The Chromosomes of Six Species of the Drosophila lativittata Complex

Abstract

Metaphase and polytene karyotypes were investigated in six Australian species of the Drosophila (Scaptodrosophila) coracina species-group: lativittata, enigma, specensis, howensis, nitidithorax and novamaculosa. The male metaphase karyotype of each species consists of three pairs of telocentric; one pair of metacentric and one pair of small heterochromatic chromosomes, plus a large acrocentric X-chromosome and a smaller acrocentric Y-chromosome. The polytene karyotype of each species consists of six arms and a small chromocentre. No inversion polymorphisms were found in the two species (lativittata and enigma) investigated for this phenomenon. Interspecific crosses obtained between enigma and howensis and between lativittata and nitidithorax revealed that the former species (between which sexual isolation is incomplete) are entirely homosequential, and differences in polytene banding patterns between the latter species are very slight. Photographic comparisons otherwise revealed that the banding sequences of all six species are substantially identical.