Ceruchus

Huang, Hao, Imura, Yûki & Chen, Chang-Chin, 2011, Notes on the genus Ceruchus MacLeay from China, with the description of a new species (Coleoptera: Scarabaeoidea: Lucanidae), Zootaxa 2906, pp. 1-42 : 12-13

Key to male Ceruchus from the Palaearctic region

The males can be easily distinguished from the females for all the known species by the presence of dorsal tooth and an isolated basal mola on mandible. Ceruchus chuduraziensis from Myanmar is not included because it was poorly described and not examined by the authors, so some important characters remain unknown. Ceruchus chrysomelinus , Ceruchus atavus , and Ceruchus reginae have been fully redescribed by Boucher & Kral (1997) and are included.

1 Pronotum with lateral margins strongly convex. Anterior margin of pronotum markedly wider than posterior margin of head.................................................................................. Ceruchus luojishanensis

- Pronotum with lateral margins nearly straight or weakly convex. Anterior margin of pronotum slightly wider than posterior margin of head........................................................................................ 2

2 Yellow setae on inner apex of the mesotibia forming a brush of long setae ( Fig. 46 )................................. 3

- Yellow setae on inner apex of the mesotibia short or obsolete, at most forming a brush of short setae ( Figs. 47–53 )........ 7

3 Yellow setae on posterior half of the mesofemur sparse and short, neither denser nor longer than the setae on anterior half of the mesofemur.......................................................................... Ceruchus atavus

- Yellow setae on posterior half of the mesofemur denser and longer than the setae on anterior half of the mesofemur....... 4

4 Central split on the caudal margin of the basal piece of the aedeagus in ventral view entirely absent. Dorsal tooth of the mandible separated from base of the mandible (for larger-sized specimens). Ventral tooth of the mandible in lateral view protruding and pointed. Depressed longitudinal striations on the elytra shallow and thin................... Ceruchus chrysomelinus

- Central split on the caudal margin of the basal piece of the aedeagus in ventral view more or less present. Dorsal tooth of the mandible close to the base of the mandible (for larger-sized specimens). Ventral tooth of the mandible in lateral view inconspicuous or absent. Depressed longitudinal striations on the elytra deep and wide................................... 5

5 Mentum wide and transverse, with lateral margins convergent posteriorly. Ventral tooth of the mandible entirely absent. Penis in ventral view wide. Lateral sides of the central split on the caudal margin of the basal piece of the aedeagus in ventral view protruding posteriorly, forming an m-shaped caudal margin....................................... Ceruchus reginae

- Mentum thin and less transverse, with lateral margins not convergent posteriorly. Ventral tooth of the mandible visible even in small-sized specimens. Penis in ventral view thin. Lateral sides of the central split on the caudal margin of the basal piece of the aedeagus in ventral view flat or oblique but not protruding posteriorly........................................ 6

6 Penis longer and protruding well beyond the parameres in natural shape. Central split on the caudal margin of the basal piece of the aedeagus in ventral view deep and V-shaped.............................................. Ceruchus deuvei

- Penis shorter and not protruding well beyond the parameres in natural shape. Central split on the caudal margin of the basal piece of the aedeagus in ventral view minute or obsolete, not V-shaped............................ Ceruchus katerinae

7 Dorsal tooth of the mandible in dorsal view stout, very broad at base, with a longer anterior margin, and close to basal tooth of the mandible. Central split on the caudal margin of the basal piece of the aedeagus in ventral view broad and deep, forming a large V-shaped gap between bases of the parameres. Endophallus wide and long, nearly as long as penis … Ceruchus lignarius

- Dorsal tooth of the mandible in dorsal view slender, narrow at base, with a shorter anterior margin, and separated from basal tooth of the mandible. Central split on the caudal margin of the basal piece of the aedeagus in ventral view narrow or minute, at most forming a small gap. Endophallus narrow and short, not markedly longer than half of penis..................... 8

8 Yellow setae on the inner apex of the mesotibia sparse, not forming a brush. Inner sclerite near the dorsal margin of the paramere well developed................................................................... Ceruchus yangi

- Yellow setae on the inner apex of the mesotibia dense, more or less forming a narrow brush. Inner sclerite near the dorsal margin of the paramere reduced or obsolete................................................................... 9

9 Dorsal surface of penis in lateral view markedly incurved at cephalic part, with wings along the margins.... Ceruchus minor

- Dorsal surface of penis in lateral view slightly incurved, without wings along the margins........................... 10

10 Anterior margin of the mentum noticeably protruding medially. Depressed longitudinal striations on the elytra deep. Two sides of central split on the caudal margin of the basal piece of the aedeagus in ventral view protruding posteriorly, forming an mshaped margin. Penis in ventral view thinner, and markedly swollen in middle......................... Ceruchus niger

- Anterior margin of the mentum slightly convex, not protruding medially. Depressed longitudinal striations on the elytra shallow. Two sides of central split on the caudal margin of the basal piece of the aedeagus in ventral view flat and not protruding posteriorly, not forming an m-shaped margin. Penis in ventral view wider, not swollen in middle..................... 11

11 Ventral tooth of the mandible visible. Mentum less transverse..................................... Ceruchus sinensis

- Ventral tooth of the mandible entirely absent. Mentum more transverse.............................. Ceruchus tabanai

Figures

FIGURES 46 – 53. Mesofemur and mesotibia in ventral view. 46 — Ceruchus katerinae; 47 — Ceruchus lignarius monticola; 48 — Ceruchus minor; 49 — Ceruchus niger; 50 — Ceruchus sinensis; 51 — Ceruchus yangi; 52 — Ceruchus luojishanensis; 53 — Ceruchus tabanai.