Maxillary shape as a diagnostic tool for identifying fruit bats, Epomophorus crypturus and E. wahlbergi from museum specimens and in the field.

Two species of common, co-occurring southern African fruit bats, Epomophorus wahlbergi and E. crypturus,are difficult to distinguish in the field. The main character used to distinguish them is the arrangement of palatal ridges (two behind last molar in E. crypturus, one in E. wahlbergi); this character is difficult to see in the field and unreliable in juvenile skulls. Many workers have commented on the more slender and elongated shape of the muzzle of E. crypturus compared with E. wahlbergi. We test the usefulness of this character by comparing skull length and maxillary length and width in 51 skulls in museum collections representing both species. Our data revealed broad overlap in skull length between species (reflected in overall body size overlap),but (after allowing for age-related variation) complete separation of the sexes by maxillary length (males >21.5 mm; females <21.5 mm) and skull length (males >52 mm; females <52 mm) and complete separation of species by maxillary width ( E. wahlbergi >13 mm for females and >14 mm for males; E. crypturus <13 mm for females and <14 mm for males). We discuss field characters that may permit species diagnosis based on maxilla shape, as well as acoustic characters. [ABSTRACT FROM AUTHOR]