Drosophila subobscura

Drosophila subobscura is a species of fruit fly in the family Drosophilidae. Originally found around the Mediterranean, it has spread to most of Europe and the Near East. It has been introduced into the west coasts of Canada, the United States, and Chile. Its closest relative is Drosophila madeirensis, found in the Madeira Islands, followed by D. guanche, found in the Canary Islands. These three species form the D. subobscura species subgroup. When they mate, males and females perform an elaborate courtship dance, in which the female can either turn away to end the mating ritual, or stick out her proboscis in response to the male's, allowing copulation to proceed. D. subobscura has been regarded as a model organism for its use in evolutionary-biological studies. Both wild type and laboratory-reared individuals of D. subobscura are brown, with clear wings, yellow halters, yellowish legs, and red eyes. They do not exhibit sexual size dimorphism; the males and females are about 2 mm (0.08 in) long. The males have a brown antenna, grey pollinose, and brown dorsal surface of the thorax. The tergum (dorsal area excluding the head) is dark brown. There are three tarsal segments on the fore legs. The first segment is the longest and contains the proximal comb, which has 7-12 teeth. The second segment contains the distal comb, which has 10-13 teeth. The females share the same characteristics as the males, except in respect to tarsal combs. The eggs are only half the length of those of the closely related D. obscura species. Its larvae and pupa are of the usual drosophilid type. The arista (bristles arising from the antennae) of D. subobscura contain 6-8 branches, with 1-2 of those branches below the terminal fork. The species has a brown antenna with grey pollinosity that is approximately the same color as the rest of the head-capsule. The front of the antenna is dark brown and matte, without any pollinosity except on the frontal triangle and fronto-orbital plates, both of which are shiny and slightly pollinose.