Subfamily Scarabaeinae Latreille, 1802

Scarabaeides Latreille, 1802, Hist. Nat. Gen. Part. Crust. Ins., 3: 144 (Type genus: Scarabaeus Linnaeus, 1758).

Description. Body size small to large (1.5–68.0 mm in length); body shape round to oval, mostly robust and convex, though some flattened; body colour black to brown, some with patchy colouration, a few with metallic sheen. Clypeus expanded and fused with the prominences on head, covering the mouthparts. Antenna has 8 or 9 segments, with antennal club consists of 3 segments. Pronotum broad, some with tubercles or carinae. Scutellum hidden in most genera. Elytron often with 7 or 8 striae. Pygidium exposed as a distinctive feature of this subfamily. Abdominal spiracles on pleural membrane, covered by elytra. Middle coxae widely separated. Sexual dimorphism common.

Remarks. Eleven tribes of Scarabaeinae were recorded worldwide, including 9 tribes from China and 7 tribes from Hong Kong.

Key to tribes of Scarabaeinae from Hong Kong.

1 Metafemurs strongly elongated, meso- and metatibiae slender, metatibiae often slightly curved, metatarsi weakly triangluar with the first segment slightly longer; body flat and broadly oval, sexual dimorphism exists but not easily observable................................... 2 Metafemurs short and strong, meso- and metatibiae short and strongly broaden anteriorly; for Onitini, protibiae without spur; metatarsi almost trianglular with the first segment obviously longer and stronger; body strongly convex in most cases, sexual dimorphism conspicuous......................................................................................................................................................................4

2 Mesocoxae slightly separated and oblique, sometimes very close; metasternum strongly narrow anteriorly; body mostly medium to large sized, broadly oval or narrow posteriorly ....................................................................................................................................3 Mesocoxae strongly separated and parallel; metasternum not strongly narrow anteriorly; body size small, rarely medium ................. .............................................................................................................................................................................................. Sisyphini

3 Medium to small sized; protarsi visible, all tarsi with two claws; anterior clypeal margin weakly toothed, sometimes obtuse; antennal club brown or dark brown; elytral base curved inward; scutellum not observable....................................................... Gymnopleurini Large sized; protarsi invisible, meso- and metatarsi short and small with one or two claw(s), but sometimes none; anterior clypeal margin strongly toothed; antennal club yellow; elytral base not curved inward; scutellum very small or not observable ..................... ...................................................................................................................................................................................... Scararabaeini

4 The second segment of labial palpus shorter than the first segment, the third segment always very long; sexual dimorphism conspicuous, head and pronotum with strong prominence, ridge or groove; elytra with one or two lateral carina(e)............... Coprini The second segment of labial palpus longer than the first segment, the third segment always very short, sometimes absent; sexual dimorphism exists, but not easily observable; elytra without lateral carina .........................................................................................5

5 Antanna has 8 segments; ventral side of pronotum without antennal groove; elytra flat .................................................... Oniticellini Antanna has 9 segments; ventral side of pronotum with antennal groove; elytra convex ....................................................................6

6 Pronotum with 2 depressions near the base; protarsi lacking in male or both genders; protibial spurs not movable, protibia often slender and curved in male; scutellum visible; body size medium, rarely large......................................................................... Onitini Pronotum without depression near the base; protarsi visible, protibial spurs movable, protibia not slender and curved; scutellum not observable; body size small, rarely medium .................................................................................................................. Onthophagini