Youtrechus zijunae Tian & Huang & Jia 2023, n. sp.

Youtrechus zijunae n. sp. Figures 1n, 2–4 Material. Holotype male, 29.73 °N / 114.24 °E, 160 m, a limestone cave called Feixian Dong, Xian’an District, Xianning, Hubei, 2019. VII. 13, Mingyi Tian, Mengzhen Chen, Zijun Ma & Jingli Cheng leg., in SCAU; paratypes: 10 males and 3 females, idem, in SCAU. Diagnosis. Semi-aphenopsian and medium to large sized for cave trechines, with moderately elongated body and appendages, eyeless and depigmented; fore part (head plus prothorax) evidently shorter than elytra, surface smooth. Description. Length: 6.5–6.9 mm; width: 1.9–2.1mm. Habitus as in Figure 2. Body yellowish brown, but antennae, mouthparts palps and tarsi pale; moderately shiny and whole body glabrous though genae with a few setae; microsculptural engraved meshes isodiametric on head, transverse striate on pronotum and elytra; fore body much shorter than elytra, (HLm+PL) / EL = 0. 80–0.82. Head stout, slightly longer than wide, HLm/HW = 1.58–1.64, HLl/HW = 1.16–1.22; genae fairly developed, slightly expanded, widest at about 1/3 of head from neck to apical margin of labrum; frons rather flat, vertex convex, frontal furrows widely and strongly divergent posteriad; clypeus transverse, quadrisetose; labrum transverse, frontal margin slightly emarginate, 6-setose; two pairs of supraorbital setiferous pores present at about middle and 1/4 of head from labrum; labial suture clearly visible, mentum bisetose on either side of tooth, mental tooth short and blunt at tip, basal fovea widely concave; submentum 6-setose; ligula thick and short, bisetose at apex; palps moderately elongated, 2 nd labial palpomere 1.3 times as long as 3 rd, the former bisetose on inner margin, with a seta medially on outer margin and another on out subapex, the latter glabrous; 3 rd maxillary palpomere 1.1 times as long as 4 th, both glabrous; suborbital pore just between base and submentum (Figure 3A). Antennae thin and rather long, but not extended beyond elytral apices, longer in male; the 1 st antennomere stouter, as long as the 2 nd, the 3 rd – 5 th longest, the 11 th slightly longer than 10 th, the comparative length of each antennomere from the 1 st to 11 th in holotype as: 1 st (1.00) / 2 nd (1.17) / 3 rd (1.83) / 4 th (1.78) / 5 th (1.89) / 6 th (1.67) / 7 th (1.61) / 8 th (1.44) / 9 th (1.39) / 10 th (1.28) /11 th (1.56). Pronotum quadrate, slightly longer than wide, PL/PW =1.07–1.11; wider than head, PW/HW = 1.21–1.23, slightly longer than head excluding mandibles, PL/HLl = 1.03–1.05; widest a little before middle, gently narrowed anteriorly and posteriorly, latero-margins finely bordered; front slightly concave, the base is prominent, with the presence of secondary angles, strongly sinuate on sides, making a sharp, though rectangular, hind angle on each side; anterior latero-marginal setae at about apical 1/8, posterior ones just on hind angles; disc moderately convex; median line well-defined, basal transversal impression and foveae well-marked. Scutellum fairly small. Elytra elongated ovate, much longer than wide,EL/EW=1.64–1.66; much wider than pronotum,EW/PnW=1.75– 1.76; widest at about 3/7 of elytra from base, lateral sides smooth, finely bordered throughout, marginal gutters wellmarked; slightly depressed medially near base, disc moderately convex; punctures of striae invisible, intervals more or less subequal in width except 1 st one. Chaetotaxy (Figure 3B): anterior and medial dorsal pores located on 3 rd stria, at about 2/13 and 4/13 of elytra from base respectively; posterior dorsal pore located on 5 th interval at about 6/13 of elytra from base; the preapical pore located at the apical anastomosis of 2 nd and 3 rd striae, and at about apical 2/13 of elytra, much closer to elytral suture than to apical margin; basal pore present; 1 st and 2 nd marginal umbilicate close to marginal gutter; 4 th pore distant from 3 rd; 5 th and 6 th pores located at about middle of elytra, close to each other; 7 th, 8 th and apical pores distant from marginal gutter; the anguloapical one present, subequal to elytral margin and suture. Legs thin and slender, bearing short pubescence; the 1 st and 2 nd protarsomeres widened in male, distinctly denticulate inwardly; the 1 st protarsomere distinctly widened in female; the 1 st tarsomere much shorter than 2 nd –4 th tarsomeres together in fore leg, whereas as long as those in middle and hind legs respectively. Ventrites smooth, IV–VI each with two pairs of paramedial setae, together with several pubescence in middle portion, VII bisetose apically in male, 6-setose in female. Male genitalia (Figure 3C, D): The median lobe of aedeagus quite large, distinctly arcuate near base; base large, about 1/3 as long as the median lobe; the apical half nearly straight, slightly narrowed towards apex, which is blunt and slightly bent at tip; endophallus armed with a large and long copulatory piece which is about 3/8 as long as the median lobe; in dorsal view the apical lobe much wider than long, broadly rounded at apex; parameres less developed, much shorter than the median lobe, each bearing three long setae at apex. Etymology. Dedicated to Ms. Zijun Ma, a member of SCAU caving team, who is one of the collectors of the type series. Distribution. China (Hubei: Xianning). Known only from the cave Feixian Dong (Figure 4). Located in Huaping Shan, Tingsi, southern Xianning City, Feixian Dong is 1.5 km long. This obsolete show cave retains natural conditions in some parts along the main passage which are suitable for cave animals (Figure 4A–C). The beetles were collected from several sites inside the cave, on the ground or under stones, from 160 to 800 m from the entrance (Figure 4F). Other animals observed in Feixian Dong were bats, millipedes of Eutrichodesmus sp. and Skleroprotopus sp. (Figure 4D, E, G).Published as part of Tian, Mingyi, Huang, Sunbin & Jia, Xinyang, 2023, A contribution to cavernicolous beetle diversity of South China Karst: eight new genera and fourteen new species (Coleoptera: Carabidae: Trechini), pp. 1-66 in Zootaxa 5243 (1) on pages 6-10, DOI: 10.11646/zootaxa.5243.1.1, http://zenodo.org/record/764240