Relative brain size and morphology of some South African bats

Measures of relative brain size and brain macromorphology are described for four species of Microchiroptera, two from the Vespertilionidae and two from the Rhinolophidae, and two species from the Pteropodidae (Megachiroptera). Four brain parameters (brain length, hemisphere length, brain width and brain height) were measured, and converted to indices of proportion to allow interspecific comparison. The megachiropteran species have relatively larger brains than the microchiropteran species, this being primarily a result of the greater development of the cerebral hemispheres in the former group. Of the microchiropteran species, Miniopterus schreibersii has the highest value for comparative brain size and its brain shows several characteristics of the more encephalized Megachiroptera such as reduced exposure of the mesencephalic tectum, and the presence of prominent cerebral sulci. The possibility that the differences in brain size and development between the Megachiroptera and the Microchiroptera, may be related to diet, or that they may be of phylogenetic origin, is discussed.