The meiotic and mitotic chromosomes of picture-winged Hawaiian Drosophila species. I. Drosophila grimshawi and D. cyrtoloma.

The mitotic and meiotic chromosomes of Drosophila grimshawi and Drosophila cyrtoloma, species of the picture-wing group of Hawaiian Drosophilidae, are described. The "primitive" Drosophila karyotype of five pairs of rods and one pair of dots, found in grimshawi, is compared with the karyotype for cyrtoloma, which consists of five pairs of V-shaped and one pair of J-shaped chromosomes. Cytological material was prepared by an acetoorcein technique and by C-, G-, and N-banding methods. The rod-shaped chromosomes of grimshawi contained approximately 45% heterochromatin as determined by differential staining with Giemsa. Each chromosome of cyrtoloma consists of a euchromatic arm and a heterochromatic arm; the total heterochromatin of the diploid set averaged between 55 and 60%. These measurements approximate the amounts of satellite DNA reported for these two species. Prophase and metaphase figures from both meiotic and mitotic divisions are shown.