Hygrodromicus carbonarius Cheng, Li & Peng, 2021

Cheng, Zhi-Fei, Pan, Zhao-Hui, Li, Li-Zhen & Peng, Zhong, 2021, Three new species of Hygrodromicus Tronquet, 1981 (Coleoptera: Staphylinidae Omaliinae: Anthophagini) from China, Zootaxa 4963 (1), pp. 138-148 : 139-142

Hygrodromicus carbonarius Cheng, Li & Peng , sp. n.

( Figs 1–2 , 7 , 8B )

Type material (3 ♂♂, 6 ♀♀). Holotype: ♂, ‘ China: Xizang, Linzhi City, Gongbujiangda County [工布江ffi县], near Gaduogang Village [ḋľÑ村], 29°53′60″N, 93°14′22″E, alt. 3620 m, 18.vii.2018, Cheng, Peng & Shen leg. / HOLOTYPE <red rectangular label, printed> ♂, H. carbonarius sp. n., det. Cheng, Li & Peng, 2021, SNUC’ ( SNUC) . Paratypes: 1 ♂, 6 ♀♀, same data as the holotype ( SNUC) ; 1 ♂, ‘ China: Yunnan Prov., Fugong, Lishadi Town, 8.5 km up Shibali , riverside, 27.18408°N, 98.71882°E, 3095 m, 2005.VIII.8 day, Liang H.B., Zhang J.F. California Academy & IOZ., Chinese. Acad. Sci. ’ ( SNUC) ; All paratypes with label : ‘ PARATYPE <yellow rectan- gular, printed> ♂ [or ♀], H. carbonarius sp. n., det. Cheng, Li & Peng, 2021, SNUC’.

Description. Measurements (in mm) and ratios: BL 4.45–5.95; FL 2.84‒3.56; HL 0.61–0.89; HW 0.83–0.95; PL 0.78–1.17; PWb 0.83–1.00; PWm 0.83‒1.17; EL 1.28–1.72; EW 1.45‒2.06; AnL 2.71‒3.41; AeL 0.93‒0.99; HL/HW 0.69–0.94; PL/PWm 0.76‒0.84; EL/EW 0.79–0.90.

Body ( Fig. 1A ) broad, black, antennae paler, basal portions of femora, apical portions of tibiae and tarsi reddishbrown.

Head ( Fig. 1B ) subtriangular and transverse, broadest at level of eyes; vertex strongly transverse, with deep Ushaped impression between eyes; frons between supra-anternnal tubercles slightly impressed; clypeus short and narrow, weakly convex; eyes moderately prominent, about 1.50 times as long as temples (holotype); ocelli indistinct, distance between ocelli 1.1 times as long as distance between ocellus and posterior margin of eye (holotype). Vertex and frons covered with coarse and dense punctures, and reticular microsculpture. Pubescence on head long, dense and decumbent in anterior portion. Labrum ( Fig. 1D ) subrectangular, with slightly concaved anterior margin. Mandibles ( Figs 1E–F ) subtriangular, each with broad base, and curved distal tooth; right mandible armed with a small distinct subtriangular tooth on inner margin near middle; prostheca with short and dense pubescence from base to above middle of mandible. Maxilla ( Fig. 1G ) with smooth subtriangular stipes, subrectangular palpifer with long pubescence on external margin, elongate galea with short pubescence, and slender lacinia with dense pubescence and long teeth. Maxillary palpi composed of minute and elongate palpomere 1, slightly curved palpomere 2, broadened palpomere 3, and short subcylindrical palpomere 4. Labium ( Fig. 1H ) elongate, with flattened prementum divided by longitudinal groove anteriorly. Labial palpi long, palpomere 1 moderately large and elongate; palpomere 2 robust, broadened apically; palpomere 3 slender, distinctly narrower than palpomere 2. Antennae ( Fig 1C ) with long antennomeres; length × width (in mm) of antennomeres 1–11 (holotype): 0.26 × 0.13: 0.15 × 0.11: 0.19 × 0.11: 0.21 × 0.11: 0.22 × 0.11: 0.22 × 0.11: 0.25 × 0.11: 0.25 × 0.11: 0.25 × 0.11: 0.22 × 0.11: 0.34 × 0.11.

Pronotum subtrapezoidal, broadest near anterior fourth; anterior margin widely rounded, lateral margins in anterior 2/3 rounded and nearly straight at posterior third, basal margin straight; hind angles obtuse; disc distinctly convex, with indistinct impression, stretching from middle to base. Punctures of disc finer and denser than those of head; pubescence moderately long, dense and decumbent in posterior portion; microsculpture distinct and evenly distributed. Scutellum triangular, covered with several punctures and pubescence, and distinct microsculpture.

Elytra subtrapezoidal, short, distinctly wider than long, gradually dilated posteriorly, posterior angles broadly rounded; punctures and pubescence similar to those of pronotum; microsculpture absent. Hind wings brachypterous, but not completely reduced.

Abdomen distinctly transverse, widest at segment IV, evenly narrowing posteriorly. Tergites with fine punctures and microsculpture, and short decumbent pubescence, denser on apical tergites; tergites IV–V with a pair of tomentose spots in middle, spots on tergite V smaller and less transverse.

Male. Apical margin of abdominal tergite VIII ( Fig. 1I ) somewhat truncated, indistinctly emarginated; apical margin of abdominal sternite VIII ( Fig. 1J ) broadly emarginated. Aedeagus ( Figs 2A–C ) elongate, median lobe slightly emarginated in lateral margins near anterior third; parameres slightly asymmetrical, slender, significantly exceeding apex of median lobe, each bearing four apical setae; internal sac with submedian elongate membranous structures and long flagellum between them.

Female. Apical margin of abdominal sternite VIII without concavity apically.

Comparative notes. Based on the general shape of the forebody, coloration, shapes of maxillary and labial palpi, the presence of U-shaped impression between eyes, and shapes of apical margins of male tergite and sternite VIII, H. carbonarius sp. n. is most similar to H. danlangi sp. n., but differs by the wider pronotum, the presence of additional small tooth in inner margins of mandible, less concaved apical margin of labrum, and details of the internal and external morphology of the aedeagus.

Distribution. Southwestern China: Xizang, Yunnan ( Fig. 7 ).

Bionomics. The species inhabits wet mosses or mixed leaf litter on banks of small streams with very cold water ( Fig. 8B ). Specimens were collected at high elevations more than 3000 m a.s.l. in Xizang in July and in Yunnan in August.

Etymology. The specific epithet ‘ carbonarius ’ means ‘carbon’, referring to the coloration of a new species, black as carbon.

Figures

FIGURE 1. Hygrodromicus carbonarius sp. n., male. Habitus of male in dorsal view (A); head in dorsal view (B); left antenna (C); labrum in dorsal view (D); left maxilla in ventral view (G); right (E) and left (F) mandibles in dorsal view; labium in ventral view (H); abdominal sternite VIII (I) and tergite VIII (J). Scale bar: 2.0 mm in A; 1.0 mm in C; 0.30 mm in B; 0.10 mm in D–J.

FIGURE 2. Aedeagus features of Hygrodromicus carbonarius sp. n.: dorsal view (A), lateral view (B), and ventral view (C). Scale bar: 0.20 mm.

FIGURE 7. Distribution of Chinese species of the genus Hygrodromicus. H. carbonarius sp. n.: red circle; H. danlangi sp. n.: yellow triangles; H. shaanxiensis sp. n.: pink star.

FIGURE 8. Type localities of Chinese species of the genus Hygrodromicus. A Chongzhe village, Bayi District, alt. 3230 m (Hygrodromicus danlangi sp. n.) B Gaduogang village, Gongbujiangda County, alt. 3620 m (Hygrodromicus danlangi sp. n. and Hygrodromicus carbonarius sp. n.)