Libotrechus duanensis Lin and Tian

Lin, Wei & Tian, Mingyi, 2014, Supplemental Notes on the GenusLibotrechusUéno (Coleoptera: Carabidae: Trechinae), with Description of a New Species from Guangxi, Southern China, The Coleopterists Bulletin 68 (3), pp. 429-433 : 430-433

Libotrechus duanensis Lin and Tian , new species ( Figs. 1 − 3 )

Holotype. Male , CHINA: Guangxi Zhuang

Autonomous Region : Du’ an Yao Autonomous Xian : Longfu Xiang : Longfu Cun : Shangmo Tun, a cave named Shuiyuan Dong, 24°11.335′N 107°49.865′E, 509 m, 28 June 2013, Wei Lin leg., deposited in SCAU .

Description. Length 7.0 mm; width 2.3 mm. Habitus as in Fig. 2 . Color brown, except palps, antennae, and tarsi light brown. Head: Subquadrate, longer than wide, HL/HW=1.63, widest at about middle of genae, genae evenly convex with a short setae laterally; ventral side with a pair of suborbital setae; eyes completely absent; frontal furrows subparallel, slightly divergent anteriorly from level of hind margin of antennal insertion; supraorbital areas smooth and glabrous, anterior pair of supraorbital pores present at about middle of genae, distances from supraorbital pore to outer margin of gena and to frontal furrow nearly equal; posterior pair of supraorbital pores absent; neck constriction distinctly defined; clypeus nearly quadrate, quadrisetose; labrum reverse trapezoidal, widely emarginate apically, 6-setose; mandibles moderate in size, feebly hooked at apical parts, right mandible bidentate; mentum and submentum clearly separated by labial suture; mentum bisetose, with 2 small basal pits; mental tooth small, bifid at apex; submentum 6-setose; ligula broad at tip, 8-setose, inner pair much longer than others; palps subcylindrical; penultimate labial palpomere bisetose on inner margin, with 2 additional setae on outer margin, apical palpomere glabrous, 2 nd labial palpomere much longer than 3 rd (about 1.3X); maxillary palps glabrous, 3 rd palpomere longer than 4 th; antennae filiform, rather short, extending to about middle of elytra; 2 nd –11 th antennomeres pubescent; 1 st and 2 nd antennomeres subequal in length, 3 rd about 1.5X longer than 2 nd and slightly longer than 4 th. Pronotum: Subcordate, convex, smooth, and glabrous; wider than head, PL/HL= 1.44, but much narrower than elytra, PL/EL= 0.59; slightly longer than wide, PL/PW=1.14; widest at about apical 1/3; sides distinctly bordered, strongly contracted towards apex, slightly sinuate before hind angles, with 1 pair of latero–; marginal setae at about the widest point, the posterior pair absent, hind angles subrectangular, front angles almost rounded; basal margin almost straight, apical margin slightly convex; base slightly narrower than apex, PBW/PAW=0.88; median line clear, front transverse impression obscure, basal transverse impressions well − defined; basal foveae small. Scutellum large. Elytra: Elongate ovate, distinctly more slender than in L. nishikawai , wider than pronotum, more contracted towards base than towards apices, strongly convex, distinctly longer than wide, EL/EW=1.65, widest at about middle; basal part comparatively narrow, concave on declivity; shoulders evident, prehumeral borders complete, distinctly oblique, entire lateral margins ciliated throughout, more distinctly so on prehumeral parts (which are not serrate); striae evenly and moderately punctate, with punctures much smaller than those in L. nishikawai , 1 st stria joined with 2 nd apically, 3 rd extended to subapex forming anastomosis with 4 th; 5 th, and 8 th striae extended to subapex, 6 th and 7 th ended before subapex; apical (recurrent) stria rather long, moderately punctate, and directed to 5 th stria; intervals rather flat, 1 st − 7 th intervals glabrous, outer ones covered with very short and irregularly sited bristles; 3 rd stria with only a dorsal setiferous pore located slightly before middle of elytra; preapical pore absent, both apical pores located on apical stria at each terminus respectively; chaetatoxal pattern of marginal umbilicate pores similar to that of L. nishikawai ; scutellar stria absent. Venter: Head and prosternum smooth and glabrous, meso– and metasterna covered with hair-like and irregularly dispersed setae; abdominal ventrites pubescent, ventrites III − VI covered with rather long, hair-like setae especially on median portions, and with pair of paramedial setae; ventrite VII pubescent with fine and very short bristles, with only 1 pair of anal setae in male. Male genitalia ( Fig. 3 ): Moderately sclerotized and small, about 1/7 as long as body, strongly arcuate before middle, less so in apical half, distinctly contracted and narrowed towards apex which is slightly reflexed; basal part very large and thick, slightly curved ventrally, basal orifice rather wide; in dorsal view, the apical lamella broad and enlarged, rounded at apex; sagittal aileron small; parameres fairly large, the right as long as the left, each provided with 3 and 4 long setae at apex, respectively.

Female. Unknown.

Etymology. The name refers to the type locality.

Remarks. Libotrechus duanensis is the second known species of Libotrechus , differing from L. nishikawai in the many character states noted above (see the key for details). The male genitalia are quite similar to those of L. nishikawai males, but the basal orifice is stouter in L. duanensis , and both parameres have fewer long setae at the apices (each with 5 and 6 apical setae in L. nishikawai males).

Distribution. Guangxi (Du’ an), China. Known only from a limestone cave called Shuiyuan Dong, at Shangmo Tun, Longfu Xiang ( Fig. 1 ). The cave is composed of two layers. The lower layer is an underground river which provides a water source for the villagers and is inaccessible. The upper layer is a short passage, 1.0– 1.5 m high, 2.0–4.0 m wide, and about 15 m long. The entrance of the cave and environment nearby are shown in Figs. 4 − 7.

Figures

Fig. 1. Distribution of Libotrechus species. ★ = L. nishikawai, • = L. duanensis; a) Map of China indicating location of enlarged area.

Fig. 2. Habitus of Libotrechus duanensis, male, holotype.

Fig. 3. Male genitalia of Libotrechus duanensis, holotype. a) Median lobe and parameres, lateral view, b) Apical part of median lobe, dorsal view.

Figs. 4−7. Shuiyuan Dong. 4−5) Entrance; 6−7) Surrounding areas.