Genus Onthophilus Leach
Key to the Korean species of the genus Onthophilus
1 (2) Body small, 1.82 2.34 mm. Third pronotal costa complete, not divided. Third elytral costa extending entirely to the front margin of the elytron. ........................................................ O. flavicornis Lewis, 1879
2 (1) Body large, 3.60 4.68 mm. Third pronotal costa (middle costa) divided into anterior and posterior parts, and well developed. Basal end of third elytral costa just caudad of a deep transverse fossa. ............................... O. ostreatus Lewis, 1879
Key to the Japanese species of the genus Onthophilus.
1( 2) Pronotum with 8 costae. Body length 2.50 - 2.65 mm. ............................................................................ O. silvae Lewis, 1884
2( 1) Pronotum with 4 or 6 costae.
3( 8) EC3 (elytral costa 3) ending just caudad of a deep transverse fossa situated within the front margin of the elytron.
4( 5) PC3 (pronotal costa 3) present on apical and basal half of the pronotum, and strongly developed. Body length, 3.60 - 4.68 mm. ...................................... O. ostreatus Lewis, 1879
5( 4) PC3 absent, or present only on basal half of the pronotum.
6( 7) PC3 present. Body length, 2.50 - 3.02 mm. ........................... O. niponensis Lewis, 1907
7( 6) PC3 absent. Body length, 3.28 - 3.38 mm. ............................................................... O. aonoi M. Ôhara et Nakane, 1986
8( 3) EC3 entire upto the front margin of elytron.
9(10) Body longer than 2.5 mm (2.86 - 3.54) mm. Elytral costae sometimes interrupted. .................................................... O. ordinarius Lewis, 1879
10( 9) Body shorter than 2.5 mm. Elytral costae clear and complete.
11(12) Propygidium with 3 costae. Body length, 1.82 - 2.34 mm. ............................................................... O. flavicornis Lewis, 1884
12(11) Propygidium with 1 costa. Body length 2 mm (after Adachi,
1930). ............................................. O. kamiyai
Adachi, 1930
Key to the Chinese species of the genus Onthophilus.
1 Pronotum costae indistinct, almost absent. ........... O. smetanai Mazur
1' Pronotum with distinct costae. .......................................................... 2
2 Pronotum with 8 costae. .................................. O. silvae Lewis, 1884
2' Pronotum with 6 costae. ...................................................................... 3
3 Elytral costae interrupted, forming elongate tubercles. .................. O. liijiangensis Zhou et Luo, 2001
3' Elytral costae not interrupted to form elongate tubercles. ..................... 4
4 Elytral fossa between EC2 and EC 4 reduced, elytral costae narrow. ............ O. ordinarius Lewis
4' Elytral fossa between EC2 and EC4 deep, well-developed. .................. 5
5 Elytral fossa transverse and much deeper; the basal part of EC2 and EC4 prominent, costae on pronotum developed and higher. ........................ O. ostreatus Lewis
5' Elytral costae narrower, not so prominent, pronotal costae reduced. ......... O. foveipennis Lewis