A review of the cavernicolous genus Guiaphaenops Deuve, with the description of a new species (Coleoptera, Carabidae, Trechinae)

Abstract The subterranean ground beetle genus Guiaphaenops Deuve, 2002 is taxonomically reviewed. This poorly known genus is different from Guizhaphaenops Vigna Taglianti, 1997 in having convex propleura which is visible from above and elytral chaetotaxy especially the humeral group of the marginal umbilicate series, in which the 1st pore is transversely and backwardly shifted. The second species, G. deuvei Tian, Feng & Wei, sp. n., is described from a limestone cave at Yangli Cun (Village), Lingyun Xian (County), Baise Shi (Prefecture), northwestern Guangxi Zhuang Autonomous Region, China. A key to the species and a distribution map of Guiaphaenops are also provided.

In recent years, more material of Guiaphaenops has been collected by SCAU team during the cave biological surveys carried out in Lingyun. The findings make it possible to contribute to the knowledge of this interesting genus by providing the new record for G. lingyunensis and the description of a new species.

Material and methods
The blind beetles for this study were collected visually using an aspirator and preserved in 50% ethanol before study. All specimens are deposited in the insect collection of South China Agricultural University, Guangzhou, China (SCAU).
Techniques, terminology and abbreviations used in the text follow Tian et al. (2016).

Genus Guiaphaenops Deuve, 2002
Subgenus Guiaphaenops (of Guizhaphaenops Vigna Taglianti, 1997), Deuve, 2002: 516 (type species: Guizhaphaenops lingyunensis Deuve, 2002. Genus Guiaphaenops, Uéno, 2006: 22 Main generic characteristics. Median sized and semi-aphaenopsian beetles, eyeless and depigmented; appendages rather long, antennae extending at (female) or over (male) elytral apices; dorsal surface glabrous though a few short hairs present on genae; fore part including mandibles nearly as long as elytra. Head rather elongated, much longer than wide, sub-tubiform; genea slightly and gradually narrowed posteriorly, frontal furrows uncompleted, effaced posteriorly, presence of two pairs of frontal setiferous pores; mandibles thin and elongated, feebly curved apically, right mandibular teeth bidentate; mentum and submentum fused, mental tooth simple, base of mentum distinctly concave, submentum 8-to 10-setose. Prothorax evidently wider than head, propleura distinctly convex and evidently visible from above; pronotum sub-quadrate, slightly wider than head, evidently longer than wide, presence of two pairs of lateromarginal setae, side margins slightly or strongly sinuate before hind angles which are more or less broadly lobed. Elytra sub-ovate, much wider than prothorax, shoulders rounded, prehumeral borders arcuate or nearly oblique, lateral margins ciliate in basal half; striae lacking though somewhat traceable; presence of two dorsal pores and the preapical pore on each elytron. Chaetotaxy: the 1 st pore in the humeral group of the marginal umbilicate series transversely and backwardly shifted, at level behind the 2 nd pore; the 5 th and 6 th pores in the middle group close to each other. Protibia smooth, without longitudinal sulcus; only the 1 st protarsomere modified in male. Abdominal ventrite VII bisetose in male, while quadrisetose in female. Male genitalia weakly sclerotized, very small, slightly curved ventrally in lateral view, with a quite large sagittal aileron; apical lobe broad in dorsal view; parameres moderately developed, each with 4 rather short apical setae.
Discussion. Though Guiaphaenops is more or less similar to the genus Guizhaphaenops, the peculiar characteristics such as propleura of prothorax convex and visible from above and the 1 st pore of elytral marginal umbilicate series transversely and backwardly suggest that it has to be isolated from the latter genus (Uéno, 2006). Guiaphaenops is probably closer to Zhijinaphaenops Uéno & Ran, 2002 than to Guizhaphaenops in a strict sense because the above mentioned morphological features of Guiaphaenops are also shared by Zhijinaphaenops. However, Guiaphaenops is easily distinguished from the latter genus by its glabrous and smooth body (wholly pubescent in Zhijinaphaenops), roundly lobed hind angles (well-marked in Zhijinaphaenops), presence of anterior frontal pores on head and hind latero-marginal setae on pronotum (both absent in Zhijinaphaenops), and sub-ovate elytra (elongated ovate in Zhijinaphaenops).

Diagnosis.
A larger species, latero-margins of pronotum strongly sinuate before hind angles which are distinctly lobed and reflexed (Fig. 3a); the 1 st pore of the humeral set of umbilicate pores at level before anterior dorsal pore, while the 7 th pore behind the level of the preapical pore (Fig. 4a); the median lobe of aedeagus a little slenderer, with apical lobe narrowly constricted towards apex in dorsal view (Fig. 5a, b).
Yellowish brown, with pale appendages. Moderately shiny. Body smooth and glabrous, except genae, underside of head and prosternum each with several sparse setae, ventrites IV-VI with a few short setae between paramedian setae. Microsculptural engraved meshes finely transverse striated.
Legs thin and rather long, the 1 st tarsomere as long as the 2 nd -4 th tarsomeres together in fore, but longer in middle and hind legs.
Etymology. Dedicated to Dr. Thierry Deuve of the National Museum of Natural History, Paris, a well-known carabidologist who has described many new ground beetles of China.
Distribution. China (Guangxi) (Fig. 1c). Known only from the limestone cave near Yangli, Jiayou, Lingyun Xian. This cave opens at bottom of a hill near Yangli Cun on the right side of the road from Lingyun to Leye. It is short cave and the large part inside was dry. The single type specimen was collected in a small wet area. Other cave animals observed in this cave were millipedes, crickets and bats.   Deuve, 2002 Figs 1, 3b, 4b, 5c, d Guiaphaenops lingyunensis Deuve, 2002: 518 (type locality: Cave Shen Dong); Uéno, 2006: 24 Diagnosis. A smaller species, latero-margins of pronotum slightly sinuate before hind angles (Fig. 3b); elytra with prehumeral borders broadly arcuate, the 1 st pore of the humeral set of umbilicate pores at level behind anterior dorsal pore, while the 7 th pore before level of the preapical pore (Fig. 4b); the median lobe of aedeagus slenderer and more elongated than in G. deuvei sp. n., with apical lobe thinner in dorsal view (Fig. 5c, d). Distribution. China (Guangxi). Known from three caves (Shen Dong, Mi Dong and a cave near Dazai Tun) in Lingyun Xian (Deuve 2002;Uéno 2006) (Fig. 1a, b, d).

Guiaphaenops lingyunensis
Mi Dong is located at about one kilometre from Mawang Cun, in a valley below the main road from Lingyun to Leye. It opens above a path from the village to Sha Dong, a deeper and larger cave nearby. It is short, after 20 m from the entrance there is a large and complete dark room of 30-50 m in diameter. Majority part of this room was muddy or wet. The two beetle specimens were found quickly running on the wet ground. Other cave animals observed in Mi Dong were two species of millipedes and a bat.