Key to genera of the tribe Opsiini from Arabian Peninsula (based on males)

(Modified from Emeljanov 1964; Knight, 1970; Zahniser & Dietrich, 2008 and Wu et al., 2010)

1. Mesal margin of eye notched; aedeagus with one apically bifurcated shaft......................................... 2

- Mesal margin of eye entire; shafts of aedeagus separated throughout their extent.................................... 3

2. (1) Crown convex, narrowly rounded to face; pygofer without appendage............................. Neoaliturus Distant

- Crown concave, distinctly angularly curved to face; pygofer with appendage........................ Concavifer Dlabola

3. (1’) Forewing with dark brown border to medial spot of approximately constant width.................................. 4

- Forewing without dark brown spots........................................................................ 5

4. (3) Aedeagus with shafts directed posteriorly at base and curving dorsally; atrium not extending ventrad of shafts.................................................................................................. Hishimonus Ishihara

- Aedeagus with shafts directed ventroposteriorly at base and curving dorsally; atrium extending ventrad of shafts.................................................................................................... Naevus Knight

5. (3’) Aedeagus without basal process, branches arising separately from socle......................................... 6

- Aedeagus with pair of ventral basal processes arising from socle............................................... 8

6. (5) Vertex, pronotum and scutellum with distinctive irregular red markings; forewing with scattered small dark brown spots.......................................................................................... Masiripius Dlabola

- Vertex, pronotum, scutellum and forewing with dark-brown vermiculate lines...................................... 7

7. (6’) Aedeagus with parallel or diverging or slightly converging branches, apices of branches narrowly produced, neither reflexed nor hooked............................................................................... Orosius Distant (Aedeagus with apices of branches with hooked process in Pacific distributed genus Nesophrosyne (Kirkaldy))

- Aedeagus with diverging branches bent inwards at mid-length, apices of branches distinctively curved or reflexed to form dis- tinctive tips........................................................................... Paraorosius gen. n.

8. (5’) Anterior margin of head rounded, never with carina or ridge.......................................... Opsius Fieber

- Anterior margin of head sharply angulate, with distinct transverse carina.......................... Phlepsopsius Dlabola