Omalium flavotestaceum, 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 : 192-194

3.2.5.2.3. Omalium flavotestaceum sp. n.

( Figs 19 , 71 , 77–78 , 84–86 )

Type material. Holotype ♁: ‘ INDIA W. Bengal | Darjeeling distr. | Tonglu 3100m 16.X. | [C.] Besuchet-[I.]Löbl [sifted litter under busges in a pasture]’ <printed >, ‘ HOLOTYPE | Omalium | flavotestaceum sp. n. | Shavrin A.V. des. 2023’ <red, printed> (MHNG).

Paratypes: 1 ♀: same data as the holotype (MHNG); 1 ♁ (dissected) , 1 ♀ (dissected): ‘ INDIA, West Bengal | Darjeeling, Tonglu | 19.–23.V.1998 | 2600–3000m NN | leg. Fabrizi & Ahrens [under stones along a main ridge]’ (1 ♁: cSh; 1 ♀: NME); 1 ♁ (dissected) , 1 ♀ (dissected): ‘E-NEPAL, D: Taplejeung | E-slope Pathibara | 3500–3750m, 13.V. | 2016, leg. J.Schmidt | 27°26’N, 87°46’E’ (1 ♁: cSh; 1 ♀: NME). All paratypes with additional red printed label : ‘ PARATYPE | Omalium | flavotestaceum sp. n. | Shavrin A.V. des. 2023’.

Description. Measurements (n=6): HW: 0.55–0.58; HL: 0.42–0.46; OL: 0.15–0.16; TL: 0.10–0.11; AL (holotype): 0.98; PL: 0.41–0.49; PWmax: 0.65–0.72; PWmin: 0.55–0.64; ESL: 0.80–0.92; EW: 0.85–0.99; MTbL (holotype): 0.45; MTrL (holotype): 0.19 (MTrL 1–4: 0.08; MTrL 5: 0.11); AW: 0.85–1.01; AedL: 0.42; BL: 2.49 (holotype)–3.55.

Habitus as in Fig. 71 . Head and antennomeres 6–11 brown; pronotum, elytra and abdomen yellow-brown to reddish-brown (lateral portions of pronotum and paratergites paler; abdomen in some paratypes with yellowish middle parts of abdominal tergites IV–VII); mouthparts and antennomeres 1–5 yellow-brown; legs yellowish, with yellow tarsi. Punctation of head very dense, large and deep, coarser and larger between eyes; nuchal constriction with dense large punctation; punctation of pronotum denser, larger and deeper than that in middle portion of head, sparser in lateral portions, along midline and in mediobasal third; punctation of elytra dense, slightly larger and deeper than that on pronotum, sparser along suture. Anterior portion of clypeus with fine transverse and supra-antennal elevations with diagonal 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 strongly convex supra-antennal elevations, with very wide and deep anteriomedian depressions. Dorsal surface with distinct elevations in middle and on infraorbital portions: middle area between anteocellar foveae with irregular longitudinal elevations between punctures, portions between anteocellar foveae and eyes with narrow diagonal and moderately long wrinkles, infraorbital portions with three irregular strongly elevated longitudinal wrinkles; portions between posterior margins of eyes and temples with two to three long slightly elevated wrinkles curved posterolaterad. Anteocellar foveae deep and moderately long, slightly convergent latero-apicad, reaching level of middle or anterior third of eyes. Temples about twice shorter than longitudinal length of eyes, without postocular ridges. Distance between ocelli slightly more than twice as long as distance between ocellus and posterior margin of eye. Antenna with antennomeres 6–10 progressively broadened apicad, with slightly transverse antennomeres 9–10; antennomere 5 indistinctly broader than 4, 6 slightly longer and broader than 5, 7 slightly broader than 6, 8 distinctly broader than 7, 9–10 broader than 8, apical antennomere 1.2–1.3 times as long as 10, from about middle strongly narrowed toward subacute apex.

Pronotum 1.4–1.5 times as broad as long, 1.1–1.2 times as broad as head, from widest apical third more narrowed posteriad than anteriad. Apical angles indistinctly protruded anteriad. Anterior margin widely rounded. Lateral margins widely impressed, deeper in mediolateral portions. Surface of disc with two shallow or deeper and wider longitudinal depressions and oval depression in medioapical portion. Median portion with irregular transverse or diagonal elevations between punctures.

Elytra slightly broader than long, about twice as long as pronotum, slightly broadened posteriad. Middle surface of each elytron with strong irregular elevations between punctures, finer along suture.

Male. Proportions of preapical antennomeres about as these in females. Posterior margin of abdominal tergite VIII straight or rounded. Posterior margin of abdominal sternite VIII sinuate. Aedeagus with wide basal portion, gradually narrowed toward middle, with long moderately narrow spear-shaped median lobe, with rounded apex; mediolateral portions with elongate sclerotized accessory plates slightly curved and with rounded apices; parameres moderately short, significantly shorter than apex of median lobe, distinctly broadened toward preapical portions and from preapical portions gradually narrowed toward rounded apices, with two moderately long apical and two preapical setae; internal sac narrow and moderately long, without sclerotized structures ( Fig. 84 ). Lateral aspect of the aedeagus as in Fig. 85 ; apical portion moderately wide, rounded apically ( Fig. 86 ).

Female. Posterior margin of abdominal tergite VIII and sternite VIII rounded. Accessory sclertite with very wide basal portion, strongly narrowed toward moderately long and narrow elongate median part, gradually narrrowing toward acute apex. Spermatheca as in Fig. x.

Comparative notes. Based on the general shape of the temples, distinctly narrowed toward nuchal constriction, O. flavotestaceum sp. n. is similar to O. cariosum , from which it can be distinguished by the slightly longer temples, the shape of the pronotum widest in apical third, slightly broader elytra, and details of the morphology of the aedeagus (see the key above). Based on the general shape of the pronotum widest in apical third, O. flavotestaceum sp. n. is somewhat similar to O. kumari sp. n., from which it differs by the paler coloration of the body, shape of the nuchal constriction and different external and internal morphology of the aedeagus.

Distribution. Omalium flavotestaceum sp. n. is known from two localities in Pothibara Mt. in eastern Nepal and Darjeeling in West Bengal ( Fig. 19 ).

Etymology. The specific epither is the Latin flavotestaceus, - a, - um (yellowish red). It alludes to the coloration of the body.

Bionomics. The type specimen was collected at elevations from 2600 to 3750 m a.s.l. Specimens from West Bengal were taken by sifting litter under bushes in a pasture or were collected under stones along the main ridge.

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 70–72. Habitus of Omalium: 70—O. cariosum (lectotype), 71—O. flavotestaceum (paratype), 72—O. kumari (paratype). Scale bars: 1.0 mm.

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 84–86. Aedeagus of Omalium flavotestaceum (paratype): 84—aedeagus, parameral view, 85—aedeagus, lateral view, 86—median lobe, lateral view. Scale bar: 0.1 mm.