A New Symmorphic Sibling Species of Drosophila (Diptera) from the Island of Maui, Hawaii

Drosophila affinidisjuncta Hardy n. sp. (Diptera) is morphologically indistinguishable from its sibling D. disjuncta Hardy and is described as a new species based upon genetic differences. By cytogenetic and cross-mating studies it has been demonstrated that populations of Drosophila, which have been previously treated as disjuncta Hardy ( 1965:245) , from the mountains of West Maui repre- sent a biologically distinct species. Drosophila disjuncta appears to be restricted to the slopes of Haleakala, East Maui. Specimens from East and West Maui are indistinguishable morphologically, but the chromo- somes show a number of fixed differences, and cross-mating experi- ments demonstrate that hybrid males are sterile. The species are char- acterized by the following chromosomal differences; D. disjuncta has a metaphase karyotype consisting of five pairs of rod-shaped and one pair of dot-like chromosomes. In contrast, the metaphase karyotype of D. affinidisjuncta shows three pairs of large, V-shaped chromosomes, one pair of large and one pair of small J-shaped chromosomes and a pair of dot-like chromosomes. This difference between the karyotypes of the species is due to the presence of large heterochromatic blocks on each of the autosomes as well as on the X chromosome. Further de- tails are presented in this journal in the following article, "Cytogenetic