Sternotrigon Skopin

Ba, Yi-Bin & Ren, Guo-Dong, 2013, Taxonomy and distribution of Sternotrigon Skopin in China (Coleoptera, Tenebrionidae), Zootaxa 3693 (4), pp. 568-578 : 569

Key to the Chinese species of Sternotrigon Skopin

1. Mesosternum evenly arched longitudinally; never hump-like, hunched, or conically produced forward (Fig. 6, 19, 32, 71)... 2

- Mesosternum hump-like, hunched, often conically produced forward (Fig. 45)..................................... 7

2. Elytral humeri entirely visible in dorsal view; humeral rows clear, granules significantly coarser than in the humeri........ 3

- Elytral humeri not, or only partially visible in dorsal view, granules similar as in the humeri; mesosternum approximately flat; protibiae strong, knife-edge of outer margin jagged; the 3rd and 4th segments of antennae with densely long setae on apex in the male; length 17.0– 20.5 mm ........................................................................ S. zichyi

3. Elytra without or with inconspicuous 1st and 2nd ribs; prosternal process short, apex somewhat curved................... 4

- Elytral 1st and 2nd ribs obvious; prosternal process long, apex vertical; elytra shortly oval, lateral margins rather strongly rounded, shoulder entirely flat round, humeral rows inconspicuously rib-shaped; under margin of femora finely and sparsely granuliferous; length 18.0 mm..................................................................... S. hiekiei

4. Elytra without wrinkles or punctures, with obvious setae, small granules uniform and becoming faint towards elytral suture; humeri with finely granules; pseudoepipleuron sparsely covered in fine granules, the granules often faint; prosternal process short; ventral margins of femora with sparsely fine granules....................................................6

- Elytra with irregular wrinkles, often with vestiges of longitudinal ribs, without obvious setae, granules crassitude; humeri with larger granules; pseudoepipleuron densely covered in larger granules; prosternal process long; ventral margins of femora with dense flat larger tubers................................................................................. 5

5. Body with obvious white setae in dorsal view; labrum conversely trapezoidal; anterior margin of clypeus straight; 3rd antennomere 5.7 times as long as broad; apex of prosternal process without border, and thick in lateral view; length of protibial spurs approximately equal to basal two segments of tarsi; length 19.0– 22.5 mm ................................. S. albipulis

- Body without obviously white setae in dorsal view; labrum approximately square; anterior margin of clypeus concave; 3rd antennomere 4.0 times as long as broad; apex of prosternal process with thick border, and thin in lateral view; length of protibial spurs approximately equal to basal four segments of tarsi; length 17.0–19.0 mm.......................... S. grandis

6. Disc of pronotum weakly arched in lateral view; the granules of elytral rows erect and dense; outer margins of protibiae jagged only at apex (Fig. 30); pseudoepipleuron without setae; length 15.0–20.0 mm............................... S. kraatzi

- Disc of pronotum strongly arched in lateral view; the granules of elytral rows sparse; outer margins of protibiae jagged along nearly entire length; pseudoepipleuron with dense short setae; length 18.0 mm............................... S. opaca

7. Humera of elytra strongly acute, extended forward in dorsal view; disc of pronotum nearly flat medially; prosternal process strongly extended backward; length 17.0–19.0 mm............................................... S. setosa setosa

- Humera of elytra obsolete in dorsal view; disc of pronotum slightly arched medially; prosternal process shorter, usually curved; length 17.0–19.0mm................................................................ S. setosa juvencus