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 3.2.3. Omalium sectum sp. nov. ( Figs 3 , 10–12 , 30 ) Type material examined. Holotype ♂ ( Fig. 3 ; dissected): 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 | sectum sp. nov. | Shavrin A.V. des. 2025’ <red, printed> ( cSch ). Description. Measurements: HW: 0.62; HL: 0.43; OL: 0.17; TL: 0.12; AL: 1.35; PL: 0.55; PWmax: 0.72; PWmin: 0.67; ESL: 1.01; EW: 1.16; MTbL: 0.35; MTrL: 0.17 (MTrL 1–4: 0.07; MTrL 5: 0.10); AW: 1.02; AedL: 0.70; BL: 3.54. Habitus as in Fig. 3 . Body reddish-brown, with slightly paler abdomen; antennomeres 6–11 brown; mouthparts, antennomeres 1–5 and legs yellow-brown. Punctation of head dense, denser and coarser in middle and on infraorbital portions; neck with moderately fine and sparse punctation; punctation of pronotum fine and sparse, sparser in medioapical, lateral and mediobasal portions; punctation of pronotum distinctly denser than that on pronotum, coarser in middle; abdominal tergites without punctation. Clypeus with fine transverse microsculpture; scutellum with fine isodiametric microreticulation; abdomen with dense isodiametric sculpture. Head 1.4 times as broad as long, with broad and deep anteriomedian depressions; posteriolateral margins of clypeus stretching toward level of middle length of eyes. Latero-apical margin between anterior margin of eyes and clypeus with small semicircular notch. Dorsal surface with distinct transverse and longitudinal elevations between punctures in middle and irregular elongate elevations on postocular parts. Anteocellar foveae very wide and deep, somewhat elongate, reaching level of posterior third length of eyes. Temples 1.4 times as long as longitudinal length of eye, from posterior margin of eyes gradually narrowed posteriad, each with distinct subacute angle protruded basad. Apical part of neck relatively deeply depressed, with short irregular and narrow longitudinal elevations. Distance between ocelli 1.7 times as long as distance between ocellus and posterior margin of eye. Apical maxillary palpomere about three times as long as penultimate segment. Antenna with distinctly elongate antennomeres 2–8 and slightly elongate 9–10; antennomere 3 slightly longer and narrower than 2, 4 distinctly shorter than 3, 5 longer than 4, 6–7 longer and distinctly broader than 5, 8 slightly shorter than 7, 9–10 slightly shorter and distinctly broader than 8, apical antennomere slightly longer than 10. Pronotum 1.3 times as broad as long, 1.1 times as broad as head, from widest anterior portion gradually narrowed posteriad toward widely rounded hind angles. Anterior angles acute and protruded anteriad. Anterior margin rounded, distinctly protruded anteriad. Each laterobasal portion not concave. Surface of disc with two wide and deep longitudinal and oval and deep anteriomedian depressions; surface between all depressions strongly elevated. Middle portion with irregular indistinct elevations. Elytra 1.1 times as broad as long, 1.8 times as long as pronotum, from basal portion distinctly broadened posteriad; hind margins straight. Dorsal surface of each elytron with irregular elevations, diagonal in medioapical and median, and longitudinal in apical portions. Metatarsi slightly less than twice as long as metatibia. Abdomen slightly narrower than elytra, with wide intersegmental membranes between abdominal tergites V– VI. Male. Posterior margin of abdominal tergite VIII straight. Posterior margin of abdominal sternite VIII sinuate. Aedeagus with wide basal portion, gradually narrowed toward median lobe; median lobe moderately long, from narrow basal part significantly broadened slightly in front middle, strongly narrowed in preapical part and broadened in apical portion, with widely rounded apex; accessory plates narrow, curved and relatively long, rounded apically; parameres wide and long, reaching apical part of median lobe, from widest preapical parts gradully narrowed apically, each with two moderately short apical and two preapical setae; internal sac narrow and long, without sclerotized structures ( Fig. 10 ). Lateral aspect of the aedeagus as in Fig. 11 ; apical portion of median lobe (lateral view) with crenulate ventrolateral margin ( Fig. 12 ). Female unknown. Comparative notes. Omalium sectum sp. nov. differs from the remaining species of the acutangulum group by the shape of the pronotum with acute anterior angles protruded anteriad, and the shape of the median lobe. Distribution. Omalium sectum sp. nov. is known from one locality in Meili Xue Shan and Diancang Shan mountain ranges in Yunnan , China ( Fig. 30 ). Etymology. The specific epithet is the Latin sectus , - a , - um (divided). It alludes to the shape of the median lobe. Bionomics. Specimens were collected at elevation 2580 m a.s.l. and was sifted from leaf litter, debris and mosses. It was collected together with O. rutilum sp. nov. and O. tibetanum sp. nov.