Boreaphaenops liyuani, Tian & He, 2020

Tian, Mingyi & He, Li, 2020, A contribution to the knowledge of cavernicolous ground beetles from Sichuan Province, southwestern China (Coleoptera, Carabidae, Trechini, Platynini), ZooKeys 1008, pp. 61-91 : 61

Boreaphaenops liyuani sp. nov. Chinese name: 李圆北盲步甲 Figs 2 , 4E , 9 , 10

Material.

Holotype: female, the cave Hanwang Dong, Zhongbai, Zengjia, Chaotian, Guangyuan, Sichuan (四川省广元市朝天区曾家镇中柏村汉王洞), 32.577297°N, 106.106979°E, 1210 m, 2020-VI-6, leg. Li He, Yuan Li & Yimei Wen, in SCAU.

Diagnosis.

An aphaenopsian, small-sized beetle, eyeless and depigmented, body distinctly elongate, with thin and long appendages, densely pubescent on head and elytra, presence of only a dorsal setiferous pore along the 3rd stria on each elytron.

Description.

Length: 5.2 mm, width: 1.3 mm. Habitus as in Fig. 9 .

Body brown, but antennae, palps and tarsi paler; head and elytra covered with dense pubescence, pronotum glabrous. Underside of head with a few sparse setae, of thorax and abdominal ventrites glabrous. Microsculpture engraved meshes more or less isodiametric on head, strongly transverse on pronotum and densely striate on elytra.

Head similar to B. angustus Uéno, 2002 from the cave Lenre Dong in Shenlongjia, western Hubei Province ( Uéno 2002), but with only two pairs of supraorbital setiferous pores instead of three; elongate, much longer than wide, HLm/HW = 2.56, HLl/HW = 1.58; nearly parallel-sided due to genae not convex instead of slightly expanded; widest at about middle of head excluding mandibles, neck constriction well-marked; frons moderately, and vertex strongly convex respectively; anterior and posterior supraorbital pores located at middle and basal 2/9 of head excluding mandibles, frontal furrows strongly divergent, ended near posterior supraorbital pores; clypeus 6-setose; labrum transverse, straight at frontal margin, 6-setose; mandible thin and elongate, gently hooked apically, right mandibular tooth bidentate though distinctly reduced; labial suture completely disappeared; mentum tooth very small, shorter than half of the lateral lobes, bifid at tip, with two setae on each side of base; ligula adnated with paraglossae, 8-setose at apex; basal foveae large and separated; submentum 10-setose; palps thin, slender and glabrous, but bisetose on inner margin of the 2nd labial palpomere which is very long and 1.70 times as long as 3rd; 3rd maxillary palpomere 1.15 times as long as 4th; suborbital pores intermediate between neck and submentum; antennae pubescent from the 2nd antennomere, 1st antennomere stouter covered with several long setae, slightly longer than 2nd; 3rd to 6th longer, subequal to one another; relative length of each antennomere compared with the 2nd in the holotype as: the 1st (1.05), 2nd (1.00), 3rd (1.82), 4th (1.82), 5th (1.82), 6th (1.82), 7th (1.82), 8th (1.64), 9th (1.64), 10th (1.46) and 11th (1.27).

Prothorax slightly tumid at sides, propleura medially visible from above, slightly wider than pronotum; pronotum similar in B. angustus but more elongate, fore angles distinct, hind ones nearly rectangular; much longer than wide, PnL/PnW = 1.32; slightly shorter than head without mandibles, PnL/HLl = 0.95; wider than head, PnW/HW = 1.19; widest at about 3/4 from base; lateral margins almost vanished at 1/4 portion from base, finely bordered in other parts; base and front nearly straight, unbordered, the former narrower than the latter, Pnb/Pnf = 0.69; anterior latero-marginal setae at about 1/6 from front, posterior ones before hind angles; disc moderately convex, mid-line clear, both front and posterior transversal impressions faintly marked. Scutellum small and elongated.

Elytra longer than fore body including mandibles, much longer than wide, EL/EW = 1.94; nearly twice as wide as prothorax, EW/PrW = 1.96; base unbordered; similar in B. angustus but devoid of humeral angles, lateral margins finely but well-bordered throughout, smooth; widest at about middle, gently contracted towards base but strongly to apices; disc moderately convex though depressed near base just behind basal pores; striae faint but well-indicated from the 1st to 4th; basal pore present at sides of scutellum, only a median dorsal pore present along the 3rd stria at a little behind middle; preapical pore present at about apical 1/7 of elytra, much closer to suture than to apical margin; marginal umbilicate pores well-marked, 2nd closer to marginal gutter than others, prehumeral set (1st to 4th) equidistantly located (Fig. 4E ).

Legs densely pubescent; 1st tarsomere much and slightly shorter than 2nd-4th combined in fore and middle legs, whereas as long in hind ones; tibiae without longitudinal sulci. Abdominal ventrite IV-VI each with two pairs of paramedial setae, ventrite VII quadrisetose.

Male. Unknown.

Etymology.

In honour of Mr. Yuan Li (Deyang, Sichuan), a co-collector of the type material.

Remarks.

The cave Hanwang Dong is about 400 km in a straight line from Lengre Dong, the locality of B. angustus Uéno, 2002, though both localities belong to same range of the Daba-Micang Mountains. Although B. liyuani sp. nov. has several differences from B. angustus which are probably of generic importance, e.g. completely fused mentum and submentum (labial suture visible in the latter species), thin and straight mandibles with tooth distinctly reduced (well-developed in B. angustus ), smooth elytral lateral margins (ciliate in B. angustus ), and very long 2nd labial palpomere which is 1.7 time as long as the 3rd (such a feature never observed in other Chinese cave trechines), we prefer to describe it as a member of Boreaphaenops at present as only a single female exemplar is available. In addition, it also differs from B. angustus in having smaller body size, presence of only a pair of posterior supraorbital pores on the head instead of two, pronotum well-angulate on hind and fore angles instead of rounded, lack of prehumeral angles of elytra which have only a single dorsal setiferous pore along the 3rd stria instead of three in B. angustus , and with equidistant prehumeral pores of the marginal umbilicate series, vs. 4th pore far from 3rd in B. angustus .

Distribution.

China (Sichuan). Known only from the cave Hanwang Dong in Guangyuan (Fig. 2 ).

Boreaphaenops liyuani sp. nov. is the first representative of the genus from Sichuan Province, living together with Chu pheggomisetoides gen. nov. & sp. nov., Agonotrechus sinotroglophilus Deuve, 1999 and Pterostichus (Huaius) hanwang Tian & He, 2020. It is very rare in the cave: three surveys carried out by SCET led to the discovery of only a single female, which was collected under a stone at the water edge in the innermost main passage in the cave (Fig. 10 ).

Figures

Figure 2. Map of Sichuan Province showing the locations of the related caves.

Figure 4. Cave trechine beetles A ventral head of Uenoaphaenops fani (Ueno, 2003), comb. nov., female B ventral head of Chu pheggomisetoides gen. nov. & sp. nov., female C-E elytral chaetotaxy of Uenoaphaenops fani (Ueno, 2003), comb. nov., female, Chu pheggomisetoides gen. nov. & sp. nov., female paratype, and Boreaphaenops liyuani sp. nov., female holotype. Scale bars: 1.0 mm.

Figure 9. Habitus of Boreaphaenops liyuani sp. nov., female holotype.

Figure 10. An individual of Boreaphaenops liyuani sp. nov. running in cave.