Geodromicus subquadratus Cheng, Shavrin & Peng, 2020

Cheng, Zhi-Fei, Shavrin, Alexey V. & Peng, Zhong, 2020, New species and records of Geodromicus Redtenbacher, 1857 from China (Coleoptera: Staphylinidae: Omaliinae: Anthophagini), Zootaxa 4789 (1), pp. 132-170 : 162-164

Geodromicus subquadratus Cheng, Shavrin & Peng , sp. n.

( Figs. 41 , 95 , 97–101 , 113 )

Type material examined: Holotype ♂: ‘ China: Xizang, Linzhi City, Bayi District, near Chongzhe Village, 29°34′31″N, 94°23′01″E, 3,230 m a.s.l., mixed leaf litter, sifted, 03.VII.2018, Cheng, Peng & Shen leg.’ <white rectangular label, printed>, ‘ HOLOTYPE | Geodromicus | subquadratus sp. n. | Cheng, Shavrin & Peng des. 2019’ <red rectangular label, printed> ( SNUC).

Paratypes (3 ♂, 2 ♀♀): 2 ♂♂ [two specimens dissected]: same data as the holotype ( SNUC); 1 ♂ [dissected], 2 ♀♀: ‘E Tibet, road Rawu–Baxoi | pass 10 km N Rawu | 29°38’N, 96°43’E, 4,300m | alpine meadow, 12.VII.1997 | Jaroslav Turna leg.’ (1 ♂: CS, 2 ♀♀: CSC). All paratypes with additional red rectangular printed label: ‘ PARATYPE | Geodromicus | subquadratus sp. n. | Cheng, Shavrin & Peng des. 2019’ <red rectangular label, printed>.

Description. Measurements (min-max; n=6): HW: 1.06–1.22; HL: 0.83–1.00; OL: 0.27–0.30; LT: 0.08–0.15; AL (holotype): 3.40; PL: 0.92–1.11; PWmax: 1.35–1.56; PWmin: 1.25–1.39; ESL: 1.93–2.17; EW: 2.17–2.44; MTbL (holotype): 1.57; MTrL (holotype): 0.72 (MTrL 1–4: 0.40; MTrL 5: 0.32; AW: 2.17–2.72; AedL: 1.40–1.50; BL: 5.26–6.84.

Body, maxillary segments 2–3 and antennomeres 1–6 brown to black (elytra sometimes slightly paler); antennomeres 7–11 and legs yellow-brown; mouthparts, apical maxillary segment, basal portions of antennomeres 1–4, basal and apical portions of tibiae and tarsi yellow to reddish-yellow. Body glossy, without microsculpture on elytra; head with distinct, irregular microreticulation, dense and isodiametric between antennal insertion, sometimes indistinct in interocellar depression, and very dense, somewhat rugose and isodiametric on infraorbital ridges; neck with large cellular sculpture; pronotum with irregular isodiametric sculpture, usually indistinct in middle portion; median part of scutellum with distinct fine transverse microreticulation; abdominal tergites with very dense isodimetric microsculpture, slightly denser and more rugose on tergites IV–V. Habitus as in Fig. 95 .

Head 1.2 times as wide as long, slightly convex between anteromedian depression and in portions between ocelli and eyes; frontal portion with slightly elevated supra-antennal protuberance, with deep and wide anteromedian U-shaped depression, sometimes slightly narrowed basad; interocellar depression markedly wide and deep, separated from infraorbital ridges by moderately deep and very long convergent grooves in front of ocelli, almost reaching level of apical margins of eyes; temples about one-third as long as longitudinal length of eyes. Eyes large, convex. Ocelli small, distance between ocelli about 1.2 times as long as distance between ocellus and posterior margin of eyes. Punctation irregular and fine, rather smooth, sparse and indistinct in interocellar depression, punctation of infraorbital ridges denser and somewhat coarser. Neck with sparse and fine punctures. Maxillary palpomere 3 as long as preceding segment, markedly widened apicad; apical palpomere 0.6 times as long as preapical segment, widest in middle, gradually narrowed apicad. Antennae very long, almost exceeding apical margin of elytra when reclined; lengths × widths of antennomeres (holotype): 1: 0.28 × 0.15; 2: 0.21 × 0.12; 3–4: 0.27 × 0.12; 5–6: 0.32 × 0.12; 7–9: 0.33 × 0.12; 10: 0.30 × 0.12; 11: 0.44 × 0.12.

Pronotum slightly convex, 1.4 times as wide as long, 1.2 times as wide as head, widest in anterior third, distinctly more narrowed posteriad than anteriad, with anterior angles rounded and slightly protruded anteriad; narrow basal part of pronotum parallel-sided, not concaved on lateral margins, with obtuse posterior angles; anterior and posterior margins straight; median portion without longitudinal impression, with oval mediobasal impression, indistinct in some paratypes. Punctation very dense, moderately large and deep, usually sparser and smaller in middle, sometimes with narrow impunctated mediobasal area in some paratypes.

Scutellum large, triangular, with several fine punctures in middle.

Elytra slightly convex, 1.1 times as wide as long, twice longer than pronotum, markedly widened posteriad; lateral margins rather broadly flattened; hind margins rounded, truncated at suture. Punctation denser and deeper than that of pronotum, with interstices between punctures about as broad as combined diameters of two nearest punctures, punctures markedly finer in prescutellar portion.

Metatarsus more than half as long as metatibia; apical tarsomere distinctly shorter than the combined length of preceding four tarsomeres.

Abdomen about as wide or slightly wider than elytra, with two large, transverse tomentose spots in the middle of abdominal tergite IV, and smaller two spots in the middle of tergite V, indistinct in some paratypes. Punctation regular, dense and fine .

Male. Protarsomeres 1–4 wide. Apical margins of abdominal tergite VIII ( Fig. 97 ) slightly and sternite VIII ( Fig. 98 ) deeply sinuate. Aedeagus ( Figs. 99, 101 ) with small basal portion rotated inside abdomen in lateral position (90°, when viewed dorsally), long median lobe, gradually widened toward apical third and moderately sharply narrowed toward apex; parameres narrow, long, slightly not extending apex of median lobe, with four moderately short apical setae; internal sac weakly sclerotized, with parallel elongate structures in middle and very long flagellum, coiled in basal part of aedeagus. Lateral aspect of aedeagus as in Fig. 100 .

Female. Protarsomeres 1–4 moderately narrow. Apical margins of abdominal tergite VIII and sternite VIII straight or slightly rounded.

Comparative notes. Based on the shapes of the body and pronotum (with slightly protruded anterior angles), and the general shape of the aedeagus, G. subquadratus sp. n. belongs to the crassipalpis group (Shavrin 2019). Based on the body size and coloration, it is most similar to G. amplissimus Shavrin, 2019 from Sichuan, from which it can be distinguished by a somewhat narrower pronotum, shorter elytra, as well as by the morphology of the aedeagus (median lobe narrower, the shape of the apical portion different), parameres shorter, without additional short setae along entire length of inner edge.

Distribution. The species is known from two localities in Xizang Autonomous Region in China ( Fig. 113 ).

Bionomics. The specimens were collected at elevations from 3230 to 4300 m a.s.l. They were taken by sifting mixed leaf litter near a stream (locality near Chongzhe Village: Fig. 41 ) and from under stones near a stream in an alpine meadow.

Etymology. The specific epithet is the Latin adjective subquadratus (subsquare). It refers to the shape of the pronotum of this species.

Figures

FIGURE 113. Distribution of 21 species of Geodromicus in China: 1–G. abdominalis, 2–G. amplissimus, 3–G. aokii, 4–G. beibienkoi, 5–G. chinensis, 6–G. cupreostigma, 7–G. formosanus, 8–G. frigidus, 9–G. hammondi, 10–G. lestevoides, 11–G. magnus sp. n., 12–G. namucuoicus sp. n., 13–G. ohkurai, 14–G. philydroides, 15–G. shii sp. n., 16–G. sibiricus, 17–G. sinuatocollis, 18–G. sinuatus, 19–G. smetanai, 20–G. subquadratus sp. n., 21–G. taiwanensis.

FIGURES 40–41. Habitus of Geodromicus lucidus (Zhejiang) (Fig. 40) and type locality of G. subquadratus sp. n. in Chongzhe Village, Xizang, China (Fig. 41) (photograph: Zhi-Fei Cheng). Scale bar: 2.0 mm.

FIGURES 95–96. Habitus of species of Geodromicus: 95–G. subquadratus sp. n. (holotype), 96–G. szechwanensis (Shaanxi). Scale bar: 2.0 mm.

FIGURES 97–101. Male of Geodromicus subquadratus sp. n. (paratype): 97–abdominal tergite VIII, 98–abdominal sternite VIII, 99–aedeagus, dorsal view, 100–aedeagus, lateral view, 101–aedeagus, parameral view. Scale bar: 0.2 mm.