Chu, 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

Chu gen. nov. Chinese name: 初盲步甲属 Figs 2 , 4B, D , 5C, D , 7 , 8

Type species.

Chu pheggomisetoides sp. nov., from the limestone cave Hanwang Dong in Guangyuan, northeastern Sichuan.

Generic characteristics.

Medium-sized, somewhat similar to the Balkan genus Pheggomisetes Knirsch, 1923 in appearance especially head and pronotum (Fig. 7 ); anophthalmic and depigmented; body moderately elongate, with rather thin and slender appendages. Head strongly expanded laterally and convex though shorter than long, two pairs of supraorbital setiferous pores present; frontal furrows long and well-marked; labrum widely emarginated at front, mandibles widened and developed, apices strongly hooked, right mandibular tooth tridentate; labial suture visible at side, completely disappeared medially (Fig. 4B ); mentum bisetose, base largely concave, submentum 8-setose; antennae thin and very long, extending over apices of elytra. Propleura invisible from above; pronotum subcordate, transverse, hind angles very sharp and distinctly protruded backwardly which is similar in Pheggomisetes , only presence of the anterior pair of latero-marginal setae. Elytra elongated ovate, twice as long as wide, much longer than fore body; prehumeral angles rounded off; lateral margins well-bordered throughout, finely ciliate on shoulders, whereas smooth on other parts; disc moderately convex, striae noticeable though distinctly reduced; two pairs of dorsal and the preapical setiferous pores present; the humeral group of the marginal umbilicate pores not aggregated, the 1st pore inwardly shifted to the site of 7th stria, only the 2nd pore closest to marginal gutter, 4th shifted posteriad; 5th and 6th pores closely spaced (Fig. 4D ). The 1st and 2nd protarsomeres modified in male, distinctly widened and bluntly denticulate inward at apices, and with spongy setae ventrally. Ventrite VII with one pair of apical setae in male, whereas two pairs in female. Male genitalia with median lobe almost straight, suddenly widened at apical part; in lateral view, apex notched dorsally (Fig. 5C, D ).

Remarks.

Although Chu gen. nov. resembles the Balkan cavernicolous genus Pheggomisetes Knirsch, 1923 ( Knirsch 1923; Vrbica et al. 2017) in the shape of head and pronotum, this must be a case of convergence because the faunas in the Balkan Peninsula and China are completely different. Indeed, there are many cases of large gaps in cave trechines between Europe and China, e.g., Doderotrechus from Western Italy vs. Trechus of the dacaitranus group ( Trechus bastropi ) from Tibet ( Faille et al. 2013). Apart from the similarities of the head and pronotum, both Chu and Pheggomisetes are very different in many aspects including outlines of head, prothorax and elytra, and in particular the chaetotaxic pattern on head and elytra.

As the fauna of subterranean ground beetles are still not well known, the phylogenetic position of Chu gen. nov. among Trechini is unknown at present, like many other genera. Its peculiar characters, such as ellipsoidal head with deep emarginated labrum, stout mandible, subcordate pronotum with sharp and backwardly protruded hind angles, and almost straight median lobe which is enlarged and notched at the apex isolate Chu gen. nov. from all other Chinese trechines. Beside comparative morphological study, evidence from molecular analysis would be valuable in determining its position.

Etymology.

" Chu " means "the first time" in Chinese, suggesting that this species was the first subterranean beetle discovered by Li He (the second author). Gender masculine.

Generic range.

China (Sichuan) (Fig. 2 ). Monospecific genus, known only from the cave Hanwang Dong in Chaotian, Guangyuan.

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 5. Male genitalia of cave trechine species, lateral and dorsal views A, B Uenoaphaenops fani (Ueno, 2003), comb. nov. C, D Chu pheggomisetoides gen. nov. & sp. nov.

Figure 7. Habitus of Chu pheggomisetoides gen. nov. & sp. nov., male holotype.

Figure 8. Cave Hanwang Dong, the type locality of Chu pheggomisetoides gen. nov. & sp. nov. and Boreaphaenops liyuani sp. nov., and some sympatric cave animals A, B habitat inside the cave, arrow in A indicates the place where a Chu pheggomisetoides gen. nov. & sp. nov. was found, arrow in B indicates the place where the single female of Boreaphaenops liyuani sp. nov. was found C an individual of Chu pheggomisetoides gen. nov. & sp. nov. running in cave D a ground beetle's larva was trapped in web of spider Pseudonesticus sp. E a Nepalella millipede F a bat G a cricket H Gammarus qinling Hou & Li, 2018 I a dipluran.