Sinaphaenops (Sinaphaenops) chengguangyuani, Ma & Huang & Tian, 2020

Ma, Zijun, Huang, Sunbin & Tian, Mingyi, 2020, Two new species of cavernicolous trechines from central Guizhou and northwestern Guangxi, China (Coleoptera: Carabidae: Trechinae), Zootaxa 4861 (4), pp. 581-593 : 582-587

Sinaphaenops (Sinaphaenops) chengguangyuani n. sp.

( Figs. 1–6 )

Material. Holotype: male, cave Shuijing Dong , Baihuashu , Shibantan Cun , Xima Zhen, Longli Xian, Qiannan Miao & Buyi Zizhizhou, Guizhou Province, China, 26°36'45.57"N, 107°01'17.80"E, 1546 m in altitude, 30-I-2020, leg. Guangyuan Cheng & Jingyi Lai, deposited in SCAU . Paratypes: 2 males, Guangyuan Cheng, 26-VI-2020, deposited in SCAU ; 2 males & 2 females, same locality, 26-VI-2020, leg. Mingyi Tian, Yi Zhao, Guangyuan Cheng, Xiaohong Jin & Chenggang Wang, deposited in SCAU .

Description. Length: 6.5–7.1 mm from apex of right mandible to elytral apex, 6.1–6.4 mm from labrum to apex of elytra; width: 1.60–1.79 mm. Habitus as in Fig. 1 . Fore body (including mandibles) longer than elytra, (HLm+PrL)/EL=1.02–1.03. Overall yellowish brown, with paler tarsi and palps; body moderately shiny, impunctate and glabrous; microsculpture meshes transversely striate on vertex of head and pronotum, moderately transverse on clypeus and frons of head and elytra.

Head elongate subtriangular, much longer than wide (HLm/HW=2.84–2.90, HLl/HW=2.24–2.26), widest at about 3/7 from base (including mandibles); neck constriction wide, about 0.48–0.49 times as wide as head; frons depressed, frontal furrows well-marked, not parallel-sided, strongly divergent posteriorly; clypeus transverse, 4-setose; labrum transverse, 6-setose; mandibles stout and long, with obvious bidentate; two pairs of frontal setiferous pores present, the posterior more narrowly spaced than the anterior, at about the 1/3 level between neck constriction and anterior frontal pores; labial suture clearly visible, submentum 10-setose; mentum with two setae near base of median tooth which is thin and bifid; basal foveae concave and separated each other; ligula adnate to paraglossae, 10-setose; palps long, slender and glabrous except for the 2 nd labial palpomere which possesses two setae on inner margin and another seta on outer margin; the 2 nd labial palpomere 1.2 times longer than the 3 rd; the 3 rd maxillary palpomere 1.3 times longer than the 4 th. Ventral head with sparse and long setae; suborbital setae present, closer to neck of head than to submentum. Antennae slender, both the 10 th and 11 th antennomeres extending beyond elytral apices; the 1 st antennomere stouter and shorter than others, the 4 th longest, the comparative length ratio of antennomere as follows: 1 st (1.00), 2 nd (1.33), 3 rd (1.40), 4 th (2.07), 5 th (1.87), 6 th (1.80), 7 th (1.50), 8 th (1.37), 9 th (1.33), 10 th (1.10) and 11 th (1.20).

Prothorax stouter than in S. banshanicus Tian et al., 2017 and S. lipoi Chen, Huang & Tian, 2020 ( Fig. 2 ), much shorter than head (PrL/HLm=0.47–0.61, PrL/HLl=0.75–0.80); distinctly wider than head (PrW/HW=1.24–1.33); widest at about 2/5 from base; anterior lateral-marginal setae present at about 1/3 distance from front; propleura distinctly expanded and visible from above (PrW/PnW=1.11–1.14); pronotum faintly wider than head (PnW/ HW=1.09–1.20), widest at about 1/2 from base; base distinctly wider than front (PbW/PfW=1.24–1.27); front not stoutly emarginate; lateral margins feebly sinuate, posterior angles acuminate, front angles obtuse and rounded; median line obvious.

Elytra oval-like, much longer than pronotum (EL/PnL=2.55–2.68), moderately elongate for Sinaphaenops species, about twice as long as wide (EL/EW=1.94–2.02), widest at about 3/5 from base, basally narrow and depressed, middle strongly convex; shoulders distinctly oblique, not serrulate, humeral angles broad; lateral margins finely margined and visible throughout, not parallel-sided; elytral striae generally invisible except punctures of the 1 st stria more or less clear at basal part. Chaetotaxy similar in S. (s. str.) banshanicus and S. (s. str.) lipoi ( Fig. 3 ): presence of two dorsal pores on approximate position of 3 rd stria, at about 3/10 and 1/2 from elytral base, respectively; presence of preapical pore, which is well-marked, closer to suture than to apical margin of elytra; 1 st umbilicate pore of the humeral group roughly shifted to the position of 5 th interval and away from marginal gutter; 2 nd and 3 rd pores close to each other, the former near the marginal gutter; 4 th pore more or less located on the site of 5 th stria, closer to 5 th pore than to 3 rd; 5 th and 6 th pores of the middle group close to each other, both also widely distant from marginal gutter ( Fig. 3A ).

Legs slender, the 1 st tarsomere shorter than 2 nd– 4 th tarsomeres together in fore legs, while slightly longer in middle and as long as in hind legs, respectively. The 1 st and 2 nd protarsomeres modified in male, each denticulate on inner side of apex, with spongy setae ventrally.

Prosternum with several setae near base and apex, propleura smooth and glabrous; fore, middle and hind coxae with several setae. All ventrites sparsely setose; ventrite IV–VI each with 4 paramedial setae, and a few additional setae which are much shorter, ventrite VII with two pairs of setae in male, but three pairs in female.

Male genitalia ( Fig. 4 ) moderately sclerotized, distinctly arcuate at middle in lateral view, widely membranous on its dorsal part; base large, sagittal aileron large and almost rounded; apex almost straight, and blunt at tip; inner sac armed with a wide copulatory piece, which is about 1/5 as long as median lobe; apical lobe wide, although longer than wide, slightly sinuate on the right side, broadly rounded at apex ( Fig. 4B ); parameres elongate and welldeveloped, each armed with two long setae at apex ( Fig. 4A ); genital ring triangular ( Fig. 4C ).

Remarks. This new species belongs to the same lineage as Sinaphaenops (s. str.) banshanicus and S. (s. str.) lipoi , in possessing anterior lateral-marginal setae on pronotum and preapical dorsal pores on elytra. It differs from the above two species by the shorter pronotum and presence of a distinct sagittal aileron on the male genitalia.

Etymology. Dedicated to Mr. Guangyuan Cheng, who discovered this interesting species.

Distribution. Guizhou (Guiyang). Known only from a limestone cave called Shuijing Dong ( Fig. 5 ). The single beetle was collected on wet floor inside the cave, a place about 250 meters from the entrance ( Fig. 6 ).

Figures

FIGURE 1. Habitus of Sinaphaenops (s. str.) chengguangyuani n. sp..

FIGURE 2. Pronotum of Sinaphaenops species (A. S. (s. str.) chengguangyuani n. sp., holotype, male; B. S. (s. str.) lipoi, holotype, male; C. S. (s. str.) banshanicus, holotype, male).

FIGURE 3. Elytra chaetotaxy of Sinaphaenops species (A. S. (s. str.) chengguangyuani n. sp., holotype, male; B. S. (s. str.) lipoi, holotype, male; C. S. (s. str.) banshanicus, holotype, male).

FIGURE 4. Male genitalia of Sinaphaenops (s. str.) chengguangyuani n. sp., holotype (A. median lobe and parameres, lateral view; B. apex of median lobe, dorsal view; C. genital ring, ventral view).

FIGURE 5. Distribution map of the subgenus Sinaphaenops.

FIGURE 6. Cave Shuijing Dong, type locality of Sinaphaenops (s. str.) chengguangyuani n. sp. (A. entrance; B, C. cave environment; D. Sinaphaenops (s. str.) chengguangyuani n. sp.).