Key to males of species of Culicoides (Marksomyia)

1. Wing cell M4 with single pale spot (fig 52, 56).............................................................. 2

- Wing cell M4 with two pale spots (fig 51, 53–55)............................................................ 3

2. Shoulders of aedeagus of similar thickness to basal arms (fig 50); parameres separate throughout (fig 50)............. dycei

- Shoulders of aedeagus distinctly thicker than basal arms (fig 46); parameres weakly joined near base (fig 46)................................................................................................... pseudostigmaticus

3. In genitalia, membrane of ninth sternite not spiculate medially, ventral root of gonocoxite not developed (fig 45, 47)...... 4

- In genitalia, membrane of ninth sternite spiculate medially, ventral root of gonocoxite well developed (fig 48, 49)......... 5

4. Parameres curved laterad almost at 90° apically, medially with triangular excavation (fig 47), proximal pale spot in M4 ovoid to triangular (fig 53)............................................................................... zentae

- Parameres angular and bent maximally at 45° apically, medially entire (fig 45), proximal spot in M4 usually boomerang shaped (fig 51)................................................................................... marksi

5. Basal arms of parameres rounded, roughly parallel or converging apically, meeting body of paramere along basal edge at an angle close to 90° (fig 49).................................................................. parvimaculatus

- Basal arms of parameres almost straight, divergent apically, meeting body of paramere along basal edge at an angle of about 135° (fig 48)...................................................................................... kayi