in north-eastern Australia that warrant taxonomic review. Our approach demonstrates the successful application of CT with integrative taxonomic approaches for cryptic species delimitation, which is broadly applicable across vertebrates containing morphologically similar yet genetically distinct lineages. Additionally, we provide a review of recent integrative taxonomic approaches for cryptic species delimitation and an assessment of how our approach can value-add to taxonomic research.
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