Two new species of the Stenochinus amplus species-group from China (Coleoptera, Tenebrionidae, Stenochiini)

Abstract Two new species of the Stenochinus amplus species-group are described, S. apiciconcavus sp. n. (CHINA: Shaanxi) and S. xinyicus sp. n. (CHINA: Guangdong). Also, some new distribution data are provided for S. cylindricus (Gebien, 1914), and a key to the seven species of the S. amplus species-group from China is given.


Material and methods
Specimens were examined under a Nikon (SMZ800) dissecting microscope. Measurements were taken and photographs captured using a Leica (M205 A) dissecting microscope. The habitus photos were taken with a Canon (EOS 5D mark II) camera.
The measurements were as follows: body length: length of the body from the anterior edge of the clypeus to elytral apex with the head in its natural position; body width: length of the maximal elytral width; pronotal length: length of the pronotum along the midline; elytral length: length of the elytra from the base of the scutellum to the elytral apex along the suture. All measurements are given in millimeters.
The following codens of the collections are used:

Stenochinus amplus species-group
Diagnosis. Body covered with distinct scale-like hairs, mandibles subtruncate, apical projections of pronotum not or hardly reaching anterior margins of eyes, tibiae with rows of suberect hairs along inner margins, male genitalia widened basally.

Key to the species of Stenochinus amplus species-group in China
Etymology. The specific name is derived from the Latin apici [apex] + concavus [concave], a reference to the pronotum with an emargination in middle of anterior margin.
Description. Male (Fig. 17). Body length 10.3 mm, elongate, subcylindrical. Head, elytra and legs dark reddish brown, antennae reddish brown, pronotum dark brown. Scale-like hairs on the surface pale golden. Head transversely subelliptical, surface densely punctate; clypeus truncate at anterior margin, clypeogenal suture grooved, frontoclypeal suture invisible; genae weakly raised, with rounded outer margins; frons wide, distance between eyes 2.56 times as wide as transverse diameter of an eye in dorsal view. Eyes medium-sized, weakly protruding, each side with a groove along inner and posterior margins. Antennae (Fig. 7) clavate, antennomeres VIII-XI each wider than long, antennomeres XI ovate, ratio of the length of antennomeres II-XI as 0.12: 0.18: 0.09: 0.09: 0.07: 0.08: 0.07: 0.10: 0.08: 0.22. Maxillary palpomere IV strongly expanded. Pronotum (Fig. 1) 1.13 times as long as wide, widest in middle; anterior margin with a distinct emargination in middle; posterior margin weakly bisinuate, with deep emar- gination in middle; both sides steeply inclined downward, lateral margins sinuate before posterior angles; anterior angles acute and directed anteriad, posterior angles acute and directed postero-laterad; disc subelliptically projecting in anterior parts, this projecting area distinctly impressed, surface roughly and deeply punctuate, punctures often fused with one anonther. Scutellum subrectangular, glabrous. Elytra 2.5 times as long as wide, widest at apical 1/3, 2.76 times as long as and 1.25 times as wide as pronotum; dorsum convex but flattened in lateral view; disc with rows of subquadrate punctures, which are larger and deeper anteriorly, each puncture with a granule on each lateral margin; intervals somewhat transversely wrinkled, weakly ridged in lateral parts, scale-like hairs on the intervals shorter than those on pronotum. Ventral side covered with dense punctures and scale-like hairs, which distinctly shorter than those on pronotum. Legs relatively short, ratio of the lengths of metatarsomeres I-IV as 0.45: 0.24: 0.17: 0.69. Male genitalia (Figs 11-12)  Diagnosis. This new species is similar to S. cylindricus, but can be distinguished from the latter by antennomeres VII-XI wider than long, pronotum moderately projecting anteriorly (Fig. 5), shape of male genitalia different (Figs 13-16) (in S. cylindricus, antennomeres VIII-XI wider than long (Fig. 10), pronotum strongly projecting anteriorly (Fig. 6)).
Etymology. The specific name is derived from the type locality of this species. Description. Male (Fig. 18). Body length 11.0 mm, elongate, subcylindrical. Head, elytra, legs reddish brown, pronotum brown, antennae and mouthparts yellowish brown; scale-like hairs surface pale golden. Head transversely subelliptical, surface densely punctate; clypeus transverse, weakly convex in middle, clypeogenal suture grooved, frontoclypeal suture invisible; genae weakly raised; frons wide, distance between eyes 2.53 times as wide as the transverse diameter of an eye in dorsal view. Eyes medium-sized, weakly protruding, with groove along inner and posterior margins. Antennae (Fig. 8) clavate, antennomeres VII-XI wider than long, antennomeres XI oval, length ratio of antennomeres II-XI as 0.16: 0.17: 0.12: 0.10: 0.09: 0.09: 0.10: 0.13: 0.10: 0.23. Maxillary palpomere IV moderately expanded. Pronotum (Fig. 2) 1.14 times as long as wide, widest shortly before middle; anterior margin weakly reflexed; posterior margin weakly bisinuate, with deep emargination in middle; both sides steeply inclined downward, lateral margins sinuate before posterior angles; anterior angles acute and directed anteriorly, posterior angles obtuse and punctures, each puncture with a granule on each lateral margin; intervals somewhat transversely wrinkled, scale-like hairs shorter and narrower than those on pronotum. Ventral side covered with dense punctures and scale-like hairs, which shorter than those on pronotum. Legs relatively short, length ratio of metatarsomeres I-IV as 0.40: 0.33: 0.21: 0.67. Male genitalia (Figs 13-14) strongly curved in middle in lateral view, 2.29 mm long, 0.43 mm wide; apicale 0.77 mm long, weakly curved in lateral view.