Omalium gildenkovi, Semionenkov & Shavrin, 2022

Semionenkov, O. I. & Shavrin, A. V., 2022, Omalium gildenkovi (Coleoptera: Staphylinidae: Omaliinae), a new species from the central part of European Russia, Caucasian Entomological Bulletin (Caucas. entomol. bull.) 18 (1), pp. 3-8 : 4-7

Omalium gildenkovi sp. n.

( Figs 1, 2 , 4, 5 , 10–15 )

Material. Holotype, ♂ ( Fig. 1 ; specimen without right elytron) (ZMM): “РОССИЯ: СмоΛенская обΛасть, Ершичский район, маршрут ПосеΛки-Ершичи-Рухань-Корсики. АвтомобиΛьная Λовушка. 15.V.2021. О. Семионенков” [ RUSSIA: Smolensk Region, Yershichi District , Poselki-Yershichi-Ruhan’-Korsiki route. Car net. 15.V.2021. O. Semionenkov] (printed), “HOLOTYPE Omalium gildenkovi sp.n. Semionenkov O.I. & Shavrin A. V. des. 2021” (red, printed) . Paratype: 1♀ ( Fig. 2 ; specimen damaged: right elytron, right protarsomeres 3–5, right metatibia and metatarsus are missing) (ZMM): “РОССИЯ: СмоΛенская обΛасть, Шумячский район, маршрут КраснопоΛье-Понятовка-Шумячи-Первомайский. АвтомобиΛьная Λовушка. 3.V.2020, О. Семионенков” [ RUSSIA: Smolensk Region, Shumyachi District , Krasnopolye-Ponyatovka-Shumyachi-Pervomayskiy route. Car net. 3.V.2020, O. Semionenkov] (printed), “PARATYPE Omalium gildenkovi sp.n. Semionenkov O.I. & Shavrin A. V. des. 2021” (red, printed) .

Description. Measurements (n = 2): maximum width of head including eyes 0.39–0.41; length of head (from base of labrum to posterior constriction along head midline) 0.28–0.32; length of antenna 0.64; ocular length (longitudinal) 0.11–0.14; length of temple 0.05–0.07; length of pronotum 0.36–0.38; maximum width of pronotum 0.49–0.52; sutural length of elytra (length of elytra from apex of scutellum to posterior margin of sutural angle) 0.57–0.6; maximum width of elytra 0.64; length of metatibia 0.29–0.3; length of metatarsus 0.17–0.19; maximum width of abdomen 0.61–0.63; length of aedeagus (from base of median lobe to apex of parameres) 0.39; length of forebody (from anterior margin of clypeus to apex of elytra) 2.11–2.42; total length (from anterior margin of clypeus to apex of abdomen) 2.25–2.7.

Body reddish-brown to dark brown, with paler lateral and basal portions of pronotum and apical portion of elytra (paratype paler); antennae reddish-brown (slightly paler in holotype); mouthparts, legs and intersegmental membranes between abdominal tergites yellow-brown; tarsi yellowish. Head with dense, moderately large and deep punctation, very fine and sparse in frontoclypeal portion, denser and coarser in middle, with interstices between punctures in middle about as long as diameters of nearest two punctures; neck with dense punctation, about as that in middle portion of head; punctation of pronotum about as that on head, denser in medioapical and distinctly sparser in middle and lateral portions (punctation of laterobasal portion of holotype very sparse), interstices between punctures in middle as broad as diameter of one-two nearest punctures; scutellum with several fine punctures; punctation of elytra distinctly larger, deeper and coarser than that on pronotum, finer and denser in parascutellar portions and along suture, with some merging punctures in medioapical portion forming indistinct longitudinal rows; abdomen with regular,fine and moderately dense punctation. Forebody without microsculpture; abdomen with distinct, dense, isodiametric microreticulation.

Head distinctly convex in middle and in portions between anteocellar foveae and eyes, 1.2–1.3 times as broad as long, with wide and moderately long diagonal impressions on lateral sides of clypeus; temples moderately long, about twice as long as longitudinal length of eyes, convex, temporal angles rounded, distinctly protruded laterobasad; each lateroapical portion with two moderately long ridges extending from above antennal insertion to level of apical third of eyes; anteocellar foveae very deep, wide, moderately short. Ocelli large, located below level of posterior margins of eyes; distance between ocelli slightly narrower than distance between ocellus and posterior margin of eye. Eyes moderately large, strongly convex, markedly longer than temples. Apical palpomere of maxillary palpi slightly more than twice as long as and about as broad as moderately short preapical segment. Antennae moderately short, reaching basal margins of pronotum when reclined, with antennomeres 5–9 progressively broadened apically; basal antennomere about twice as long as broad, antennomere 2 suboval, narrower than basal antennomere, 3 distinctly narrower and slightly shorter than 2, 4 small, slightly longer than broad and distinctly shorter than 3, 5 slightly broader than 4, 6 broader than 5, 7 broader and longer than 6, 8 slightly transverse, broader and shorter than 7, 9–10 slightly or distinctly transverse, broader than 8, apical antennomere about 1.4 times as long as 10, from apical third sharply narrowing toward subacute apex.

Pronotum 1.3 times as broad as long, 1.2 times as broad as head, widest in middle, gradually narrowing toward widely rounded anterior angles and relatively sharply narrowing toward subacute posterior angles; laterobasal margins in front of posterior angles slightly and widely concave; anterior margin widely rounded, slightly concave in front of anterior angles, about as long as posterior margin; paramedian impressions distinct, wide and long, extending from about apical third, slightly broadened basally and reaching basal third portion of pronotum; medioapical impression distinct, small, suboval, slightly elongate; lateral impressions distinct, deeper and broader in laterobasal potions.

Elytra moderately narrow, slightly broader than long, 1.5 times as long as pronotum, more or less parallel-sided, with widely rounded posterior margins.

Legs simple, with several short spines in apical portions of meso- and metatibiae; metatarsi 1.5–1.7 times as long as metatibia.

Abdomen slightly narrower than elytra, with two small oval tomentose spots in middle of abdominal tergite IV, with narrow palisade fringe at apical margin of abdominal tergite VII.

Male ( Fig. 1 ). Antennomeres 8–10 slightly elongate. Posterior margin of abdominal tergite VIII slightly ( Fig. 11 ) and sternite VIII ( Fig. 10 ) widely and deeply concave. Genital segment as in Fig. 14 . Aedeagus with wide basal portion and long, narrow, spear-shaped median lobe, from widest basal portion gradually narrowing toward subacute apex; apical portions of paired elongate sclerites connected with middle part of median lobe widely rounded; parameres wide, moderately short, narrowed apically, almost reaching preapical part of median lobe, apical part of each paramere with two long apical and short preapical setae; internal sac moderately narrow and long, with elongate, sclerotized sclerites in basal portion ( Fig. 4 ). Aedeagus laterally as in Fig. 5 ; median lobe forming hook-shaped apical portion, with wide apical and subacute preapical angles.

Female ( Fig. 2 ). Antennomeres 8–10 slightly transverse. Posterior margin of abdominal tergite VIII ( Fig. 13 ) and sternite VIII ( Fig. 12 ) somewhat straight. Genital segment as in Fig. 15 ; female accessory sclerite moderately wide, with suboval basal portion and rounded apex. Spermatheca not found.

Comparative diagnosis. Based on the morphology of the aedeagus and the shape of the anteocellar foveae, O. gildenkovi sp. n. belongs to the rivulare group of Omalium defined by Zanetti [1987]. Based on the small body and general shape of the median lobe, O. gildenkovi sp. n. is similar to two European species: O. exiguum ( Fig. 3 ) and O. funebre . From O. exiguum ( Figs 3 , 6, 7 , 16 ) it differs by the absence of microsculpture and denser punctation of the head and the presence of hook-shaped apex of the median lobe (in lateral view). From O. funebre ( Figs 8, 9 ) it differs by the paler colouration of femora, the absence of microsculpture on the forebody, and the shape of the hook of the apical portion of the median lobe ( Figs 5, 9 ). The general shape of the female accessory sclerite ( Fig. 15 ) of O. gildenkovi sp. n. is similar to that in O. funebre [ Zanetti, 1987: fig. 48m], but this sclerite in the latter species has narrower basal and somewhat broader apical parts. Besides that, based on the body size, colouration, general shape of the pronotum and the aedeagus, O. gildenkovi sp. n. is somewhat similar to O. cerrutii Zanetti, 1985 (= O. montivagum Eppelsheim, 1878 ), originally described from Central Italy [ Zanetti, 1985] and recorded from Georgia [ Zanetti, 2002]. However, the new species can be distinguished from O. cerrutii by the absence of microsculpture on the head and different shape of the median lobe [ Zanetti, 1985: figs 4–6, 9, 10; Zanetti, 2002: figs 22, 23).From all these species, O. gildenkovi sp. n. can be distinguished by the somewhat paler colouration, the shape of convex temples, distinctly protruded laterobasad, by narrower apical portion and the shape of the median lobe (lateral view), by the morphology of the internal sac, and by different shape of the female accessory sclerite.

Notes. The new species was collected in two localities with a distance of approximately 10 km from each other in Smolensk Region near the border with Belarus. Possibly, O. gildenkovi sp. n. is more widely distributed in the East European Plain. Bionomics for this species remains unknown.

Etymology. Patronymic, the species is named to honour our friend and colleague, staphylinidologist Mikhail Yu. Gildenkov (Smolensk, Russia).

Figures

Figs 1−3. Species of the genus Omalium, habitus. 1–2 – O. gildenkovi sp. n.: 1 – male, holotype, 2 – female, paratype; 3 – O. exiguum, male (Smolensk Region, Russia).Scale bars 1 mm. Рис. 1−3. ВиÃы роÃа Omalium, габитус. 1–2 – O. gildenkovi sp. n.: 1 – самец, гоΛотип,2 – самка, паратип;3 – O. exiguum, самец (СмоΛенская обΛасть,Россия).Масштабные Λинейки 1 мм.

Figs 4−9. Aedeagi of Omalium spp. 4−5 – O. gildenkovi, holotype; 6−7 – O. exiguum (Smolensk Region,Russia);8−9 – O.funebre (Alpi Carniche, Italy).4, 6, 8 – ventral view; 5, 7, 9 – lateral view. Scale bars 0.1 mm. Рис. 4−9.ЭÃеагусы Omalium spp. 4−5 – O. gildenkovi, гоΛотип; 6−7 – O. exiguum (СмоΛенская обΛасть,Россия); 8−9 – O. funebre (Карнийские АΛьпы, ИтаΛия).4, 6, 8 – виà снизу; 5, 7, 9 – виà сбоку.Масштабные Λинейки 0.1 мм.

Figs 10−16. Apical abdominal segments. 10−15 – Omalium gildenkovi; 16 – O. exiguum. 10 – male sternite VIII; 11 – male tergite VIII; 12 – female sternite VIII; 13 – female tergite VIII; 14 – male genital segment; 15−16 – female genital segment. Scale bars 0.1 mm. Рис. 10−16. Вершинные брюшные сегменты. 10−15 – Omalium gildenkovi; 16 – O. exiguum. 10 – стернит VIII самца; 11 –тергит VIII самца; 12 – стернит VIII самки; 13 – тергит VIII самки; 14 – генитаΛьный сегмент самца; 15−16 – генитаΛьный сегмент самки. Масштабные Λинейки 0.1 мм.