Key to female Ceruchus from China and Japan

Ceruchus chrysomelinus, Ceruchus atavus, and Ceruchus chuduraziensis from outside China have not been examined by the authors and the information from the literature is scant, therefore the following key only includes species from China and Japan. Ceruchus reginae is not included as the female is unknown.

1 Transversal carina on pronotum obsolete, not conspicuous. Inner mola of mandible without central tooth. Stylus nearly three times as long as wide................................................................... Ceruchus lignarius

- Transversal carina on pronotum conspicuous. Inner mola of mandible with one or two clear, central teeth. Stylus less than three times as long as wide.................................................................................. 2

2 Mola of mandible with single, central tooth. Width/length ratio of the pronotum less than 1.7. Lateral margins of the pronotum weakly convex........................................................................................ 3

- Mola of mandible with double, central teeth. Width/length ratio of the pronotum greater than 1.8. Lateral margins of the prono- tum strongly convex................................................................ Ceruchus luojishanensis

3 Flattened marginal area of the pronotum relatively wide. Stylus nearly twice as long as wide............. Ceruchus minor

- Flattened marginal area of the pronotum relatively narrow. Stylus nearly as long as wide............................. 4

4 Pronotum with a pair of lateral protuberances outside of the transversal carina..................................... 5

- Pronotum without a pair of lateral protuberances outside of the transversal carina...................... Ceruchus deuvei

5 Sclerotized part of the hemisternite with inner lateral margin shorter than distal margin of hemisternite................. 6

- Sclerotized part of the hemisternite with inner lateral margin at least as long as distal margin of hemisternite............ 7

6 Entrance of the spermatheca sclerotized. Spermathecal duct relatively long. Stylus with outer lateral corner weakly protruding..................................................................................... Ceruchus katerinae

- Entrance of the spermatheca not sclerotized. Spermathecal duct relatively short. Stylus with outer lateral corner noticeably pro- truding.................................................................................. Ceruchus yangi

7 Elytra with deep striations................................................................... Ceruchus niger

- Elytra with shallow striations............................................. Ceruchus sinensis & Ceruchus tabanai