Notes on the identification of Uperoleia Gray, 1841 toadlets from the Darwin region of the Northern Territory, with comments on the ecology, detection, and conservation management of the Vulnerable Howard River Toadlet (U. daviesae)

WA Museum Records and Supplements | Updated 7 months ago

ABSTRACT – Three species of Uperoleia toadlets occur in the Darwin region, and are difficult to tell apart due to similar size and colouration. Identification has generally relied on differences in male advertisement calls. Uperoleia daviesae is the Northern Territory’s only threatened frog and is impacted by urban development and sand mining. Given their threatened status and significance in development impact assessments, having a method of species identification that does not rely on calling males is particularly important. Here we outline a reliable and simple method for the morphological identification of each of the three species based on the shape, size and placement of the parotoid and inguinal glands. We also provide comments on the ecology and habitat of U. daviesae, and key information on detectability to improve survey work on this threatened species. We broadly characterise U. daviesae sites as ‘persistent flowing’ or ‘intermittent flowing’ based on our observations of surface water flow and calling patterns. Persistent sites have surface flow and support U. daviesae calling for weeks or months after the first significant rainfall, whereas intermittent sites may require 10-day cumulative rainfall totals of >100 mm to trigger calling which may persist for a few days only. Detectability of U. daviesae from calling is therefore site specific. Effective conservation planning and species recovery would be aided by research into U. daviesae population dynamics, hydrology of sandsheet heath habitats and the potential for sand mining rehabilitation.