Definitions of two species groups of Stenothemus Bourgeois (Coleoptera, Cantharidae), with descriptions of three new species from China Author Ge, Shujuan 0000-0002-3621-5068 The Key Laboratory of Zoological Systematics and Application, School of Life Science, Institute of Life Science and Green Development, Hebei University, Baoding 071002, Hebei Province, China. Author Yang, Xingke 0000-0003-3676-6828 Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China. 20191685 @ stumail. hbu. edu. cn; https: // orcid. org / 0000 - 0002 - 3621 - 5068 & yangxk @ ioz. ac. cn; https: // orcid. org / 0000 - 0003 - 3676 - 6828 yangxk@ioz.ac.cn Author Liu, Haoyu 0000-0003-1383-5560 The Key Laboratory of Zoological Systematics and Application, School of Life Science, Institute of Life Science and Green Development, Hebei University, Baoding 071002, Hebei Province, China. & liuhy @ hbu. edu. cn; https: // orcid. org / 0000 - 0003 - 1383 - 5560 liuhy@hbu.edu.cn Author Yang, Yuxia 0000-0002-3118-6659 The Key Laboratory of Zoological Systematics and Application, School of Life Science, Institute of Life Science and Green Development, Hebei University, Baoding 071002, Hebei Province, China. & yxyang @ hbu. edu. cn; https: // orcid. org / 0000 - 0002 - 3118 - 6659 yxyang@hbu.edu.cn text Zootaxa 2021 2021-09-29 5047 2 139 152 journal article 10.11646/zootaxa.5047.2.3 1175-5326 5540628 0C398339-EF37-45C2-AA8C-3BDAF601E2AB Key to the species of Stenothemus Bourgeois 1. Female with abdominal tergite VIII curled ventrally on both sides ( Yang et al. , 2014 : figs 9‒10); male genitalia: ventral process of each paramere elongate and more or less expanded terminally, dorsal plate strongly narrowed apically, ventral process and dorsal plate bent ventrally together ( Yang et al. 2014 : figs 21‒41).......................... S. harmandi species-group - Female with abdominal tergite VIII normal, not as above; male genitalia: ventral process and dorsal plate of each paramere normal, not as above or hardly bent ventrally.............................................................. .. 2 2. Body stout, less than 4.0 × as long as wide; head width across eyes nearly as long as or narrower than anterior margin of pronotum in males; male genitalia: dorsal plates simple and not layered............................................ .. 3 - Body slender or stout, if stout, dorsal plates layered in the middle; if slender, the body more than 4.0 × as long as wide, head width across eyes wider than anterior margin of pronotum in males................................................................................all other species (including dozens of species will be treated in a forthcoming work) 3. Scutellum pitch black; male genitalia: ventral processes of parameres slender and bent inwards at apical part in ventral view, not thickened at apex, laterophyses tilting ventrally at an angle of more than 45° with dorsal plates, compressed and longitudinally divided at apical part ( S. laterophysus species-group)......................................................... 4 - Scutellum yellow; male genitalia: ventral processes of parameres stouter and diverging apically in ventral view, thickened at apex, laterophyses relatively parallel to dorsal plates, expanded apically, divided at apices ( S. notaticollis species-group)... 5 4. Head with a triangular marking on vertex, legs mostly yellow, black at apical part of femora and basal part of tibiae ( Fig. 1A ); male genitalia: ventral processes of parameres nearly as long as dorsal plates, laterophyses stout at basal part and abruptly narrowed apically in ventral view ( Švihla 2004 : fig. 146).................................. S. laterophysus Švihla, 2004 - Head with a longitudinal marking on vertex, legs mostly black, yellow at coxae, trochanters and basal part of femora ( Fig. 2A ); male genitalia: ventral processes of parameres longer than dorsal plates, laterophyse slender and evenly narrowed in ventral view ( Figs 3A‒C )..................................................................... S . nigritibius sp. nov. 5. Head and elytra pitch black, pronotum mostly pitch black, yellowish brown or reddish brown at anterior angles.......... 6 - Head and elytra pale-yellow or brown, pronotum pale-yellow with black brown markings on disc...................... 7 6. Male antennae shorter and slightly over elytral half-length, antennomeres II slightly longer than wide at apices, III more longer than II ( Fig. 2C ); male genitalia: strongly swollen laterally at basal part in ventral view, dorsal plates longer than ventral processes of parameres, with outer apical angles acute in dorsal view ( Figs 3G‒I ).................... S. acutiapicis sp. nov. - Male antennae longer and reaching apical one-third length of elytra, antennomeres II obviously longer than wide at apices, III less longer than II ( Fig. 2B ); male genitalia: moderately swollen laterally at basal part in ventral view, dorsal plates nearly as long as ventral processes of parameres, with outer apical angels subrounded in dorsal view ( Figs. 3D‒F ).................................................................................................. S. parameratus sp. nov. 7. Male genitalia: dorsal plates evenly narrowed apically, ventral processes with apices directing ventrally in ventral view ( Wittmer, 1974 : fig. 1)............................................................. S. notaticollis ( Gorham, 1895 ) - Male genitalia: dorsal plates abruptly narrowed in the middle, ventral processes with apices directing laterally in ventral view ................................................................................................... 8 8. Head and elytra uniformly pale-yellow, legs mostly yellow, tibiae and tarsi dark brown ( Švihla, 2011 : fig. 24); male genitalia: dorsal plates narrower and acute at apices, with nearly straight inner margins ( Švihla, 2011 : figs 105‒107).................................................................................................. S. tamil Švihla, 2011 - Head and elytra mostly black brown, with reddish brown marking on vertex, leg black brown, coxae, trochanters and basal part of femora yellowish brown; male genitalia: dorsal plates wider, subrounded at apices and widely emarginate at inner margins ( Wittmer, 1974 : fig. 3; Švihla, 2011 : figs 108‒109)..................................... S. bourgeoisi Wittmer, 1974