Oodinotrechus yinae sp. n. (Cave Chaotianyan, Pingle County)

Similar to the nominate subgenus Oodinotrechus (s. str.) Uéno, 1998, but smaller and slenderer; body, in particular head and elytra, longer; head narrower, genae only slightly expanded laterally; pronotal base with sides much in advance of nearly straight medial part, without a gap submedially on each side between pronotum and elytra; scutellum visible from above; elytra slenderer, with two dorsal pores on 3^rd and 4^th striae, respectively; umbilical setae 5 and 6 widely separate, distance between them almost triple as that between setae 4 and 5; an additional striole running inside and forming a crescent with apical stria; aedeagus short and stout, without sagittal aileron.

Pingleotrechus subgen. n. is similar to Oodinotrechus (s. str.) Uéno, 1998, occurring in Maolan-Mulun karst, in many aspects, viz. short and stout body, short legs and antennae, entire frontal furrows, tridentate right mandible, well-defined labial suture, two pairs of supraorbital setigerous pores present on head, campanulate pronotum, ciliate elytral margin, presence of two dorsal pores on elytron, and unmodified protarsi in male. However, Pingleotrechus is different from the nominate subgenus in many characters as follows: body smaller and slenderer; head slightly expanded laterally (versus strongly expanded); second dorsal pore situated on 4^th elytral stria (versus on 5^th stria); umbilicate setigerous pores of the middle group (pores 5 and 6) widely separated (versus very close to each other); an additional, inner, apical striole, present (versus absent); male genitalia stouter, without sagittal aileron (versus with a large sagittal aileron).

Refers to Pingle County, the locality of the type species.

China (northeastern Guangxi) (Fig. 1).

A small, short and stout beetle, anophthalmic and depigmented, with short appendages, fore body distinctly shorter than elytra, head short and narrow, with two pairs of supraorbital setae, mentum and submentum separated by clear labial suture, pronotum broad and campanulate, both lateromarginal setae present, elytra serrate and ciliate, shoulders distinct, 5^th and 6^th pores of the marginal umblicate series widely separated, a crescent-form structure present on apical part of each elytron.

Length: 4.0–4.8 mm; width: 1.3–1.7 mm. Habitus as in Fig. 2.

Figure 2. 

Oodinotrechus (Pingleotrechus) yinae subgen. n., sp. n. Habitus, holotype, male (chaetotaxy indicated by small white round points on left part of the body) (photos Xinhui Wang).

Depigmented; yellowish to reddish dark brown, very shiny, palps and tarsi light yellow.

Genae with several sparse and short setae, frons and vertex glabrous; a pair of suborbital setae present between mentum and prosternum; disc of pronotum with four erect setae each side of median line; propleura and mesosternum glabrous, pro- and metasterna with a few setae medially; elytra, prosternum and abdominal ventrites sparsely pubescent, entire legs pubescent. Microsculpture formed by faintly engraved transverse meshes on head and elytra, moderately transverse on pronotum.

Head anophthalmic, subquadrate, distinctly longer than wide, HLm/HW=1.74–1.79, HLl/HW=1.22–1.29; frons depressed and almost flat, vertex slightly convex, frontal furrows long and deep. Genae slightly expanded laterally, distance between anterior and posterior supraorbital pores almost as great as minimum distance between frontal furrows. Mentum bisetose, with medial tooth simple and blunt. Submentum with a row of 6 setae. Palps slender, 3^rd maxillary palpomere as long as 4^th while 2^nd labial palpomere longer than 3^rd. Antennae short and subfiliform, extended to about basal 1/3 of elytra and pubescent from 2^nd antennomere; 1^st antennomere with several additional setae near apex, slightly longer than 2^nd, 3^rd longest; antennomeres 4–10 decreasing gradually in length, 11^th as long as 4^th.

Pronotum transversely campanulate, PW/PL=1.40–1.47, as long as head, widest just before hind angles, which are widely obtuse and not denticulate; sides gently and gradually converging apicad in a smooth arc; fore angles are rounded off; anterior margin nearly straight. Base nearly straight, markedly wider than apex, PWb/PWf=1.67–1.71, with sides in advance of median part and oblique towards hind angles; lateral margins widely expanded and reflexed; anterolateral seta a third from apex, posterolateral seta just in front of hind angle. Disc moderately convex. Median line fine and deep. Both frontal and basal transverse impressions well-marked, basal foveae indistinct.

Scutellum large, visible from above. Elytra longer than forebody, EL/(HLm+PL)=1.32–1.39, longer than wide, EL/EW=1.54–1.79, with unbordered base, rounded shoulders and narrowed apex; widest about 1/3 from base; lateral margin serrate and ciliate throughout. Disc moderately convex, distinctly depressed at base and along suture. Parascutellar striole absent. 1^st stria distinct, 2^nd and 3^rd faint but traceable; apical striole long and well-marked. Intervals flat, 2^nd wider than any other. Basal setigerous pore present, anterior dorsal pore on 3^rd stria about 1/6 from base, second pore on 4^th stria a little behind middle; preapical pore distinct, inserted at anterior end of apical striole about 1/4 from apex, where 3^rd and 4^th striae anastomosed. Umbilicate setigerous pores subdivided into subhumeral group (setae 1–4, closely spaced), middle group (setae 5 and 6, widely separated) and preapical group; seta 5 much closer to 4^th than to 6^th, 6^th closer to 7^th than to 5^th; distance between 5^th and 6^th about three times greater than between 5^th and 4^th, preapical pore equidistant from suture and from apex of elytra. Apical stria (Fig. 3a) and an additional, inner, striole (Fig. 3b) rising from preapical pore and forming a crescent combined; this additional striole gently curved inwards behind and not quite reaching stria 1.

Figures 3–4. 

Oodinotrechus species, apical part of elytra 3O. (Pingleotrechus) yinae subgen. n., sp. n. 4O. (O.) liyoubangia apical stria b additional striola.

Protibia straight, without longitudinal external sulcus. Protarsomeres 2–4 nearly moniliform. 1^st tarsomere slightly shorter than or as long as, or longer than 2–4^th combined in protarsi, mesotarsi, and metatarsi, respectively.

Male genitalia (Figs 5–6): Aedeagus moderately sclerotized; median lobe small, short and stout, moderately arcuated in lateral view; ventral margin deeply concave in median portion, then gently and almost straight towards apex, which is rather broad, not tube-like. Basal portion very large, with a large basal orifice, sagittal aileron absent. Dorsal orifice wide and long. Inner sac armed with an indistinct copulatory piece, about 1/3 as long as aedeagus. Apical lamella in dorsal view rather long and thin, not parallel-sided, gently narrowed towards apex which is rounded at tip. Parameres short and narrow, right slightly longer than left, both are broadly rounded at apex and bearing three and four long setae, respectively.

Figures 5–6. 

Oodinotrechus (Pingleotrechus) yinae subgen. n., sp. n., aedeagus 5 median lobe and parameres, lateral view 6 apical lobe of median lobe, dorsal view (photos Xinhui Wang).

This new species is named in honor of Ms. Haomin Yin, an active member in our cave biological study team.

Northeastern Guangxi (Fig. 1). Known only from cave Chaotianyan, the type locality. The cave Chaotianyan is located in Letang village (Fig. 7), Ertang, Pingle County, at the southern part of Guilin karst. It opens in a subway of a hill, at about 60 m above foot, with a big entrance (Fig. 8). There is a large hall after the entrance, decorated by different deposits (Figs 9–11). It is a long cave according to the villagers, but detailed information is still not available. The beetles were collected in a dark and wet area under stone, not far from the entrance.

Figures 7–11. 

The type locality of the cave Chaotianyan and its surroundings 7 Fongchong landscape in Letang area 8 cave opening 9–11 a hall and deposits inside the cave (photos Mingyi Tian).

It is an interesting discovery to find an Oodinotrechus species in Guilin karst, northeastern Guangxi, because cave Chaotianyan, the type locality of O. yinae sp. n. is approximately 300 km away from the Maolan-Mulun karsts in the bordering areas between southernmost Guizhou and northernmost Guangxi where other two species of Oodinotrechus are found. However, in the Letang area there is a Fengchong landscape (Fig. 7), rather than Fenglin landscape which is dominant in other parts of the Guilin karst (Zhu 1988).

Holotype: male, Guangxi: Guilin: Pingle: Ertang: Letang: cave Chaotianyan, 110°45’501"E / 24°37’075"N, 5-XII-2011, Mingyi Tian, Weixin Liu & Haomin Yin leg, in SCAU. Paratypes: 3 males and 4 females, same data as holotype; 6 males and 4 females, same cave, 29-IV-2013, Mingyi Tian, Weixin Liu, Haomin Yin & Feifei Sun leg. All are deposited in SCAU, except one male paratype in each of IOZ, MNHN and ZUBM, respectively.