Cytogenetical aspects of morsitans tsetse flies with particular reference to Glossina pallidipes (Diptera, Glossinidae)

The basic diploid chromosome of Glossina pallidipes is 2n = 6 and includes a pair of large sub-metacentric autosomes (L1), a shorter pair of metacentric autosomes (L2), and an X and Y which constitute a heteromorphic pair. The male meiotic sequence, although similar to that of other tsetse species, is characterized by asynapsis between X and Y chromosomes, and only tenuous association between the autosomes. Giemsa C-banding characteristics are described for the chromosomes of five species/sub-species and by means of this technique a whole range of hitherto unsuspected polymorphisms have been discovered. Polytene chromosome maps of G. pallidipes have been prepared and a description of all principal cytological markers is provided. A detailed comparison between these chromosomes and those of G. austeni has been conducted, and the conclusion is that although they must share a common ancestor, extensive band differences and structural change have occurred during phylogeny.