Review of the genus Omalium Gravenhorst, 1802 (Coleoptera: Staphylinidae: Omaliinae: Omaliini) of China Author Shavrin, Alexey V. 0000-0001-6487-4530 Institute of Life Sciences and Technologies, Daugavpils University, Vienibas 13, Daugavpils, LV- 5401, Latvia ashavrin@hotmail.com text Zootaxa 2025 2025-02-18 5588 4 501 543 https://doi.org/10.11646/zootaxa.5588.4.1 journal article 308253 10.11646/zootaxa.5588.4.1 e8d80c74-68cf-4598-9172-65280e118626 1175-5326 14896684 444F5F59-9228-4100-9135-DF824FF9BACA 3.2.2. Omalium rutilum sp. nov. ( Figs 2 , 7–9 , 14–15 , 30) Type material examined. Holotype ♂ : CHINA : YUNNAN : ‘CHINA: N-Yunnan [C2005-09] | Diqing Tibet. Aut. Pref., | Deqin Co. , Meili Xue Shan , | E-side, 14 km W Deqin , 2580 m ,’ <printed>, ‘ 28°27.47´N , 98°46.35´E , creek | valley below glacier, mixed forest, | leaf litter, moss, dead wood, sifted, | 11.VI.2005 , M. Schülke [C2005-09]’ <printed>, ‘Museum für Naturkunde | Berlin | Sammlung M. Schülke’ <printed>, ‘HOLOTYPE | Omalium | rutilum sp. nov. | Shavrin A.V. des. 2025’ <red, printed> ( cSch ). Paratypes ( 1 ♂ , 2 ♀♀ ): YUNNAN : 1 ♀ (dissected; both antennes missing): same data as the holotype ( cSh ) ; 1 ♀ : ‘ CHINA : N-Yunnan Diqing Tibet | Aut.Pr. Deqin Co. Meili Xue | Shan E-side 14 km W Deqin | 28°27.47´N , 98°46.35´E 2580m | 11.VI.2005 A. Smetana [C158]’ ( CNC ) ; 1 ♂ (dissected ; right elytron missing): ‘ CHINA ( Yunnan ) | Dali Bai Auton. Pref ., | Diancang Shan W Dali | 25°41´20´´N / 100°06´12´´E | 3160 m (small creek valley, | litter and debris sifted | 27.V.2007 D.W.Wrase [02]’ <printed>, ‘Museum für Naturkunde | Berlin | Sammlung M. Schülke’ <printed> ( cSch ). All paratypes with additional red printed label: ‘ PARATYPE | Omalium | rutilum sp. nov. | Shavrin A.V. des. 2025’. Description. Measurements (n=4): HW: 0.56–0.62; HL: 0.37–0.42; OL: 0.15–0.16; TL: 0.10–0.12; AL ( holotype ): 1.15; PL: 0.37–0.49; PWmax: 0.66–0.76; PWmin: 0.60–0.72; ESL: 0.83–0.90; EW: 0.87–1.10; MTbL ( holotype ): 0.47; MTrL ( holotype ): 0.20 (MTrL 1–4: 0.09; MTrL 5: 0.11); AW: 0.85–1.11; AedL: 0.47; BL: 2.57– 3.10 ( holotype : 2.70). Habitus as in Fig. 2 . Body reddish-brown, with distinctly darker head and abdomen; antennomeres 7–11 brown; mouthparts and antennomeres 1–6 yellow-brown; lateral portions of pronotum, lateral and apical portions of elytra, paratergites of abdomen and legs yellowish (tarsi slightly paler). Punctation of head dense, coarse and deep, denser and coarser in middle and on infraorbital portions, with interspaces between punctures in middle slightly less than diameter of nearest puncture; punctation of pronotum about as that in middle portion of head, but slightly larger, more irregular, slightly finer and sparser in middle and finer and sparser in mediobasal portion, with interspaces between punctures in middle about as long as diameter of nearest puncture; punctation of elytra slightly sparser and distinctly larger and deeper than that on pronotum, denser in mediobasal and mediolateral part, finer and sparser along suture and in medioapical portion. Anterior portion with distinct transverse microreticulation, middle part of clypeus with fine transverse and supra-antennal elevations with diagonal sculpture; mediobasal part of neck with transverse meshes; scutellum with dense and fine transverse microsculpture; abdomen with dense isodiametric sculpture. Apical and basal margins of pronotum with row of short cuticular fringe. Head 1.4–1.5 times as broad as long, with strongly elevated supra-antennal elevations and wide and deep anteriomedian depressions. Dorsal surface with strong longitudinal elevations between punctures, distinctly diagonal in laterobasal parts of clypeus and on infraorbital portions; postocular parts with irregular longitudinal wrinkles. Anteocellar foveae narrow and deep, somewhat subparallel, almost reaching level of middle length of eyes. Temples 1.3–1.5 times as long as longitudinal length of eyes, each with subacute posterior angle protruded basad. Medioapical part of neck narrowly and slightly depressed, with short and narrow elevations. Distance between ocellus 1.5–1.7 times as long as distance between ocellus and posterior margin of eye. Apical palpomere about three and a half times as long as penultimate segment. Antenna with slightly elongate antennomeres 7–8 and distinctly transverse 9–10; antennomere 3 about as long as and distinctly narrower than 2, 4 distinctly shorter and slightly narrower than 3, 5 slightly longer than 4, 6 distinctly longer than 5, 7 indistinctly broader than 6, 8 slightly broader than 7, 9–10 distinctly broader than 8, apical antennomere slightly longer than preapical antennomere, from middle gradually narrowed toward rounded apex. FIGURES 4–12. Aedeagus of Omalium (Figs 4–6— O. anguliferum (paratype), Figs 7–9— O. rutilum (paratype), 10–12— O. sectum (holotype)): 4, 7, 10—aedeagus, parameral view, 5, 8, 11—aedeagus, lateral view, 6, 9, 12—median lobe, lateral view. Scale bar: 0.1 mm. Pronotum transverse, 1.5–1.7 times as broad as long, widest in anterior third, gradually narrowed posteriad. Laterobasal portions not concave in front of obtuse hind angles. Lateral and laterobasal portions deeply and widely impressed. Surface of disc with two long and deep longitudinal depression, distinctly broadened and deepened basad; medioapical part with deep oval depression; surface between all pronotal depressions strongly elevated. FIGURES 13–29. Female accessory sclerite (Figs 13–14, 16, 18, 20–22, 24, 26, 28, 30) and spermatheca (Figs 15, 17, 19, 23, 25, 27, 29) of Omalium : 13— O. anguliferum , 14–15— O. rutilum , 16–17— O. cocleare , 18–19— O. contiger , 20— O . kurbatovi , 21— O. schuelkei , 22–23— O. bambusaphilum , 24–25— O. confertum , 26— O . lama , 27–28— O. rougemonti , 29— O. smetanai . Scale bar: 0.1 mm . Elytra slightly less than twice or slightly more than twice as long as pronotum, lateral margins narrowly impressed; hind margins straight. Dorsal surface of each elytron with strong irregular elevations, finer in middle. Male. Posterior margin of abdominal tergite VIII somewhat straight. Posterior margin of abdominal sternite VIII sinuate. Aedeagus with wide basal portion, slightly narrowed toward median lobe; median lobe moderately narrow, from widest middle gradually narrowed toward relatively small rounded apex; accessory plates narrow, moderately short and slightly curved apically; parameres wide, broadened in preapical part, each with two long and two short apical setae; internal sac moderately wide, long, without elongate sclerotized structures ( Fig. 7 ). Lateral aspect of the aedeagus as in Fig. 8 ; apical portion of median lobe elongate (lateral view), without ventrolateral teeth ( Fig. 9 ). Female. Posterior margin of abdominal tergite VIII truncate. Posterior margin of abdominal sternite VIII widely rounded. Accessory sclerite with wide basal portion and short median part, strongly narrowed toward acute apex ( Fig. 14 ). Spermatheca as in Fig. 15 . Comparative notes. Based on the shape of postocular portions of head and the shape of the apical part of the pronotum with apical angles slightly protruded apicad, O. rutilum sp. nov. is similar to Nepalese O. acutangulum and Chinese O. anguliferum sp. nov. Based on general shapes of the body, the aedeagus and the female accessory sclerite, it is more similar to O. acutangulum , from which it can be distinguished by the paler body, finer longitudinal elevations of median part of the head, denser punctation of the pronotum and the elytra, slightly shorter median lobe, broader parameres, and other details of the external and internal morphology of the aedeagus. From O. anguliferum sp. nov. , it differs by the narrower antennomere 8, the shape of more transverse pronotum, widest in anterior third and with more pronounced dorsal (including medioapical) impressions, and different morphology of the aedeagus and the female accessory sclerite. Distribution. Omalium rutilum sp. nov. is known from three localities in Qinling Shan mountain range in Shaanxi and in Meili Xue Shan and Diancang Shan mountain ranges in Yunnan , China ( Fig. 30 ). Etymology. The specific epithet is the Latin adjective rutilus , - a , - um (reddish). It alludes to the coloration of the body. Bionomics. Specimens were collected at elevations from 2580 to 3160 m a.s.l. and were sifted from leaf litter, debris and mosses. One specimen was collected by sifting of wet leaf litter, debris and moss on and around small seepages and on edges of a small creek in a mixed broadleaved forest (C158). It was collected in Meili Xue Shan together with O. sectum sp. nov. and O. tibetanum sp. nov.