Morphometric divergence among populations of Rhinonicteris aurantius (Chiroptera : Hipposideridae) in northern Australia

Abstract

The isolation of the Pilbara population of the orange leaf-nosed bat, Rhinonicteris aurantius, from the Kimberley and the Northern Territory populations by the Great Sandy Desert, and the differences in climate and landscape between these regions, prompted a study of morphological divergence. Skull, noseleaf, ear and wing characters were used in a morphometric analysis of museum specimens. Univariate and multivariate analyses revealed subtle differences in the size of some snout and noseleaf measurements (condylocanine length, nasal breadth, rostral height, anterior leaf height and total noseleaf width) between the Pilbara and the northern populations, with smaller measurements in Pilbara animals. The species was otherwise morphologically conserved. Size differences may be indicative of a functional relationship with echolocation call frequency. Sexual dimorphism was identified in some skull measurements only (larger in males). Further study might confirm the subtle differences detected here in the snout and noseleaf and provide a functional basis for them. The isolation of R. aurantius in the Pilbara is part of a general pattern of allopatry, evolution and endemism in north-western Australia that resulted from the formation of the Great Sandy Desert.