Himalodromeus reductus, Shavrin, 2024

Shavrin, Alexey V., 2024, Review of Hygrogeus Mulsant & Rey, 1880 and Trichodromeus Luze, 1903, with descriptions of three new genera from the eastern Palaearctic Region (Coleoptera: Staphylinidae: Anthophagini: Omaliinae), Zootaxa 5531 (1), pp. 1-62 : 50-55

Himalodromeus reductus sp. n.

( Figs 94, 97 , 114–115 , 123–124 )

Type material examined. Holotype ♂ (dissected): ‘ NEPAL Karnali /Humla | 20km NW Simikot, 3 km | W Chala 37–4300m HF | 29°59’N, 81°25’E. 24.VI. | 2001 leg. A.Weigel GW’ <printed>, ‘ HOLOTYPE | Himalodromeus | reductus sp. n. | Shavrin A.V. des. 2024’ <red, printed> ( NME).

Paratypes: 3 ♂♂ (dissected), 5 ♀♀: same data as the holotype (2 ♂♂, 1 ♀: cSh, 1 ♂, 4 ♀♀: NME); 1 ♂: ‘ NEPAL Prov. Seti Distr. Bajura | 19kmW Simikot, Kuwadi Khola, | 3500m 29°53’14’’N, 81°38’40’’E | 04.– 05.07.2001 leg. A.Kopetz | riverbank, coniferous-birch forest’ ( NME); 2 ♂♂, 2 ♀♀ (one specimen dissected): ‘ NEPAL, Prov. Karnali | distr.Jumla, N Khari | Lagna, Bachtal, Ufer | 3280mNN; 29°22,14’N | 82°09,17’E; 21.VI.1999 | leg. M. Hartmann’ (1 ♀, 1 ♀: cSh, 1 ♂, 1 ♀: NME); 1 ♀: ‘ NEPAL, Prov. Karnali | Gothichaur, SW, | nördlich Haka-Pass | 3800–4300 m | 7. VI. 2007 | leg.: J. Weipert’ ( NME); 1 ♀: ‘ Nepal, District Karnali, Nähe Pohada 02.06.1997 | 3010– 3400 mNN, leg.Grill, | Flussufer | HF, 29°04’N 82°42’E’ ( NME); 1 ♂ (dissected; left antennomeres 6–11 missing): ‘ NEPAL Karnali zone Khari | Lagna 35–3700m N-Jumla | 23./24.6., 4.7.[19]95 lg. Ahrens | & Pommeranz’ ( NME); 1 ♀: ‘ Nepal, District Jumla, | Lager N Maharigaon, | 07.– 09.07.1997; 3220 mNN, | Wald, Ufer, leg. Grill, HF | 29°20’25’’N, 82°23’16’’E’ ( NME). All paratypes with additional red printed label: ‘ PARATYPE | Himalodromeus | reductus sp. n. | Shavrin A.V. des. 2024’.

Description. Measurements (n=18): HW: 1.35–1.41; HL: 0.89–0.93; OL: 0.29–0.32; TL: 0.24–0.27; AL (holotype): 5.20; PL: 1.60–1.68; PWmax: 2.07–2.12; PWmin: 1.48–1.58; ESL: 2.11–2.16; EW: 2.70–2.86; MTbL (holotype): 2.22; MTrL (holotype): 0.99 (MTrL 1–4: 0.57; MTrL 5: 0.42); AW: 2.50–2.67; AedL: 1.62–1.75; BL: 6.25–8.00 (holotype: 7.05).

Habitus as in Fig. 94 . Body reddish-brown, with paler basal portions of pronotum and elytra; mouthparts, antennae and legs brown (apical maxillary segment and tarsi paler; femora slightly darker). Head with dense and moderately fine isodiametric microsculpture, coarser on apical part of clypeus and in middle, sparser and finer in middle portion at level of anterior margins of eyes; neck with dense transverse and coarse microreticulation; pronotum with fine transverse microsculpture, finer in middle and sometimes without sculpture in mediobasal portion; scutellum with fine and dense transverse sculpture.

Head 1.5 times as broad as long; anterio-median depression wide and deep, sometimes narrowed basad and indistinctly connected with wide and moderately deep subrectangular interocellar depression; anteocellar foveae relatively short, strongly divergent latero-anteriad toward level of middle or anterior third of eyes; basal part of interocellar depression in front of ocelli sometimes with indistinct widely rounded elevation; temples slightly shorter than longitudinal length of eyes. Ocelli small and sometimes indistinct, located at level of posterior margins of eyes or slightly below; distance between ocelli 1.3–1.6 times as long as distance between ocellus and posterior margin of eyes. Punctation moderately fine and dense, sparser in middle; mediobasal portion between ocelli sometimes without visible punctures; neck without or with sparse and fine punctation. Apical maxillary palpomere 1.7 times to twice as long as penultimate segment, gradually broadened toward preapical part, with rounded apex. Antenna reaching posterior third of elytra when reclined; antennomere 3 significantly longer than 2, 4–9 slightly longer than 3, 10 slightly shorter than 9, apical antennomere about as long as 10 or slightly longer.

Pronotum 1.2 times as broad as long, widest in anterior portion, strongly narrowed posteriad toward obtuse or sharp hind angles; frontal part not protruded anteriad, sometimes with slightly concave latero-apical and widely concave apical margins ( Fig. 97 ); laterobasal margins in front of hind angles relatively short, somewhat subparallel; posterior margin widely concave; middle portion of disc without or with distinct narrow longitudinal depression; mediobasal part without or with indistinct shallow and transverse impression; laterobasal portions strongly and widely impressed; lateral margins narrowly bordered, sometimes indistinctly reflexed, with shallow smooth crenulation. Punctation slightly larger and denser than that on head, sparser in middle and/or mediobasal portion; interstices between punctures in middle about as long as diameters of 2–3 nearest punctures. Scutellum without or with several fine punctures.

Elytra 1.2–1.3 times as broad as long, 1.2–1.3 times as long as pronotum, strongly broadened posteriad; lateral portions widely impressed and distinctly reflexed. Punctation dense, larger and deeper than that on pronotum, finer and sparser around scutellum and sometimes sparser along suture.

Abdomen narrower than elytra.

Male. Profemora and protarsomeres 1–4 wide. Pronotum slightly more convex. Posterior margin of abdominal tergite VIII rounded or straight. Posterior margin of abdominal sternite VIII with significant deep emargination, additionally narrowly concave in middle, with long and dense setation on each elongate latero-apical portion ( Fig. 123 ). Aedeagus with significantly widened median lobe, broader in middle than phallobase, from middle sharply narrowed toward subacute apex; parameres narrow and extremely short, with three short apical setae; internal sac with narrow sclerotized structures in about middle, with long flagellum spirally folded in basal portion and distinctly broadened in basal part ( Fig. 114 ). Lateral aspect of the aedeagus as in Fig. 115 .

Female. Profemora and protarsomeres 1–4 moderately narrow. Pronotum less convex. Posterior margin of abdominal tergite VIII straight or rounded. Posterior margin of abdominal sternite VIII straight.

Comparative notes. Himalodromeus reductus sp. n. can be distinguished from the other congeners by the coloration of the body, the shape of the frontal part of the pronotum, which is not protruded anteriad, the significantly broader median lobe, shorter parameres and other details of external and internal morphology of the aedeagus.

Distribution. Himalodromeus reductus sp. n. is known from several localites in western Nepal ( Fig. 124 ).

Bionomics. Specimens were collected at elevations from 3010 to 4300 m a.s.l. Some paratypes were collected in forest zone at river banks.

Etymology. The specific epithet is the Latin adjective reductus , - a, - um (diminished). It alludes to the extremely short parameres.

Genus Microhygrodromicus gen. n.

( Figs 125–141 )

Type species: Microhygrodromicus exiguus sp. n.

Description. Body elongate, convex, small (2.71–3.70 mm), dark-brown, shiny and sometimes with indistinct bronze reflex ( M. exiguus sp. n.). Head with irregular fine or moderately large punctation; punctation of pronotum and elytra markedly denser and larger, punctation of abdomen fine. Head and pronotum with fine transverse microreticulation or without it; abdomen with fine transverse meshes. Pubescence of body dense and semi-erect ( M. exiguus sp. n.), sparser and finer in M. politus sp. n.; abdominal tergites with finer adjoining setation.

Head broader than long, with disitinctly elevated supra-antennal prominences, median part and infraorbital portions; anteriomedian depression wide and moderately deep; interocellar depression narrow and deep, somewhat subtriangular; anteocellar foveae moderately deep and long, slightly convergent latero-anteriad and reaching level of anterior third of eyes. Temples convex, short ( M. politus sp. n.) or elongate and distinctly protruded posteriad ( M. exiguus sp. n.). Eyes large, strongly convex. Ocelli well distinct, large and convex, located markedly below level of posterior margin of eyes. Gular sutures widely separated at level of posterior third of eyes, strongly divergent posteriorly towards base of head. Labrum small, transverse, with widely rounded latero-apical portions and indistinct apical emargination, with moderately wide laterobasal projections ( Fig. 127 ). Mandibles with wide basal and narrow apical portions; apical part elongate and strongly curved; inner margin of preapical portion of each mandible with two large subtriangular teeth, indistinct rounded protrusion in about middle of left mandible and small triangular tooth with rounded apex in right mandible ( Fig. 128 ). Mentum narrow, strongly transverse, with several very long setae on apical margin; labium narrow, with elongate preapical labial palpomere, distinctly longer and slightly broader in apical portion than palpomere 2, last palpomere longer and narrower than palpomere 3; glossa narrow and elongate ( Fig. 130 ). Maxilla as in Fig. 129 ; palpomere 2 of maxillary palpi with elongate and moderately dense setation in preapical portion; preapical palpomere slightly longer and distinctly broader than penultimate segment, covered with dense and moderately long setae; apical palpomere slightly shorter and more than twice narrower than preapical palpomere, from basal margin gradually narrowed toward small rounded apex; galea narrow and slightly longer than apex of lacinia; lacinia narrow, with slightly curved short apex and several elongate teeth along apical part of medial margin. Antenna reaching basal third of elytra when reclined, with shortened antennomeres 3–10.

Pronotum convex, widest in anterior portion, distinctly more narrowed posteriad than anteriad, without or with distinct crenulation ( M. exiguus sp. n.) on slightly bordered lateral margins, without or with depression ( M. politus sp. n.) in mediobasal portion. Prothorax with narrow prosternum, long interocoxal and wide prosternal processes; pronotal epipleura moderately broad. Mesoventrite relatively short, with long intercoxal process reaching middle of mesocoxae. Scutellum large. Metaventrite wide, with deep and broad intercoxal cavities and elongate anterior intercoxal process almost reaching apex of mesoventritall process.

Elytra convex or slightly depressed in middle ( M. politus sp. n.), slightly broader than long, significantly longer than pronotum, slightly broadened posteriad, with widely rounded apical margins; elytral epipleura narrow. Hind wings fully developed.

Legs moderately long and slender; tibiae slightly broadened toward apex, covered with dense elongate setae, denser and stronger along inner margins, without or with rows of additional very small thorns along inner margin in M. politus sp. n.; metatarsus about twice or distinctly more than twice ( M. politus sp. n.) shorter than metatibiae.

Abdomen slightly broader than elytra, with two indistinct or distinct, large and transverse tomentose spots in the middle of abdominal tergite IV; posterior margins of abdominal tergite VII with narrow palisade fringe.

Male. Aedeagus 90° rotated inside abdomen in lateral position (if viewed dorsally), with moderately wide basal and median portions, and apical part widely rounded or distinctly narrowed apically ( M. politus sp. n.), parameres narrow, not reaching apex of median lobe, with four apical setae; internal sac complicated, moderately large, with elongate sclerotized structures in about middle and long narrow flagellum, spirally folded in basal potions ( Figs 131 , 136 ). Genital segment as in Figs 133 , 138 .

Female unknown.

Species included. M. exiguus sp. n., M. politus sp. n.

Natural History. Specimens of the genus were collected in forests from high elevations from 1900 to 3890 m a.s.l.

Distribution. Both new species are known from Yunnan, China ( Fig. 133 ).

Etymology. The generic name is a combination of the Greek word μικρός (little, small) and the existing name Hygrodromicus . It alludes to the similarity of the new genus with it.

Remarks. Based on the general shape of the body and aedeagus, being 90° rotated inside the abdomen in lateral position, Microhygrodromicus gen. n. is more similar to Hygrodromicus , from which it can be distinguished by the significantly smaller body, the shape of the mandibles with narrower apical portion and stronger two preapical teeth on inner margin, the shape of the significantly longer preapical and longer apical maxillary palpomeres ( Fig. 128 ), the longer apical labial palpomere ( Fig. 130 ), significantly shorter antennae with shorter antennomeres 4–10, narrower interocellar depression and longer postocular portions of the head, distinctly narrower pronotum and elytra, and more complicated structure of the internal sac. Based on the small body, general shapes of mandibles and labial palpi, and short antennae with shortened antennomeres 4–10, it somewhat similar to small Himalayan species of the genus Microedus (see Shavrin 2024a), from which can be distiguished by more convex forebody, finer microsculpture of the head and the pronotum, the longer apical maxillary palpomere, deeper and narrower interocellar depression, longer and narrower elytra, and different morphology of the aedeagus. From both genera, Microhygrodromicus can be distinguished by the proportions of two preapical maxillary palpomeres, the shape of an interocellar depression, longer temples, the presence of crenulation on lateral margins of the pronotum ( M. exiguus sp. n.), and details of the morphology of more complicated aedeagus. Also see the key to genera below.

Key to species of Microhygrodromcius

1 Temples slightly shorter than longitudinal length of eyes. Apical part of pronotum moderately narrow; lateral margins slightly crenulate; mediobasal portion without depression. Elytra about twice as long as pronotum. Apical part of median lobe with widely rounded apex ( Fig. 131 ). Habitus as in Fig. 125 . Body smaller: 2.71 mm. China (Yunnan)............ exiguus sp. n.

- Temples twice shorter than longitudinal length of eyes. Apical part of pronotum relatively wide; lateral margins without crenulation; mediobasal portions with oval depression. Elytra distinctly less than twice as long as pronotum. Apical part of median lobe gradually narrowed toward subacute apex ( Fig. 136 ). Habitus as in Fig. 126 . Body larger: 3.70 mm. China (Yunnan)................................................................................... politus sp. n.

Species list

Figures

FIGURE 124. Distribution of Himalodromeus: H. cyanipennis (circles), H. grandis (square), H. reductus (triangles).

FIGURES 90–97. Habitus (Figs 90–94) and apical part of pronotum (Figs 95–97) of Himalodromeus: 90—H. cyanipennis (Uttarakhand), 91, 95—H. cyanipennis (paratype), 92—Hygrogeus cyanipennis var. atrocaeruleus (lectotype), 93, 96—H. grandis (holotype), 94, 97—H. reductus (paratype). Scale bar: 1.0 mm.

FIGURES 110–115. Aedeagus of Himalodromeus (Figs 110–111: H. cyanipennis (paralectotype), Figs 112–113: H. grandis (holotype), Figs 114–115: H. reductus (paratype): 110, 112, 114—parameral view, 111, 113, 115—lateral view. Scale bar: 0.1 mm.

FIGURES 116–123. Abdominal segments (ventral view) of Himalodromeus (Figs 116–121: H. cyanipennis; Fig. 122: H. grandis; Fig. 123: H. reductus): 116—male tergite VIII, 117, 122–123—male sternite VIII, 118—male genital segment, 119— female tergite VIII, 120—female sternite VIII, 121—female genital segment. Scale bar: 0.1 mm.

FIGURES 125–126. Habitus of Microhygrodromicus: 125—M. exiguus (holotype), 126—M. politus (holotype). Scale bar: 1.0 mm.

FIGURES 127–130. Mouthparts of Microhygrodromicus exiguus (holotype): 127—labrum (dorsal view), 128—mandibles (left and right, dorsal view), 129—maxilla (dorsal view), 130—labium (ventral view). Scale bar: 0.1 mm.

FIGURES 131–135. Microhygrodromicus exiguus: 131—aedeagus, parameral view, 132—aedeagus, lateral view, 133—male genital segment, 134—male tergite VIII, 135—male sternite VIII. Scale bars: 0.1 mm.

FIGURES 136–140. Microhygrodromicus politus: 136—aedeagus, parameral view, 137—aedeagus, lateral view, 138—male genital segment, 139—male tergite VIII, 140—male sternite VIII. Scale bars: 0.1 mm.

FIGURE 141. Distribution of Microhygrodromicus exiguus (circle) and M. politus (square) in Yunnan, China.