Shuangheaphaenops elegans, Tian, Mingyi, 2017

Tian, Mingyi, 2017, A new highly cave-adapted trechine genus and species from northern Guizhou Province, China (Coleoptera, Carabidae, Trechinae), ZooKeys 643, pp. 97-108 : 101-105

Shuangheaphaenops elegans sp. n. Figs 1, 2, 3, 4, 5, 6

Holotype.

Male, Cave Mahuang Dong, Shuanghe Dong cave system, Wenquan Zhen, Suiyang County, 28°14'32"N, 107°17'24"E, 720 m, X-18-2016, leg. Wenbo Li, deposited in the insect collection of South China Agricultural University, Guangzhou, China (SCAU); additional material: an elytral debris, same cave and collecting date as above, leg. Mingruo Tang, in SCAU.

Diagnosis.

A large-sized, eyeless cave trechine beetle, highly modified in morphology, with very elongated and slender body which is about four times longer than wide, fore body about as long as elytra, antennae as long as body including mandibles, extending beyond elytral apex; body glabrous, except for basal half of pronotum which is covered with erected setae.

Description.

Length: 7.9 mm (from apex of right mandibles to elytral apex) or 7.2 mm (from labrum to elytra); width: 1.79 mm. Fore body (including mandibles) longer than elytra, (HLm+PrL)/EL = 1.07. Habitus as in Fig. 2.

Yellowish brown, a little darker on head, pronotum and basal half of elytra, pale on antennae, mouthparts, palps and tarsi. Moderately shiny. Head and elytra glabrous, pronotum glabrous on apical half (but with two or three short setae near middle of frontal margin) but pubescent on basal half. Underside of head and prothorax glabrous (Fig. 3b), abdominal ventrites sparsely pubescent. Microsculptural engraved meshes more or less isodiametric on head and elytra, but transverse striate on pronotum.

Head (Fig. 3a) elongate quadrate, much longer than wide (HLm/HW = 2.74, HLl/HW = 1.87); genae fairly developed, hardly dilated laterally, suddenly constricted posteriorly before occipital suture, making a well-marked but short neck constriction; subparallel-sided, widest at about middle from labrum to base of head; frons and vertex moderately convex, frontal furrows deep and well-marked, subparallel-sided, ended just behind the level of anterior supraorbital pores; clypeus transverse, 4-setose; labrum transverse, with frontal margin slightly protruding medially, 6-setose; anterior supraorbital setiferous pores located at about middle from frontal margin of labrum to base of head, while the posterior two pairs (which are very close to each other) at about 1/4 of head from base; palps long, slender and glabrous except for the 2nd labial palpomere which is bisetose on inner margin; the 2nd labial palpomere 1.35 times longer than the 3rd; the 3rd maxillary palpomere 1.25 times longer than the 4th; suborbital pores at about middle from base to labial suture. Antennae thin and long, the 1st antennomere stouter than other, and the shortest, the 3rd the longest; the comparative length ratio of each antennomeres as: the 1st (8.5), 2nd (11.0), 3rd (18.0), 4th (17.0), 5th (17.0), 6th (16.5), 7th (13.5), 8th (11.0), 9th (11.0), 10th (10.0) and 11th (10.5).

Prothorax shorter than head including mandibles (PrL/HLm = 0.80), but longer than head excluding mandibles (PrL/HLl = 1.17), widest at about 1/4 from base, twice as long as wide (PrL/PrW = 2.10), slightly wider than head (PrW/HW = 1.09), evidently wider than pronotum (PrW/PnW = 1.22), half as wide as elytra (PrW/EW = 0.49). Pronotum elongate, dolioform, two and half times longer than wide (PnL/PnW = 2.46), evidently narrower than head (PnW/HW = 0.89), base slightly wider than front (PbW/PfW = 1.09); lateral sides finely bordered throughout, base and front unbordered; nearly parallel-sided, fairly expanded at the widest part which is at about 3/7 from base, slightly sinuate before hind angles which are nearly rectangular, fore angle obtuse; median line well-marked, basal transversal impression very short; front slightly convex, base feebly concave. Scutellum fairly small.

Elytra (Fig. 4) elongate ovate, much longer than pronotum (EL/PnL = 2.12), about twice as long as wide (EL/EW = 2.08); distinctly dilated posteriorly, widest at about apical 3/7 of elytra, lateral sides smooth, not ciliate, finely bordered throughout; distinctly convex; striae easily traceable though devoid, intervals moderately convex. Chaetotaxy: basal pore at subequal distant from scutellum to marginal gutter; two dorsal setiferous pores present on the 3rd stria at about 1/3 and 2/3 from base respectively; the preapical pore closer to suture than to apical margin; the marginal umbilicate pores not aggregated, the 8th pore near marginal gutter, the 4th and 5th pores distant from the gutter, others intermediary located; the humeral groups separately spaced, the 1st and 4 th pores distant from the 2nd and 3rd pores respectively which are close to each other, distance from the 1st pore to the 3rd slightly shorter than that from the 2nd to 4th; the middle group widely spaced, making distance of the 5th pore and 4th subequal to that of the 5th and 6th; apical group composed of three pores.

Legs thin and long, bearing short pubescence; fore- and middle femora sparsely setose; fore tibia smooth, without longitudinal furrow or sulcus; the 1st tarsomere shorter than, as long as, and longer than the 2 nd– 4th tarsomeres together in fore, middle, and hind legs, respectively.

Male genitalia (Fig. 5): Aedeagus moderately sclerotized, quite small and short; distinctly curved at about basal 1/3 in lateral view, feebly curved toward subapex, then broadly ended at apex; inner sac armed with a fairly large copulatory piece which is about 1/4 as long as the median lobe; base moderately sized, opened ventrally; in dorsal view the apical part of aedeagus thin, slightly sinuate from middle to apex, apical lobe narrow, much longer than wide, gradually constricted towards the rounded apex. Parameres short and quite stout, right and left parameres bearing five and four long apical setae respectively.

Etymology.

To indicate the slender shape of this beautiful aphaenopsian beetle.

Distribution.

China (Guizhou: Suiyang) (Fig. 1). Known only from Cave Mahuang Dong, the type locality.

Mahuang Dong (Figs 6a, b) is one of the most important caves in Shuanghe Dong cave system ( Li et al. 2008). It is opened along the main road of the Shuanghe Dong National Geopark on north, and is about 1.2 km long. The beautiful beetle, together with the elytral debris, were collected in a small chamber of the labyrinthic part at about 100 m from the entrance. Other cave animals found also in Mahuang Dong were the semi-aphaenopsian beetle Qianotrechus tenuicollis Ueno, 1998, an amphipod, a cave cricket (Figs 6c-f), a pseudoscorpion and two millipedes.