Karyotypic differences in two sibling species of Scotophilus from South Africa (Vespertilionidae, Chiroptera, Mammalia)

Abstract

Karyotype descriptions are given for Scotophilus dinganii (2n = 36, FNa = 50) and a recently discovered sister-species, Scotophilus sp. nov. (2n = 36, FNa = 52). These two sibling species occur sympatrically and are distinguished by body size, echolocation frequency and cytochrome b sequence. Cytogenetically, both species differ from other Scotophilus species in the subtelocentric morphology of chromosome 2 and a terminal heterochromatic segment on the X chromosome. Further, Scotophilus sp. nov. is characterized by a subtelocentric chromosome 4 not found in any other Scotophilus species. Comparing the Scotophilus karyotype with that of the vespertilionid genus Myotis, extensive conservation of whole chromosome arms has been found recently. However, out of 25 chromosomal arms six could not be identified in Scotophilus. Therefore, in the present study fluorescence in situ hybridization with whole chromosome painting probes from Myotis myotis was carried out on metaphase preparations from Scotophilus dinganii and Scotophilus sp. nov. These experiments revealed that three previously unidentified Scotophilus chromosomes (A, B, C) contain homologous sequences to Myotis chromosomes 18 plus 22, 19 plus 25, and 16/17, respectively.