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| Nephrurus eromanga Oliver, Donnellan & Gunn, 2022 DOI: 10.1071/ZO22008 |
Abstract
Across Australia’s monsoon tropics and vast arid zone isolated regions or ‘islands’ of upland or rocky habitat are home to disjunct populations of many taxa of plants and animals. Comparative analyses of lineages that occur across these habitat islands provide opportunities to understand when and how environmental change drove isolation and diversification across arid Australia. Here we present an analysis of mitochondrial genetic diversity across disjunct populations of geckos in the Nephrurus asper group. Dating analyses suggest that disjunct and genetically divergent populations spanning the northern half of Australia diverged through the Plio–Pleistocene. Based on the timing of divergence and current habitat associations we hypothesise that species in this lineage were isolated by the expansion of unsuitable arid-zone habitats from the late Pliocene onwards. Across most areas, these barriers appear to be sandy or stony deserts. However, in eastern Australia genetically divergent populations are separated by grassland on flat vertisol-dominated soils (‘blacksoils’), suggesting that these habitats also expanded during the late Pliocene aridification. Finally, we show that western Queensland populations formerly referred to N. asper are genetically divergent and diagnosable on the basis of colour pattern and, herein, recognise these populations as a distinct species.
Keywords: aridification, biogeography, blacksoil, Nephrurus eromanga sp. nov, refugia, sandy deserts, stony deserts, vicariance, gecko.
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| Photographs of examples of Nephrurus asper East and West showing variation in colour pattern in life: (a) (c) N. asper West from Cork Station; (d) N. asper East from Moura; (e) N. asper East from Almaden; and (f ) N. asper East from Hervey’s Range. Photographs: (a) Angus Emmott, (b) Queensland Museum, (c, d) Steve Wilson, (e, f ) Chris Jolly. |
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| Nephrurus eromanga (a) from West from Noonbah Station; (b) from West from South Galway Range Station. |
Nephrurus eromanga Oliver, Donnellan & Gunn, sp. nov.
(Eromanga Basin Knob-Tail Gecko)
Diagnosis: Nephrurus eromanga, sp. nov. can be distinguished from other taxa in the N. asper group by the following combination of characters: moderately large size (maximum SVL males ~105 mm, females ~114 mm); fawn to mid-brown (reddish in life) dorsal colouration on dorsal and lateral surfaces of head, torso and limbs; narrow to wide pale dorsal crossbands or broken series of blotches; dark-brown saddle on the nape, which extends posterior to the forelimbs and contrasts strongly with the base colouration on the back the head and remainder of torso; digits lacking dark-brown or grey bands or flecks; and basal scales surrounding each tubercle uniform in height and less than half the height of the scale they enclose.
Etymology: Named after the Eromanga Basin, a Mesozoic sedimentary basin in inland eastern Australia that entirely circumscribes the distribution of the species. The name Eromanga is in turn derived from the small town of Eromanga (at which this species does not occur). Eromanga is used as a noun in apposition.
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| habitat for Nephrurus eromanga, sp. nov. in western Queensland, Australia: (a) Beal Range, South Galway Station; The species is typically found associated with scree habitats on and around mesas. Photographs: (a) Steve Wilson |
Paul M. Oliver, Stephen C. Donnellan and Bee F. Gunn. 2022. Plio–Pleistocene Vicariance across Arid Australia in the ‘Spiny Knob-tailed Geckos’ (Nephrurus asper group), with the Description of A New Species from western Queensland. Australian Journal of Zoology. 69(6); 216-228. DOI: 10.1071/ZO22008
Understanding the diversity of some of Queensland’s oddest lizards
