Omalium amicorum, 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 : 158-161

3.2.1.2.2. Omalium amicorum sp. n.

( Figs 3–4 , 10 , 19–22 )

Type material. Holotype ♁ (dissected): ‘ NEPAL Manaslu Mts. | 28°22’N 84°29’E | E slope of Ngadi | Khola Vall. | 2000–2300 m, leg. | [J.] Schmidt 15.V.2005 ’ <printed >, ‘ HOLOTYPE | Omalium | amicorum sp. n. | Shavrin A.V. des. 2023’ <red, printed> (NME).

Paratypes: 2 ♁♁ (one specimen dissected), 1 ♀: ‘ NEPAL, Dhaulagiri Himal | s-slope, N Banduk vill. | 1900– 2300m, 28°27’22’’N, | 83°35’13’’E to 28°28’07’’N | 83°35’10’’E, 06.V.2009 | leg. J. Schmidt’ <printed>, ‘collection | NATURKUNDE | MUSEUM ERFURT’ <yellow, printed> (1 ♁: cSh; 1 ♁, 1 ♀: NME) ; 2 ♀♀: ‘ NEPAL, S slope, Dhaulagiri | Mts. above Pathlekharka | 2500–2700 m, 12.V.2009 | 28°32’19’’N, 83°29’25’’E, | leg. J. Schmidt’ (1 ♀: cSh; 1 ♀: NME) ; 1 ♀ (left antennomeres 3–11 and left hind leg missing): ‘E. NEPAL: KOSI | 2 km E. Mangsingma | 1900 m, 19.IV.[19]84 | [I.] Löbl - [A.] Smetana [sifted moss and leaf litter]’ (MHNG) ; 1 ♀ (dissected): ‘E. NEPAL: KOSI | Val. Induwa Kola | 2050 m, 17.IV.[19]84 | [I.] Löbl - [A.] Smetana [bank of a river]’ <printed> (MHNG). All paratypes with additional red printed label: ‘ PARATYPE | Omalium | amicorum sp. n. | Shavrin A.V. des. 2023’.

Description. Measurements (n=7): HW: 0.59–0.62; HL: 0.42–0.47; OL: 0.17–0.20; TL: 0.07–0.09; AL (holotype): 1.37; PL: 0.51–0.57; PWmax: 0.74–0.75; PWmin: 0.63–0.70; ESL: 0.91–1.07; EW: 1.11–1.17; MTbL (holotype): 0.60; MTrL (holotype): 0.26 (MTrL 1–4: 0.11; MTrL 5: 0.15); AW: 0.91–1.10; AedL: 0.72–0.80; BL: 3.15–3.50 (holotype: 3.25).

Habitus as in Fig. 3 ; head and pronotum dorsolaterally as in Fig. 4 . Body reddish-brown, with distinctly darker head, sometimes with paler lateral portions of pronotum and abdomen; antennomeres 6–11 brown; mouthparts, antennomeres 1–5 and legs yellow-brown or slightly darker. Punctation of head moderately large and dense, finer and denser on apical portion of clypeus, markedly denser in middle between anteocellar foveae and slightly coarser on infraorbital portions (holotype with sparser median punctation); nuchal constriction with moderately dense and large punctation, sometimes finer in middle; punctation of pronotum dense, slightly larger and deeper than that in middle part of head, sparser and finer in medioapical and mediobasal portions; punctation of elytra dense, about as that on pronotum, denser around scutellum, finer and sparser along suture. Anterior portion of clypeus with very fine and sometimes indistinct transverse microreticulation; nuchal constriction with dense isodiametric meshes; pronotum and elytra without microsculpture; scutellum with fine isodiametric microreticulation.

Head 1.3–1.4 times as broad as long, with broad clypeus, distinctly convex supra-antennal elevations and strongly elevated middle portion between eyes and infraorbital portions, with very deep and wide anteriomedian depressions, sometimes significantly stretching posteriad and reaching apical part of anteocellar foveae; portions between infraorbital parts and middle deeply depressed. Surface without or with shallow elevations between anteocellar foveae, with slightly elevated narrow diagonal wrinkles on basal portions of clypeus, infraorbital portions without or with irregular longitudinal elevations between punctures. Anteocellar foveae very deep and wide, diagonally stretching apicad toward level of anterior third of eyes. Temples more than twice shorter than longitudinal length of eyes, strongly narrowed posteriad toward distinctly protruded basad subacute angles. Apical half of nuchal constriction significantly depressed, broader in middle; medioapical part of nuchal constriction strongly elevated, rounded, distinctly protruded antreriad ( Fig. 4 ). Ocelli very large, located close to basal impression, sometimes with concave strong depression between basal margins; distance between ocelli 1.6 times to twice as long as distance between ocellus and posterior margin of eye. Antenna with antennomeres 9–10 slightly transverse; antennomere 4 small, slightly longer than broad, shorter than 3, 5 slightly longer than 4, 6 slightly longer and indistinctly broader than 5, 7–8 slightly broader than 6, 8–9 distinctly broader than 7, apical antennomere 1.2–1.3 times as long as 10.

Pronotum distinctly convex, 1.3–1.4 times as broad as long, 1.2–1.5 times as broad as head, from widest apical third slightly narrowed anteriad and distinctly narrowed posteriad, with widely concave laterobasal margins, with apical angles indistinctly protruded anteriad. Anterior margin rounded, sometimes significantly protruded apicad in some specimens ( Fig. 4 ), about as long as straight or slightly rounded basal margin. Surface of disc with two strong, wide and deep longitudinal depression, significantly broadened posteriad, and with very deep oval depression in medioapical portion; lateral portions widely impressed, distinctly deeper laterobasally; surface between all pronotal depressions strongly elevated. Middle surface of disc with irregular and sometimes indistinct diagonal and transverse elevations between punctures.

Elytra slightly broader than long, 1.7–1.8 times as long as pronotum, distinctly broadened posteriad. Middle surface of each elytron with irregular diagonal and transverse elevations between punctures, coarser in parascutellar portion.

Abdomen narrower than elytra.

Male. Antennomeres 8–10 slightly transverse. Posterior margin of abdominal tergite VIII straight or slightly rounded. Posterior margin of abdominal sternite VIII slightly concave. Aedeagus with wide basal portion, gradually narrowed toward middle, with long and moderately narrow median lobe, from widest middle gradually narrowed apically toward small rounded apex; mediolateral portions with wide accessory plates widely broadened apically; parameres moderately wide, distinctly shorter than apex of median lobe, from widest middle distinctly narrowed apically toward small rounded apices, with three long apical and one preapical setae; internal sac wide and moderately long, without sclerotized structures in basal portion ( Fig. 20 ). Lateral aspect of the aedeagus as in Fig. 21 ; apical portion of median lobe moderately narrow, broadened in preapical portion, with curved acute apex and two obtuse teeth on inner side of preapical part ( Fig. 22 ).

Female. Antennomeres 8–10 less transverse. Posterior margin of abdominal tergite VIII straight. Posterior margin of abdominal sternite VIII rounded.Accessory sclerite short, with very wide basal portion, strongly narrowed toward subacute apex ( Fig. 10 ). Spermatheca not recognized.

Comparative notes. Omalium amicorum sp. n. can be distinguished from O. acutangulum sp. n. by the temples strongly narrowed posteriad, finer sculpture of middle and infraorbital portions of head, by the presense of an unusual deep impression in medioapical part and strongly elevated mediobasal part of nuchal constriction, narrower preapical part of the pronotum, and details of external and internal morphology of the aedeagus (see the key above).

Distribution. Omalium amicorum sp. n. is known from several localities in central and eastern Nepal ( Fig. 19 ).

Etymology. The specific epithet is the Latin amicorum , - a, - us (friends). The species is dedicated to A. Smetana and I. Löbl, collectors of several paratypes.

Bionomics. Specimens were collected at elevations from 1900 to 2700 m a.s.l. The specimen from Mangsingma was collected by sifting moss and leaf litter. The specimen from Induwa Kola was collected near the river.

Figures

FIGURE 19. Distribution of Omalium in the Himalayan region: O. acutangulum sp. n. (circles), O. amplissimum sp. n. (star), O. beesoni (squares), O. cariosum (diamonds), O. flavotestaceum sp. n. (triangles).

FIGURES 20–22. Aedeagus of Omalium amicorum (holotype): 20—aedeagus, parameral view, 21—aedeagus, lateral view, 22—median lobe, lateral view). Scale bar: 0.1 mm.

FIGURES 1–4. Habitus (Figs 1, 3) and dorsolateral view of head and pronotum (Figs 2, 4) of Omalium: 1–2—O. acutangulum (paratype), 3–4—O. amicorum (paratype). Scale bars: 1.0 mm.

FIGURES 8–18. Female accessory sclerite (Figs 8, 10–16, 18) and spermatheca (Figs 9, 17) of Omalium: 8–9—O. acutangulum, 10—O. amicorum, 11—O. amplissimum, 12—O. bilobum, 13—O. alticola, 14—O.beesoni, 15—O. altivagans, 16–17—O. marginatum, 18—O. scapulare. Scale bar: 0.1 mm.