Intraspecific Variation in the Vocalizations and Hand Pad Morphology of Southern Lesser Bush Babies (Galago moholi): A Comparison with G. senegalensis

Abstract

Previous studies have shown the taxonomic value of vocal repertoires and hand (volar) pad characteristics in the classification of cryptic nocturnal primates such as bush babies. However, no study included quantitative comparisons within the geographical range of any one species. We investigated levels of intraspecific variation in calls and hand pad characteristics of the southern lesser bush baby (Galago moholi), using the northern lesser bush baby (Galago senegalensis) for interspecific comparisons. Examination of calls recorded from different regions along a transect of 1500 km across southern Africa revealed low levels of intraspecific variation in Galago moholi, whereas comparisons with homologous call-types in G. senegalensis revealed them to be significantly different. Volar pad measurements across the ranges of both species also showed low levels of intraspecific variation and relatively high interspecific variation. These findings demonstrate that vocal and volar pad characteristics can be used as consistent measures of difference between species that look almost identical. These methods provide a practical means of distinguishing between cryptic species, whether in the field, in captivity, or, in the case of volar pads, of preserved specimens.