Omalium cariosum Cameron, 1924

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 : 189-192

3.2.5.2.2. Omalium cariosum Cameron, 1924

( Figs 19 , 70 , 73–76 )

Omalium (s. str.) cariosum Cameron, 1924: 167 ; Scheerpeltz 1933: 1044

Type material. Lectotype (here designated) of Omalium (s. str.) cariosum Cameron, 1924 ♀ ( Fig. 70 ): ‘Type | H.T.’ <round label with red margins, printed>,‘Dehra Dun | Dr. Cameron | 21. 3. [handwritten] 1922.’ <printed>, ‘ Omalium | cariosum | Cam..’ <handwritten>, ‘ M.Cameron. | Bequest. | B.M.1955-147.’ <printed>, ‘NHMUK014663259’ <printed label, with barcode on the right side >, ‘ LECTOTYPE | Omalium (s. str.) | cariosum Cameron, 1924 | Shavrin A.V. des. 2023 <red, printed>‘, ‘ Omalium | cariosum Cameron, 1924 | Shavrin A.V. det. 2023’ <printed> (BMNH).

Paralectotype: 1 ♁ (dissected): ‘Dehra Dun. | Dr. Cameron | 4. 3. [handwritten] 1922.’ <printed>, M.Cameron. | Bequest. | B.M.1955-147.’ <printed>, ‘ Omalium | cariosum Cameron, 1924 | Shavrin A.V. det. 2023’ <printed> (BMNH) .

Additional material examined. INDIA: UTTARAKHAND: 1 ♀: ‘ Co - | type’, ‘ United Prov., N. India. B.M. 1924- 335.’, ‘ Woodstock Falls , Mussoorie. Dr. Cameron. 27.III.1921.’, ‘ Omalium cariosum, Cam. Co. type’, ‘locality not mentioned in description! M.K. Thayer 1989’, ‘NHMUK014663258’ (BMNH) .

Redescription. Measurements (n=3): HW: 0.42–0.46; HL: 0.31–0.33; OL: 0.14; TL: 0.06; AL (lectotype): 0.83; PL: 0.40; PWmax: 0.57; PWmin: 0.49; ESL: 0.72; EW: 0.72–0.75; MTbL (lectotype): 0.35; MTrL (lectotype): 0.17 (MTrL 1–4: 0.07; MTrL 5: 0.10); AW: 0.72–0.75; AedL: 0.52; BL: 2.85–3.15 (lectotype).

Habitus as in Fig. 70 . Head, pronotum and abdomen reddish-brown (head slightly darker; apical tergites of abdomen and paratergites distinctly paler); lateral and basal portions of pronotum and elytra yellow-brown; antennomeres 6–11 brown; mouthparts, antennomeres 1–5 and legs yellowish. Punctation of head dense and moderately large, denser in middle and on infraorbital portions (paralectotype with slightly sparser punctation in middle); punctation of pronotum about as that in middle portion of head or slightly larger and deeper, distinctly finer and sparser in mediobasal portion; scutellum without punctures; punctation of elytra dense, about as that on head or slightly coarser, slightly finer and sparser along suture; abdominal tergites without or with very indistinct, sparse and fine punctation. Apical portion of clypeus with fine trasverse meshes, latero-apical portion of clypeus between middle and supra-antennal portions with subdiagonal meshes, middle portion of head between eyes and infraorbital portions without distinct microsculpture; pronotum, scutellum and elytra without microreticulation.

Head with supra-antennal elevations indistinctly elevated and moderately narrow clypeus stretching posteriad toward level of middle length of eyes. Lateral portions of clypeus with moderately shallow and long anteriomedian depressions. Middle portion between eyes slightly and posterior parts of infraorbital portions distinctly elevated. Middle surface between eyes with narrow diagonal and infraorbital portions with irregular longitudinal elevations between punctures (paralectotype without sculpture); each lateral portion near posterior margins of eyes with indistinct one to two elongate wrinkles. Anteocellar foveae deep and relatively long, slightly convergent latero-apicad toward level of middle length of eyes. Temples very short, distinctly more than twice shorter than longitudinal length of eye, strongly narrowed posteriad toward nuchal constriction. Ocelli located about at level of postocular ridges, distance between ocelli slightly less than twice as distance between ocellus and posterior margin of eye. Antennomere 3 about as long as 2, 4 small, about twice shorter than 3, 5 slightly broader than 4, 6 slightly broader and longer than 5, 7 slightly broader than 6, 8 indistinctly broader and longer than 7, 9–10 distinctly longer and broader than 8.

Pronotum 1.4 times as broad as long, 1.2–1.3 times as broad as head, widest in middle, gradually narrowed posteriad, with widely rounded apical angles not protruded anteriad. Surface of disc with two indistinct wide longitudinal depressions. Surface with distinct diagonal elevations in middle and between longitudinal depression and lateral portions.

Elytra disitinctly broader than long, 1.8 times as long as pronotum, subparallel. Medioapical portion of each elytron with slightly elevated between punctures (lectotype).

Metatarsi twice shorter than metatibia.

Abdomen about as broad as elytra.

Male. Antennomeres 9–10 strongly transverse. Posterior margins of abdominal tergite VIII slightly and sternite VIII distinctly and widely sinuate. Aedeagus with wide basal portion, gradually narrowed toward middle, with elongate and moderately narrow median lobe, from basal portion significantly narrowed apicad and from about middle forming elongate spear-shaped apical part; mediolateral portions with elongate sclerotized accessory plates slightly curved and rounded apically; parameres very wide, significantly shorter than apex of median lobe, with narrow and elongate apical portions and sclerotized inner lateral margins, each paramere with two long apical and one short preapical setae; internal sac moderately narrow and long, with narrow elongate sclerotized structure in middle of basal part ( Fig. 73 ). Lateral aspect of aedeagus as in Fig. 74 ; median lobe with subacute hook in apical part, with rounded apex ( Fig. 75 ).

Female. Antennomeres 9–10 less transverse. Posterior margins of abdominal tergite VIII and sternite VIII truncate. Accessory sclerite with very wide basal portion, gradually narrowed apicad toward subacute angle ( Fig. 76 ). Spermatheca not recognized.

Comparative notes. Based on the general shape of temples, gradually narrowed toward nuchal constriction, O. cariosum is similar to O. flavotestaceum sp. n., from which it can be distinguished by the distinctly shorter temples, the shape of the pronotum widest in the middle portion, slightly narrower elytra, and details of the morphology of the aedeagus (see the key above).

Distribution. Omalium cariosum is known from two localities in Uttarakhand, India ( Fig. 19 ).

Bionomics. Type specimens were collected at elevation about 1980 m a.s.l. The detailed binomical data are unknown.

Remarks. Omalium (s. str.) cariosum was originally described from “Dehra Dun: Mussorie, 6500 feet above the sea” based on the unspecified number of the syntypes. I designate here the female ( Fig. 70 ) with the round label “Type H.T.” as the lectotype in order to fix the identity of the name. The female with the round label with yellow margins (from “Woodstock Falls, Mussoorie”) does not belong to the type series due the different locality.

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 73–75. Aedeagus of Omalium cariosum (paralectotype): 73—aedeagus, parameral view, 74—aedeagus, lateral view, 75—median lobe, lateral view. Scale bar: 0.1 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.