Xiangxius jiangi Tian & X. Huang, 2021

Tian, Mingyi, Huang, Xinglong & Li, Chenliang, 2021, Contribution to the knowledge of subterranean ground beetles from eastern Wuling Mountains, China (Coleoptera: Carabidae: Trechinae), Zootaxa 4926 (4), pp. 521-534 : 523-526

Xiangxius jiangi Tian & X. Huang , n. sp.

( Figs. 1–4 )

Type material. Holotype male, paratypes 1 male and 1 female, cave Tangle Dong, suburb of Jishou , Xiangxi Tujia & Miao Autonomous Prefecture, western Hunan Province, 28°18’21”N / 109°39’15”E, 270 m in altitude, 2018-I- 15, leg. Xinglong Huang, in SCAU.

Diagnosis. A medium-sized aphaenopsian trechine species, with a distinctly elongated body and thin appendages, without eyes and lacking pigmentation, elytra with striking humeral angles and well-marked setiferous pores.

Description. Length: 6.0– 6.6 mm, width: 1.7–1.9 mm. Habitus as in Fig. 2 .

Body yellowish-brown, antennae, palps and tarsi yellow; head covered with a few setae, pronotum and elytra smooth and glabrous, moderately shining, underside of head with denser setae than on upper side, ventral thorax with several setae, abdominal ventrites shortly and densely pubescent. Moderately shining. Microsculpture: transverse meshes on head, striate on pronotum and elytra.

Head ( Fig. 2 , 3A ) much longer than wide, HLm/HW = 2.4–2.5, HLl/HW = 1.7–1.9; genae slightly expanded, widest at about middle of head excluding mandibles; front moderately, and vertex strongly convex; frontal furrows nearly parallel-sided; anterior and posterior supraorbital pores located at middle and close to neck constriction, respectively; clypeus 6-setose; labrum transverse, frontal margin almost straight, 6-setose; mentum bisetose on either side of tooth base, tooth moderately long, bifid at tip; ligula thick and short, 8-setose at apex, inner two much longer than others; palps thin and elongate, all glabrous but bisetose on inner margin of 2 nd labial palpomere which is 1.2 times as long as 3 rd; 3 rd maxillary palpomere 1.2 times as long as 4 th; suborbital pores close to neck constriction; antennae pubescent from 2 nd– 11 th, 1 st antennomere stouter and shorter than other joints, relative length of each antennomere in the holotype specimen as: the 1 st (1.0), 2 nd (1.2), 3 rd (1.9), 4 th (1.6), 5 th (1.7), 6 th (1.9), 7 th (1.7), 8 th (1.5), 9 th (1.4), 10 th (1.3) and 11 th (1.6).

Prothorax ( Fig. 2 ) distinctly tumid at sides, PrW/PnW = 1.1–1.2, widest at about basal 1/3; pronotum much longer than wide, PnL /PnW = 1.6–1.7, as long as head excluding mandibles, as wide as head; lateral margins finely bordered throughout, widest at about middle, gently contracted forwards and backwards, slightly sinuate before hind angles which is more or less bluntly rectangular, base and front nearly straight, unbordered, subequal in width; anterior and posterior latero-marginal setae at 5/6 from base and just before hind angles respectively; disc convex, median finely depressed along mid-line; both of fore and basal transversal impressions well-marked, basal foveae shallow. Scutellum quite large.

Elytra ( Fig. 2 , 3B ) slightly longer than fore body including mandibles, much longer than wide, EL/EW = 1.8–1.9, twice as wide as prothorax; base unbordered, lateral margins not serrate either ciliate, nearly obliquely truncate at prehumeral portions, widest at about middle of elytra; basal pore present at sides of scutellum, anterior and posterior dorsal pores on the 3 rd stria at basal 1/4 and apical 3/7 of elytra respectively; in marginal umbilicate pores, only 2 nd pores close to marginal gutter, 1 st pore closer to 3 rd than to 4 th present, distance from 5 th pore to 4 th slightly shorter than that to 6 th.

Legs densely pubescent; 1 st protarsomere distinctly widened in male, shortly and bluntly denticulate at inner apex; 1 st tarsomere much shorter than 2 nd– 4 th combined in fore legs, whereas as long as in middle and hind legs; tibiae without longitudinal sulci.

Male genitalia ( Fig. 4 ): The median lobe of aedeagus medium-sized for cave trechines, quite elongate, gently arcuate towards apex which is obtuse and blunt; basal opening quite small, with a large and almost rounded sagittal aileron; inner sac armed with a long copulatory piece, which is about 1/4 as long as aedeagus; in dorsal view, apical lobe thin, much longer than wide, gently contracted towards apex; parameres well-developed, widened in apical portions, each with four long setae at apex.

Etymology. Dedicated to Mr. Rixin Jiang, a young and active beetle expert in Qingdao University of Science and Technology, Shandong Province.

Distribution. China (Hunan). Known only from the limestone cave Tangle Dong, sympatric with the following species, Guizhaphaenopsodes solidior n. gen, n. sp. ( Fig. 1 ).

Tangle Dong, also called Xiaotaohuayuan Dong, is located at about 10 km west of Jishou, the capital city of Xiangxi Tujia & Miao Autonomous Prefecture, western Hunan. The galleries are composed of three layers and three entrances, with a total length of about 2500 m. All beetles were collected in dark zones of different places in the second layer, several hundred metres from the main entrance.

Figures

FIGURE 1. A distribution map showing the locality caves of the three new species described in the present paper (Tangle Dong: Xiangxius jiangi Tian & X. Huang, n. gen., n. sp. and Guizhaphaenopsodes solidior Tian & X. Huang, n. gen., n. sp.; Qizimei Dong: Sinotroglodytes hefengensis Tian & Li, n. sp.).

FIGURE 2. Xiangxius jiangi Tian & X. Huang, n. gen., n. sp., habitus

FIGURE 3. Ventral head (A) and elytral chaetotaxy (B) of Xiangxius jiangi Tian & X. Huang, n. gen., n. sp.

FIGURE 4. Male genitalia of Xiangxius jiangi Tian & X. Huang, n. gen., n. sp. (A. median lobe and parameres, lateral view; B. apical lobe of median lobe, dorsal view)