Differentiation in cranial variables among six species of Hylopetes (Sciurinae：Pteromyini)

There is some discrepancy in the classification of different species of Hylopetes, particularly regarding systematic status of H. electilis and H. phayrei and their relationship to other species. In the present study, for the first time we have brought together six of the nine Hylopetes speciesand performed statistical analysis of 14 measurable cranial variables, analyzing in total 89 specimens, including H. electilis, H. alboniger, H. phayrei, H. lepidus, H. spadiceus, and H. nigripes. Both univariate and multivariate analysis results indicate that H. electilis can not only be obviously distinguished from H. phayrei, but also clearly differs from the other four Hylopetes species. These results sustain the contention that H. electilis is neither a synonym nor subspecies of H. phayrei,but should be considered a distinct and valid species. Subsequently, a straightforward discussion on the biogeography of Hylopetes in southeastern Asia gives further insight into the differentiation and variety of species belonging to this genus.