Orthogonius, Macleay, 1825

Tian, Ming-yi & Deuve, Thierry, 2007, A Taxonomic Treatment Of The Species Of Orthogonius Macleay (Coleoptera: Carabidae: Orthogoniini) Of Singapore, Raffles Bulletin of Zoology 55 (2), pp. 261-266 : 265

Key to species of Orthogonius of Singapore

1. Clypeus quadrisetose ........................................................................ 2

– Clypeus bisetose ............................................................................... 4

2. Body rather flat and broad, reddish-brown, large (Length 20.0–21.0 mm) ............................................................................. O. hopei Gray

– Body more convex and slender, dark brown, medium sized ...... 3

3. Elytral striae shallow, intervals flat. Length 14.0 mm .................... ....................................................................... O. saundersi Andrewes

– Elytral striae deep, intervals convex. Length 14.5 mm ................... ................................................................... O. thaicus Tian & Deuve

4. Ligula with glossal sclerite quadrisetose at apex, mentum with a median tooth, hind angle of pronotum angular ............................ 5

– Glossal sclerite bisetose at apex, mentum without median tooth, hind angle of pronotum rounded .................................................... 6

5. Head impunctate, labrum straight at front, interval 6 of elytra impunctate near base, smaller. Length 13.5–14 mm ....................... ........................................................ O. singaporensis Tian & Deuve

– Head sparsely punctate on vertex, labrum slightly emarginate at front, interval 6 of elytra with a few punctures near base, larger. Length 16.0– 17.5 mm ....................... O. fairmairei Tian & Deuve

6. Head punctate, interval 7 of elytra more or less carinate ............ 7

– Head impunctate, interval 7 of elytra not carinate ....................... 9

7. Head densely punctate, pronotum impunctate .............................. 8

– Head and pronotum sparsely punctate. Length 12.0 mm .............. ........................................................... O. solidicornis Tian & Deuve

8. Labrum straight at front,the elytral base obscurely bordered,aedeagus stout. Length 15.0 mm ..................... O. emarginatus , new species

– Labrum slightly convex at front, the elytral base unbordered against intervals 1–3, and aedeagus slender in), and aedeagus stouter.Length 13.0 mm ...................................... O. andrewesianus Tian & Deuve

9. Elytral striae shallow, intervals slightly convex, impunctate. Length 13.5–14.0 mm .................................. O. dongnanya Tian & Deuve

– Elytral striae deep, intervals moderately convex; intervals 3, 5, 6 and 8 sparsely punctate, punctures small. Length 10.5 mm .......... .............................................................. O. cyclothorax , new species