Lethrus (Sinolethrus) serpentifer Semenov & Medvedev, 1935 (Figs. 3–4, 13–14, 17, 55, 57, 59–64) Lethrus (Heteroplistodes) serpentifer Semenov & Medvedev 1935: 286 (original description, type locality: “Mongoliae ora australis, Nan-Shanj, Tshshuniche”); Semenov & Medvedev 1936: 89 (key, distribution, iconography: Tab. II Figs. 54, Tab. V Fig. 115, Tab. VII Fig. 176, Tab. IX Fig. 225, Tab. XI Fig. 282). Lethrus (Autolethrus) serpentifer: Nikolajev 1968: 531 (taxonomic note, key). Lethrus (Ceratodirus) serpentifer: Nikolajev & Puntsagdulam 1984: 110 (key, characteristic, distribution); Nikolajev 2003: 93 (key, characteristic, distribution, iconography: Figs. 62 Nr. 1–2); Král & Nikolajev 2006: 92 (catalogue); Nikolajev et al. 2016: 48 (catalogue); Bagaturov & Nikolajev 2015: 309 (note, distribution); Schoolmeesters 2021 (online catalogue). Lethrus (Subgen.?) serpentifer: Baraud 1992: 81 (key, taxonomic note). Lethrus serpentifer: Krajčík 2012: 142 (catalogue). Type material examined. Syntype, Ô (ZMAS) “ДОЛ[ина] Р[еки] ЧхунихƐ/ 12 IV 09 ƐкЗ[емпЛЯР] КОЗЛОва [hw] // Heteroplistodus / serpentifer / sp. n. Ô [hw] / A. Semenov-Tian-Shansky det. [p] 22 [hw] // Holotypus [p] // St. Petersburg / Zool. Inst [p]”. Additional material examined (7 specimens). China c., Monan, river Huang He (34°07'N / 111°07'E) [Henan], 26–28. V. 1996, leg. J. Halada, Ô (ZSM, ex. coll. O. Hillert), Ô (NMPC) [first records from Henan province, China]; Kansu [Gansu], Tu-kiang [35°25'N 103°47'E], ♀ (ZSM, ex. coll. O. Hillert); China - Gansu, Dingxi [35°34'N 104°36'E], 7.8.– 12.8.1996, E. Kučera leg., Ô ♀ (NMPC, ex. coll. D. Král) [first records from Gansu province, China]; China, Sechuan, Wenchuan [31°24'N, 103°34'E], 18.6. – 19.6.2001, leg. E. Kučera, ♀ (ZSM,) [first record from Sichuan province, China]; China, centr. Shanxi, Chao Shan, 37°06'N 112°24'E, 25km SE Pingyao 4. – 5.VII.2001, Jaroslav Turna leg., Ô (NMPC, ex. coll. D. Král) [first record from Shanxi province, China]. Redescription (based on the male from Monan). Body length 16.0 mm. Dorsal surface black, without any metallic lustre or shiny parts (probably present in freshly collected specimens). Head (Figs. 13–14, 17, 58–64). Labrum bilobed, asymmetrical, right lobe slightly more developed; surface rugosely, shallowly and sparsely punctate; anterior margin with dense row of long macrosetae. Clypeus transverse, nearly semicircular. Eye canthus exceeding eyes distinctly, projecting anterolaterad, indistinctly semicircular, interrupted, anterolateral angle angular, oblique keel above eyes absent. Pleurostomal process evenly rounded, not exceeding ventrolateral mandibular outline. Punctation of clypeus, frons and occiput similarly impressed, consisting of distinct but weakly regularly distanced punctures, intermixed with fine and also regularly distributed ones; eye canthus distinctly rugose. Mentum strongly convex in lateral aspect (Fig. 61, 64), with distinct concavity basally, shortly and densely setaceous. Mandibles with asymmetrical mandibular appendices, left being long, angled nearly 90° downward and from half of length bending regularly forward in lateral aspect (serpent like), s-shaped in frontal aspect; right appendix only weakly developed, visibly as a weakly elevation. Exterior mandibular outline straight from base to apex in dorsal aspect (Figs. 13–14, 17, 58–59, 61–64), with maximum width approximately at base. Length of mandibles distinctly less than length of head, dorsal surface of right mandible absent from any elevations or protuberance, dorsal surface of left mandible with weakly arcuate protuberance at middle of length, shortly anteriorly of labrum, directed to the side of right mandible. Apex of both mandibles absent of subapical protuberances. Pronotum transverse, equal as base of elytra, broadest just posteriorly of middle (Fig. 58); margin entirely bordered, slightly crenulate. Anterior angles with evenly rounded outline. Punctation of dorsal surface simple, distinct, weakly irregular, punctures separated by one diameter, intermixed with fine simple punctuation. Scutellum (Fig. 58) widely triangular, strong shagreened. Elytra (Fig. 58) almost semicircular, apices not prominent, apex of each elytron forming dependent arcus, with indistinct striae, with broad, distinct shagreened intervals. Epipleuron strongly narrowed apicad, epipleural keel reaching elytron apex. Legs. Profemur not armed, protibia with eight gradually diminishing external denticles proximad, and with row of shallow tubercles on ventromedial edge. Apical spur of protibia without subbasal process, weakly s-shaped (Fig. 55). Aedeagus as in Figs. 3–4. Females differ from males as follows: body broader, ventral mandibular appendices absent; hornlike dorsal protuberans of mandibular surface absent, apical spur of protibia simple and straight (Fig. 60). Distribution. China (Gansu, Henan, Qinghai, Shanxi and Sichuan provinces) (Fig. 65).

Published as part of Bagaturov, Mikhail F. & Hillert, Oliver, 2023, Sinolethrus, a new subgenus of the genus Lethrus Scopoli, 1777 from China (Coleoptera: Geotrupidae: Lethrinae) and new synonymy of the subgenus Paralethrus Nikolajev, 2003, pp. 301-316 in Zootaxa 5258 (3) on page 304, DOI: 10.11646/zootaxa.5258.3.4, http://zenodo.org/record/7780393