Trichodromeus sp.

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 : 30-36

Trichodromeus sp.

Material examined. INDIA: UTTARAKHAND: 1 ♀: ‘SYNTYPE’, ‘ Laptel, N. Kumaon, India 15,000 ft. H. G.C. ’, ‘ Hygrogeus cyanipennis, Cam. v. atrocaeruleus, Ch. ’ ( BMNH) .

Remarks. This specimen was included in the type series of Hygrogeus cyanipennis v. atrocaeruleus (see below). Based on the shape of the habitus and proportions of the maxillary palpomeres 3 and 4, the specimen belongs to an unnamed species of the genus Trichodromeus .

Genus Asiageodromicus gen. n.

( Figs 66–89 )

Type species: Geodromicus crassipalpis Champion, 1920 .

Description. Body medium-sized to relatively large (4.00– 7.95 mm), convex. Coloration brown to black. Punctation of forebody dense and large, finer and sparser on head; abdomen with fine and dense punctation. Body glossy; head, pronotum and abdomen with distinct isodiametric or transverse microsculpture. Pubescence of forebody semierect, moderately dense, longer in apical part of head; abdominal tergites with dense, fine adjoining pubescence.

Head transverse, with distinctly elevated supra-antennal prominences, middle and infraorbital portions; anteriomedian depression wide and deep; interocellar depression wide, moderately deep, separated from infraorbital portions by distinct narrow anteocellar foveae, slightly or strongly convergent anteriad. Temples convex, shorter than longitudinal length of eyes. Eyes relatively small or large, convex. Ocelli small and sometimes indistinct, or moderately large. Gular sutures narrowly separated at level of temples, gradually divergent posteriorly towards base of head ( Fig. 72 ). Labrum strongly transverse, with widely rounded and latero-apical portions strongly protruded apicad, with widely concave apical margin and wide, elongate laterobasal projections ( Fig. 68 ). Mandibles with wide basal part; apical part strongly elongate, with subacute apex; inner margins with two elongate large teeth, rounded apically, slightly shorter in right mandible ( Fig. 69 ). Mentum moderately small, narrow and subtrapezoidal ( Fig. 71 ). Labium moderately narrow, with elongate labial palpomeres; preapical (3) labial palpomere slightly longer and distinctly broader than palpomere 2; apical palpomere slightly longer and narrower than preapical segment; glossa moderately wide ( Fig. 71 ). Maxilla with elongate maxillary palpomeres 2–4, with preapical palpomere broadened apicad, covered with dense pubescence; last maxillary palpomere disitnctly shorter and narrower than penultimate segment, from widest base slightly narrowed toward small rounded apex; galea elongate, distinctly longer than lacinia; lacinia relatively narrow, with narrow and slightly curved apex and several elongate teeth along medial margin ( Fig. 70 ). Antenna long, reaching level of posterior third or apical margin of elytra when reclined, with elongate antennomeres; basal antennomere about or more than three times as long as broad.

Pronotum transverse, widest in anterior portion, gradually or strongly narrowed posteriad, with anterior angles not or distinctly and sometimes strongly protruded anteriad, with moderately short or elongate narrowest basal margins; middle portion without longitudinal depression; lateral portions narrowly bordered, impressed, with wide and deep laterobasal depressions. Prothorax with narrow prosternum and relatively short elongate intercoxal process; pronotal epipleura moderately broad; prosternal processes broadened, subtriangular, each with obtuse apex ( Fig. 73 ). Mesoventrite transverse, with short intercoxal process not reaching apex of middle of mesocoxae ( Fig. 74 ). Scutellum large, with wide and protruded apical portion, widely rounded apically ( Fig. 77 ). Metaventrite moderately wide, with very deep interocoxal cavities and narrow anterior intercoxal process ( Fig. 75 ). Metendosternite as in Fig. 76 .

Elytra slightly broader than long, usually more than twice longer than pronotum, reaching apical margins of abdominal tergite III or IV, with lateral margins widely impressed; elytral epipleura narrow ( Fig. 78 ). Hind wings fully developed.

Legs long and slender; tibiae slightly broadened toward apex, covered with dense and relatively short setae, with additional strong spines in apical portions; males with slightly broadened femora and protarsomeres 1–4.

Abdomen slightly narrower than elytra, with two large transverse tomentose spots in middle of abdominal tergite IV and sometimes with additional small oval spots in middle of tergite V, with narrow palisade fringe on apical margin of abdominal tergite VII.

Male. Aedeagus rotated 90° inside abdomen in lateral position (if viewed dorsally), elongate, with small basal portion and broadened median lobe; parameres narrow and long, slightly shorter or longer than apex of median lobe; internal sac without sclerotized structures, with long flagellum, spirally folded in basal portion ( Figs 79, 81 ). Genital segment as in Fig. 85 .

Female. Gonocoxites narrow, strongly elongate; styli narow, elongate, each with moderately long apical seta ( Fig. 88 ).

Natural History. The species of Asiageodromicus inhabit banks of streams, rivers and lakes under stones and debris, and also can be sifted from mixed leaf litter, mosses and gravel near rivers. Specimens were collected at elevations from 500 to 4718 m a.s.l. from April to August.

Distribution. Species of Asiageodromicus are distributed in the eastern Palaearctic Region, and known from Afghanistan to Nepal and Tibet. Distribution of the Himalayan species as in Fig. 89 .

Etymology. The name of the new genus is a combination of the prefix Asia - and generic name Geodromicus .

Remarks. Shavrin (2019) established the crassipalpis group of the genus Geodromicus for three species from India, Nepal and China. Based on the details of the internal structure of the aedeagus it was compared with the eastern Palaearctic lestevoides group (Shavrin 2018), and was mentioned that from other species of Geodromicus it differs by the shape of the pronotum with anterior angles protruded anteriad. Cheng et al. (2020) provided descriptions of two species from Tibet which were compared with species of the crassipalpis group. During additional morphological studies of species of this group and related genera, I decide to move all these species to a new genus.

Based on the general shapes of the mouthparts (except the shape of the labrum) and the body, Asiageodromicus gen. n. is more similar to the genus Geodromicus . It can be distinguished from it by the combination of the following morphological features: 1) the shape of the apical portion of the labrum with more protruded latero-apical portions and deeper apical emargination ( Fig. 68 ), 2) longer and narrower antennomeres 3–10, 3) more transverse pronotum ( Fig. 73 ), widest in anterior portion, with distinct microsculpture and anterior angles protruded anteriad in some species (anterior angles of Geodromicus not protruded anteriad), 4) the presence of additional small oval spots in the middle of the abdominal tergite V in some species, 5) the position of the aedeagus rotated inside the abdomen in lateral position (90°), 6) the shape of the aedeagus, with small basal portion and broadened median lobe ( Figs 79, 81 ), 7) the lack of sclerotized structures of the internal sac, 8) the shape of longer gonocoxites of the female genital segment ( Fig. 88 ). Also see the key to genera above.

A similar position of the aedeagus was also found in species of Philydrodes ( Shavrin 2017) , Hygrodromicus ( Zerche 1992) and Microhygrodromicus gen. n. (see below).

Key to species of Asiageodromicus

1 Anterior angles of pronotum not or indistinctly protruded anteriad............................................... 2

- Anterior angles of pronotum distinctly protruded anteriad..................................................... 4

2 Pronotum from widest part slightly narrowed posteriad. Elytra indistinctly broader than long. Median lobe moderately narrow (fig. 61 in Cheng et al. (2020)). Body reddish-brown to brown. Habitus as in fig. 57 in Cheng et al. (2020). Body length: 5.34–5.50 mm. China.......................................................................... namucoicus

- Pronotum from widest part strongly narrowed posteriad. Elytra significantly broader than long. Median lobe broadened. Body black............................................................................................... 3

3 Parameres distinctly longer than apex of median lobe, with broadened apical parts (fig. 5I in Coiffait (1977)). Body smaller: 4.00– 4.70 mm. Nepal............................................................................. palpalis

- Parameres shorter than apex of median lobe, with narrow apical part (fig. 4B in Coiffait (1979)). Body larger: 7.00– 7.50 mm. Afghanistan................................................................................ trapezipennis

4 Pronotum moderately small, from widest part strongly narrowed posteriad, with strongly elongate narrowest basal part. Aedeagus as in Fig. 79 . Habitus as in Fig. 67 . Body length: 7.20–7.95 mm. Nepal........................ weiperti sp. n.

- Pronotum larger, from widest part gradually narrowed posteriad, with relatively short narrowest basal part.............. 5

5 Pronotum slightly broader than long. Elytra slightly less than twice as long as pronotum. Aedeagus as in Fig. 81 . Habitus as in Fig. 66 . Body brown, with slightly paler elytra. Body smaller: 4.90 mm. Nepal............................. dolpoensis

- Pronotum significantly broader than long. Elytra distinctly more than twice as long as pronotum. Coloration different. Body larger............................................................................................... 6

6 Body dark brown, with reddish-brown elytra. Aedeagus as in Fig. 6 (Shavrin (2019)). Habitus as in fig. 3 (Shavrin (2019)). Body length: 5.87–7.30 mm. Nepal................................................................ spadiceus

- Body brown to black.................................................................................. 7

7 Median lobe narrow (fig. 4 in Shavrin (2019)). Habitus as in Fig. 1 (Shavrin (2019)). Body length: 5.20–7.35 mm. India, Nepal...................................................................................... crassipalpis

- Median lobe wide..................................................................................... 8

8 Pronotum broader, 1.6 times as broad as long. Parameres longer than apex of median lobe (fig. 8 in Shavrin (2019)). Habitus as in fig. 2 ( Shavrin (2019)). Body length: 5.55–7.50 mm. China (Sichuan, Yunnan).......................... amplissimus

- Pronotum slightly narrower, 1.4 times as broad as long. Parameres shorter than apex of median lobe (figs 99. 101 in Cheng et al. (2020)). Habitus as in fig. 95 ( Cheng et al. (2020)). Body length: 5.26–6.84 mm. China (Xizang)......... subquadratus

Species list

Figures

FIGURE 89. Distribution of Asiageodromicus in the Himalayan Region: A. crassipalpis (circles), A. dolpoensis (star), A. palpalis (Coiffait, 1977) (squares), A. spadiceus (triangles), A. weiperti sp. n. (diamonds)

FIGURES 66–67. Habitus of Asiageodromicus: 66—A. dolpoensis (holotype), 67—A. weiperti (paratype). Scale bar: 1.0 mm.

FIGURES 68–78. Asiageodromicus crassipalpis: 68—labrum (dorsal view), 69—mandibles (left and right, dorsal view), 70—maxilla (dorsal view), 71—labium and mentum (ventral view), 72—head (ventral view), 73—prothorax (ventral view), 74—mesoventrite (ventral view), 75—metaventrite (ventral view), 76—metendosternite (dorsal view), 77—scutellum (ventral view), 78—elytron (ventral view). Scale bar: 0.1 mm.

FIGURES 79–88. Aedeagus (Figs 79–82) and abdominal segments (Figs 83–88) of Asiageodromicus (Figs 79–80: A. weiperti (holotype); Figs 81–82; A. dolpoensis (holotype); Figs 83–88: A. crassipalpis): 79, 81—aedeagus, parameral view, 80, 82— aedeagus, lateral view, 83—male tergite VIII, 84—male sternite VIII, 85—male genital segment, 86—female tergite VIII, 87—female sternite VIII, 88—female genital segment. Scale bar: 0.1 mm.

FIGURES 1–6. Habitus of Hygrogeus (Fig. 1) and Trichodromeus (Figs 2–6): 1—H. aemulus (Tirol), 2—T. armatus (Kashmir: Baltal), 3—T. armatus (Kashmir: Kolahoi Glacier), 4—T. ketmeniensis (Kyrgyzstan: Chatkal Mts.), 5—T. ovchinnikovi (holotype), 6—T. kumaonensis (paratype). Scale bar: 1.0 mm.