Stenothemus cou Hsiao, 2015, sp. nov.

Stenothemus cou sp. nov.

Figs. 4–5, 10–13

Type material. Holotype ♂, Tatachia, Nantou, Taiwan, 17. XI. 2009, C.-F. Lee leg. (TARI). Paratypes: 4 ♂, same data as for the holotype (TARI); 4 ♂, 5 ♀, same locality, 29. XII. 2009, C.-F. Lee leg. (TARI); 14 ♂, 5 ♀, SE of Alishan, 2300m, 23°28’20N 120°51E, Nantou / Chiayi Co., Taiwan, 6–8.XI. 2008, L. Dembický leg. (BMNH); 1 ♀, Tefuyeh Historic Trail, Alishan, Chiayi, 14. XII. 2013, S.-Y. Shih leg. (YHC).

Description. Male (Fig. 4). Eyes black. Head and prothorax dark red to brown, pronotum with anterolateral parts and posterior margin yellowish brown to honey yellow. Antennae fuscous to brown, with basal part of each antennomere light yellow. Mandibles yellowish brown, with apices darker; maxillary and labial palpi yellowish brown. Coxae, trochanters and basal part of femora light brown; femora, apical parts of tibiae and tarsi fuscous to brown; tibiae and claws yellowish brown. Elytra yellowish brown, disc with several round black spots. Body densely covered with fine yellowish pubescence; anterior margin of clypeus fringed with pale bristles; antennae, elytra and legs with some brownish bristles intermingled with primary pubescence.

Head as long as wide, eyes moderately protruding, ratio of an eye diameter to interocular space 1:3.10, dorsum slightly swollen on posterior part, depressed along the anterior margin of clypeus and in lateral areas before eyes; anterior margin of clypeus arcuate and slightly emarginated in middle; surface densely and finely punctate, each side with a rectangular impression behind antennal socket; antennae extending to apical third length of elytra, antennomere I clavate, II short and expanded apically, III to XI subcylindrical, ratio of the lengths of antennomeres I to XI as follows: 16.5:10:14:17:17.5:17.5:17:17.5:17:14:14.5.

Pronotum subquadrate, moderately narrowed posteriorly, nearly as wide as head, about 0.95 times as long as wide; anterior margin almost straight; posterior margin arcuate, but feebly indented in middle; lateral margins feebly arcuate, constricted before posterior angles; anterior angles rounded; posterior angles slightly protruding and obtuse; disc swollen, with a pair of rounded elevations at posterolateral parts; antero-lateral areas hollowed; mediolongitudinal furrow distinct in central area; surface matt, finely and sparsely punctate. Scutellum triangular with rounded apex.

Elytra conjointly at maximal width about 1.7 times as wide as pronotum, about 2.8 times as long as wide, lateral margins subparallel in basal one-fifth, diverging posteriorly and widest at apical forth; surface densely and coarsely punctate, but fine and sparse in anteriorly.

Prosternal process concave at the apex. Mesoventrite obviously convex along the middle line. Legs moderately slender; femora mostly straight; tibiae somewhat bent.

Aedeagus (Figs. 10–12): ventral process of each paramere clavate and slightly bent inwards at apical part; dorsal plate of each paramere widely separated from each other, with the apex moderately curved outwards; each laterophyse bent dorsad with pointed apex, basal part of laterophyses globular and swollen.

Length: 5.2–7.3 mm (in the holotype: 6.0); width: 1.3–1.8 mm (1.6).

Female (Fig. 5). Colour, punctation and pubescence resemble male. Body and pronotum obviously wider that than in male; head as long as wide, eyes less protruding than in male, ratio of an eye diameter to interocular space 1:3.80; antennae shorter than in male, extending to elytral midlength, ratio of the lengths of antennomeres I to XI as follows: 16.5:10:14.5:20:19:17:16:16:15.5:13.5:14.5. Pronotum about 1.10 times as wide as head, about 0.90 times as long as wide. Elytra conjointly about 1.7 times as wide as pronotum, about 2.6 times as long as wide. Seventh abdominal ventrite (Fig. 13): lateral and terminal parts densely pubescent, posterior margin rounded on both sides, forming middle lobe with obvious twin projections.

Length: 6.2–7.2 mm; width: 1.8–2.3 mm.

Variation. In some paratypes, the spots on the elytra are indistinct.

Diagnosis. This new species is very similar to S. seediq Hsiao, sp. nov. in the appearance and S. owadai Okushima & M. Satô, 1997 in the shape of the aedeagus. It can be distinguished from S. seediq sp. nov. by the slightly wider interocular space, the structure of the aedeagus, especially the curved dorsal plate and the shape of laterophyses, and the emarginate middle lobe of the female seventh abdominal ventrite. From S. owadai, it differs in the elytra with black spots, feebly arcuate lateral margins of pronotum, the structure of aedeagus, especially the widely separated and more curved laterophyses, and the obvious twin projections on the middle lobe of the female seventh abdominal ventrite.

Biological notes. This new species is distributed from Sinyi Township to Alishan Township at an altitude about 2300 meters, and appears mainly in November and December. Stenothemus cou could be sympatric with S. owadai because some specimens examined from BMNH and TARI have the same label data as the type series of S. cou.

Etymology. The specific name is given in honor of the Cou Taiwan Indigenous People who live in south central Taiwan, especially in Alishan Township and Sinyi Township where S. cou is mainly distributed.

Distribution. South-central Taiwan (endemic).