Chromosomes of Lemuriformes. V. A comparison of the karyotypes of Cheirogaleus medius and Lemur fulvus fulvus.

In this report we compare the karyotype of Lemus fulvus fulvus (2n=60) with that of Cheirogaleus medius (2n=66), a species thought to retain the ancestral lemur karyotype. A culture technique was designed specifically for lemur lymphocytes to facilitate description of the complete karyotypes using G--banding, C-banding, and Ag-AS staining for nucleolus organizer regions (NOR's). Different G-banding patterns in three chromosome pairs and different NOR-bearing chromosomes between the two species, as well as additional chromosomes and interstitial C-bands in C. medius, suggest that the chromosome complement of C. medius may not perfectly reflect the ancestral morphology. However, allowing for a Robertsonian centric fusion and a pericentric inversion, the G-banding patterns of 27 of the 32 autosomal pairs of C. medius are indistinguishable from those of L. fulvus fulvus. This constitutes strong justification for assigning these chromosomes to the ancestral lemur karyotype.