Key to species of Orphnus from Sri Lanka (males)

1. Pronotum with more or less developed tubercle on base medially (Figs 1A–B, 2A–C, 3A–C). Endophallus with 1 group of spinules (Figs 1G, 3G) ....................................................................... 2

– Pronotum without tubercle on base medially (Figs 4A, H, 5A, H). Endophallus with more than 1 distinct group of spinules (Figs 4D, 5D) .......................................................................................... 3

2. Larger: body length 8.0–10.0 mm. Spinules of endophallus as a rather dispersed group of more than 10 spinules (Fig. 1G). Tubercle on base of pronotum normally with 2 punctures; punctures may be close to each other or indistinct in some specimens ............. Orphnus mysoriensis Westwood, 1845

– Smaller: body length 4.6–6.0 mm. Spinules of endophallus in a compact cluster consisting of less than 10 spinules (Fig. 3G). Tubercle on base of pronotum smooth ...... Orphnus medvedevi sp. nov.

3. Parameres in dorsal view with small but distinct notches basad of lateral teeth (Fig. 4F). Parameres longer, about 0.7 length of phallobase (Fig. 4E). Abdominal sternite 8 medially longer than sternites 4–7 combined ............................................................................... Orphnus bicolor (Fabricius, 1801)

– Parameres in dorsal view without notches basad of lateral teeth (Fig. 5G). Parameres shorter, about 0.5 length of phallobase (Fig. 5F). Abdominal sternite 8 medially as long as sternites 4–7 combined .................................................................................. Orphnus parvus (Wiedemann, 1823)