Omalium latocavum, Shavrin, 2023

Shavrin, Alexey V., 2023, A revision of the genus Omalium Gravenhorst, 1802 (Coleoptera: Staphylinidae: Omaliinae) of the Himalayan region, Zootaxa 5369 (2), pp. 151-206 : 197-199

3.2.5.2.5. Omalium latocavum sp. n.

( Figs 69 , 81 , 90 , 93–95 )

Type material. Holotype ♁ (dissected): ‘N Mongeythanti | Bhanjyang 3600- | 4000m 19/20.5.[19]96’ <printed>, ‘ NEPAL SW Ganesh-H. | Abuthum Lekh , leg. | Ahrens, Kulbe, Rulik’ <printed>, ‘ HOLOTYPE | Omalium | latocavum sp. n. | Shavrin A.V. des. 2023’ <red, printed> (NME).

Paratypes: 1 ♁ (dissected), 1 ♀ (dissected): same data as the holotype, with additional red printed label : ‘ PARATYPE | Omalium | latocavum sp. n. | Shavrin A.V. des. 2023’ (1 ♁: cSh, 1 ♀: NME).

Description. Measurements (n=3): HW: 0.60–0.62; HL: 0.43–0.49; OL: 0.15; TL: 0.10–0.12; AL (holotype): 1.15; PL: 0.47–0.50; PWmax: 0.71–0.72; PWmin: 0.67; ESL: 0.90–0.96; EW: 0.92–0.97; MTbL (holotype): 0.55; MTrL (holotype): 0.22 (MTrL 1–4: 0.09; MTrL 5: 0.13); AW: 0.90–0.95; AedL: 0.70–0.72; BL: 3.06 (holotype)– 3.28.

Habitus as in Fig. 90 . Body reddish-brown, with slightly paler lateral and basal portions of pronotum, elytra and abdomen; antennomeres 6–11 brown; mouthparts, antennomeres 1–5 and legs yellow. Punctation of head moderately small and sparse, denser in middle and coarser on infraorbital portions; punctation of pronotum moderately dense, larger and deeper than that of middle portion of head, slightly finer in middle and sparser in mediobasal third; elytra with dense and coarse punctation, slightly larger and deeper than that on pronotum, finer and sparser along suture. Anterior portion of clypeus with fine transverse microreticulation; pronotum and elytra without microsculpture; scutellum with fine isodiametric meshes.

Head 1.2–1.3 times as broad as long, with broad clypeus and slightly convex supra-antennal elevations, lateral portions of clypeus with wide shallow anteriomedian depressions, reaching level of anterior third of eyes. Surface with elongate elevations in middle and slightly stronger longitudinal wrinkles between punctures on infraorbital portions. Anteocellar foveae very deep and wide, oval, short, reaching level of posterior third of eyes. Temples 1.2–1.5 times as long as longitudinal length of eyes. Distance between ocelli distinctly more than twice as long as distance between ocellus and posterior margin of eye. Antennomeres 4–5 distinctly shorter than 3, about as long as broad, 6 longer and broader than 5, 7–8 distinctly broader than 6, 9–10 longer and broader than 8, apical antennomere 1.3 times as long as 10, from about middle gradually narrowed toward rounded or subacute apex.

Pronotum moderately narrow, 1.4–1.5 times as broad as long, from widest apical middle gradually narrowed both posteriad and anteriad. Surface of disc with two very deep and wide longitudinal depressions, slightly broadened posteriad toward mediobasal third, and with additional oval shallow or very deep depression in medioapical third. Median surface between outer margins of longitudinal depressions and lateral portions with irregular longidudinal elevations between punctures (holotype without these elevations).

Elytra slightly broader than long, slightly less than twice as long as pronotum, subparallel in middle or slightly broadened posteriad, with slightly concave lateral margins in middle.

Male. Antennomeres 9–10 sligthly transverse. Posterior margin of abdominal tergite VIII straight or rounded. Posterior margin of abdominal sternite VIII rounded. Aedeagus with wide basal portion, gradually narrowed toward middle, with long moderately narrow spear-shaped median lobe, slightly broadened in apical portion, with irregularly crenulate lateral margins and rounded apex, each preapical margins forming tooth indistinctly protruded laterobasad; mediolateral portions with narrow elongate sclerotized accessory plates connected with median and preapical portions of parameres; parameres significantly shorter than apex of median lobe, strongly broadened apically, with slightly asymmetric apical portions and broad apices, each with four moderately long apical setae; internal sac moderately wide and long, with four sclerotized transverse structures in basal portion ( Fig. 93 ). Lateral aspect of the aedeagus as in Fig. 94 ; apical part of median lobe narrow, inner margin forming distinct hook with subacute hind angle, preapical inner margin crenulate, with rounded and slightly curved apex ( Fig. 95 ).

Female. Antennomeres 9–10 less transverse. Posterior margin of abdominal tergite VIII and sternite VIII rounded. Accessory sclerite leaf-shaped, from widest basal portion gradually narrowed toward small rounded apex. Spermatheca not recognized.

Comparative notes. Regarding the general shape of the pronotum gradually narrowed both apicad and posteriad, O. latocavum sp. n. is similar to O. secretum , from which it can be distinguished by the slightly larger body, the elytra slightly less than twice as long as pronotum, denser and coarser sculpture of the pronotum and the elytra, and details of the morphology of the aedeagus (see the key above).

Distribution. Omalium latocavum sp. n. is known only from the type locality in central Nepal ( Fig. 69 ).

Etymology. The specific epithet is the Latin latocavus, - a, - um (wide hole). It alludes to the coarse punctation of the elytra.

Bionomics. Specimens were collected at elevations from 3600 to 4000 m a.s.l. Specimens were collected under stones along the main ridge.

Figures

FIGURE 69. Distribution of Omalium in the Himalayan region: O. angustissimum sp. n. (circle), O. kumari sp. n. (triangles), O. latocavum sp. n. (diamond).

FIGURES 76–83. Female accessory sclerite (Figs 76–77, 79, 81–82) and spermatheca (Figs 78, 80, 83) of Omalium: 76— O.cariosum, 77–78—O. flavotestaceum, 79–80—O. kumari, 81—O. latocavum, 82–83—O. secretum. Scale bar: 0.1 mm.

FIGURES 90–92. Habitus of Omalium: 90—O. latocavum (paratype), 91—O. nigrum (holotype), 92—O. secretum (Nepal: Parbat). Scale bars: 1.0 mm.

FIGURES 93–95. Aedeagus of Omalium latocavum (holotype): 93—aedeagus, parameral view, 94—aedeagus, lateral view, 95—median lobe, lateral view. Scale bar: 0.1 mm.