Key to the genera of Tomarus (sensu lato)

1 Frons concave at middle. Clypeal teeth widely separated (about 4 tooth diameters) (Fig. 1A). Metasternum glabrous on anterior corners. Male with protarsomere 4 subquadrate, with a lateral striate projection at apex (Fig. 10A), and inner claw bifid (Fig. 10B). Internal sac with long brush of setae (Fig. 21A)...................................... Euligyrus Casey, 1915

- Frons flat at middle. Clypeal tooth not or widely separated (about 1–3 tooth diameters). Metasternum with minute to long setae on anterior corners. Male with protarsomere 4 subcylindrical to subrectangular, without projections, rarely with a ventral striate projection at apex, and inner claw simple or truncate with a mall acute projection. Internal sac without long brush of setae.. 2

2 Head with conical to transverse tubercles (Fig. 1H–K). Mandible with outer lateral tooth narrowly rounded to nearly absent (Fig. 5F–H). Maxilla with teeth 3 and 4 in parallel position (Fig. 3F). Metasternum with minute to short, sparse setae. Metafemur without well-defined anterior row of punctures. Metepisternum short to very short (2.3–3.0 times longer than wide). Apex of tergite IV with a wide stridulatory area of 13–20 parallel lines of tubercles. Prosternal process flat, without dorsal setae. Pygidium of male with transverse thin rugosity at base (Fig. 9F–L). Internal sac with complex of spine-like accessory lamellae (Figs. 22–23)...................................................................... Tomarus Erichson, 1847

- Head with carina or tumescences. Mandible with outer lateral tooth widely rounded to acute, well developed. Maxilla with teeth 3 and 4 in diagonal position (Fig. 3E, G), or tooth 4 absent (Fig. 3H). Metasternum with long to very long, dense setae. Metafemur with well-defined, sometimes double, anterior row of punctures. Metepisternum long to very long (3.2–3.9 times longer than wide). Apex of tergite IV with a diagonal narrow strip of carinae or a wide stridulatory area of 6 striae. Prosternal process convex, with dorsal setae; if flat and glabrous, then divided by a deep transverse sulcus. Pygidium of male with minute to large punctures, rarely rugopunctate. Internal sac without complex of spine-like accessory lamellae.................. 3

3 Apical margins of mesotibia dentate (Fig. 12B). Antennal club short (1.1–1.3 times as long as antennomeres 2–7). Mentum subquadrate (as long as wide) (Fig. 2F). Pronotum with apical marginal bead incomplete on middle 1/5. Surface of pronotum, elytra, and pygidium with large, dense punctures. Metepisternum glabrous.Apex of tergite IV with a wide stridulatory area of 6, thin striae (Fig. 8A). Sternite VIII of female narrowly emarginate. Internal sac without copulatory lamella and without lamellar spiny belt; with complex of comma-like accessory lamellae (Fig. 21B). Spiculum gastrale T-shaped (Fig. 14B)..................................................................................................... Proculigyrus

- Apical margin of mesotibia entire to crenulate (Fig. 12C–F). Antennal club long to very long (1.5–2 times as long as antennomeres 2–7). Mentum triangular to subrectangular (longer than wide) (Fig. 2A–E). Pronotum with apical marginal bead complete. Surface of pronotum, elytra, and pygidium variable. Metepisternum with long setae. Apex of tergite IV with a narrow stridulatory area consisting of a diagonal strip of short, transverse, parallel carinae (Fig. 8B–C). Sternite VIII of female entire. Internal sac with copulatory lamella and with lamellar spiny belt; with simple accessory lamella (Fig. 12C–E). Spiculum gastrale Y-shaped (Fig. 14D)........................................................... Ligyrus Burmeister, 1847