Omalium khmericum, Shavrin, 2020

Shavrin, Alexey V., 2020, New species and records of Paraphloeostiba Steel, 1960 from China and Laos and descriptions of four new species of related genera (Coleoptera: Staphylinidae Omaliinae: Omaliini), Zootaxa 4890 (3), pp. 301-329 : 319-322

Omalium khmericum sp.n.

( Figs. 43–50 )

Type material examined: Holotype Ƌ: ‘LAOS—Houa Phan prov., | Phu Phan Mt. , 20°12’N, | 104°01’E, ca. 1750 m, | 17.V.–3.VI.2007, | leg. Vit Kuban’ <printed>, ‘ HOLOTYPE | Omalium | khmericum sp. n. | Shavrin A. V. des. 2020’ <red, printed> ( NHMB).

Paratypes (47 specimens): 21 ƋƋ, 25 ♀♀ (six specimens dissected): same data as the holotype (5 ƋƋ, 5 ♀♀: CS; 16 ƋƋ, 20 ♀♀: CA); 1 ♀: ‘LAOS—Xieng Khouang, | 30 km NE Phonsavan, | Phou Sane Mt., 19°38.2’N, | 103°20.2’E, 1420 m, 10– | 30. V.2009, leg. Hauck’ <printed>, ‘ Omalium | sp. ♀ | det. V. Assing 2020’ <printed> ( CA). All paratypes with red rectangular printed label: ‘ PARATYPE | Omalium | khmericum sp.n. | Shavrin A. V. des. 2020’.

Description. Measurements (n=40): HW: 0.35–0.46; HL: 0.26–0.33; AL (holotype): 0.61; OL: 0.12–0.15; TM: 0.03–0.06; PL: 0.31–0.39; PW: 0.44–0.57; ESL: 0.51–0.63; EW: 0.60–0.74; AW: 0.51–0.67; MTbL(holotype): 0.36; MTrL(holotype): 0.18 (MTrL 1–4: 0.06; MTrL 5: 0.12); AedL: 0.36–0.41; TL: 2.02–2.98 (holotype: 2.55).

Body and antennae brown, sometimes with paler laterobasal and basal portions of pronotum, elytra, and intersegmental membranes between abdominal tergites; mouthparts and legs yellow-brown. Head with very dense, moderately large and deep punctation, denser in middle and on infraorbital ridges, and finer and coarser between ocelli; neck with dense punctation, finer and sparser in medioapical portion; punctation of pronotum distinctly denser and deeper than that on head, sparser in mediobasal third and lateral portions, with interstices between punctures in middle as broad as diameter of nearest puncture; scutellum without punctures; punctation of elytra dense, deep, punctures slightly finer than that on pronotum and sparser in middle portion along suture, coarser and denser on parascutellar portion; abdomen without visible punctures. Head, pronotum, and elytra without microsculpture, except for posterior portions of infraorbital ridges with transverse and diagonal elevations between punctures; scutellum with very coarse and dense isodiametric microsculpture; abdomen with distinct, dense isodiametric microreticulation.

Head distinctly convex in middle, 1.3 times as broad as long, with wide, moderately long, diagonal impressions on lateral sides of clypeus, sub-antennal impression relatively wide; temples moderately long, distinctly more than twice as long as longitudinal length of eyes; temporal angles rounded; anteocellar foveae very deep, linear, long, reaching level of apical third of eyes; each lateroapical portion with two moderately long ridges extending from above antennal insertion to level of apical third 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 about three times as long as, and slightly broader than the very short preapical segment. Antennae reaching basal third of pronotum when reclined; antennomeres 8–10 distinctly transverse; basal antennomere long, more than two and a half times as long as wide, antennomere 2 suboval, slightly narrower than basal antennomere, 3 narrow, about as long as 2, 4 small, about as long as wide, 5–6 subquadrate, slightly broader than 4, 7 slightly transverse and markedly broader than 6, 8 slightly longer and broader than 7, 9–10 broader than 8, apical antennomere 1.3 times as long as 10, from middle gradually narrowing toward rounded apex.

Pronotum 1.4 times as broad as long, 1.2 times as broad as head, widest in or slightly before middle, gradually narrowing towards the rounded anterior angles and relatively sharply narrowing towards the acute or obtuse posterior angles; laterobasal margins in front of posterior angles slightly concave; anterior margin straight or slightly and widely concave, about as long as posterior margin; lateral margins with traces of fine, indistinct crenulation; paramedian impressions distinct, wide, some paratypes with narrow, short additional impression in medioapical third between paramedian impressions; lateral impressions deep and moderately wide.

Elytra slightly broader than long, 1.6 times as long as pronotum, more or less parallel-sided; posterior margin straight.

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

Abdomen distinctly narrower than elytra, with two small, round or slightly transverse wing-folding patches in middle of abdominal tergite IV, with distinct palisade fringe at apical margin of abdominal tergite VII.

Male. Posterior margin of abdominal tergite VIII widely rounded ( Fig. 46 ). Posterior margin of abdominal sternite VIII deeply concave ( Fig. 47 ). Aedeagus with wide basal portion, gradually narrowed towards the wide, elongate median lobe, with rounded apex ( Figs. 43, 45 ); parameres moderately narrow, simple, very short, slightly extending beyond middle of median lobe, with three very long apical and one short setae; internal sac wide and rather short, with two large, elongate, sclerotized sclerites in middle and field of large spines in medio-apical portion. Aedeagus laterally as in Fig. 44 .

Female. Posterior margin of abdominal tergite VIII straight ( Fig. 48 ). Posterior margin of abdominal sternite VIII slightly concave ( Fig. 49 ). Female accessory sclerite as in Fig. 50 . Spermatheca not found.

Comparative notes. The new species belongs to the oxyacanthae group of the genus as defined by Zanetti (1987): “Median lobe of the aedeagus short, diamond-shaped, much narrower than basal bulb. Parameres simple, not enlarged at apex, with apical setae very long. Tentorial impressions linear”. Regarding the coloration and the general shapes of the body and the aedeagus, O. khmericum sp.n. is similar to O. parallelicolle Coiffait, 1982 from Nepal ( Coiffait 1982), from which it is distinguished by smaller body size, a wider median lobe of the aedeagus, and narrower and shorter parameres.

Distribution. The new species is known from two localities in Phu Phan mountain range, northern Laos.

Bionomics. The specimens were collected on the wing, most likely with a Malaise trap, at elevations of 1420 to 1750 m a.s.l.

Etymology. The specific epithet (adjective) refers to the Khmer people, an ethnic group in Southeast Asia, including Laos.

Figures

FIGURES 43–45. Aedeagus of Omalium khmericum (paratypes): 43, 45—parameral view, 44—lateral view. Scale bar: 0.1 mm.

FIGURES 46–50. Abdominal segments of Omalium khmericum: 46—male tergite VIII (dorsal view), 47—male sternite VIII (ventral view), 48—female tergite VIII (dorsal view), 49—female sternite VIII (ventral view), 50—female accessory sclerite. Scale bar: 0.1 mm.