Brachytrycherus denticulatus Chang & Bi sp. nov. Figs 5, 6, 7, 8, 9

Type material.

Holotype (Fig. 5), male, Guangxi, Jinxiu, Guangxi Dayaoshan Nature Reserve Bureau Yinshan Protection Station, 13.VIII.2015, Ling-Xiao Chang leg. (MHBU). Paratypes (Fig. 6), 1 female, same data as holotype (BJMNH); 1 female, Guangxi, Damingshan, Hao-Yu Liu & Ji-Bin Liang leg. (MHBU); 1 male, Guangxi Prov., Jinxiu County, 16 km, 29.VII.2011, alt. 882-950 m, PENG Zhong leg. (dissected, SHNU); 1 male, Guangxi Prov., Damingshan, Tianping Protect Station, N23.49811, E108.43715, 1230 m, 22.V.2011 N, Xing-Lei Huang Coll. (IZCAS); 1 female, same data except 28.V.2011 (IZCAS); 1 male, Guangxi, Jinxiu, Jiuwanshan, 4.VIII.2015 N, Ling-Xiao Chang leg. (CCLX); 1 male, Guangxi, jinxiu, Yinshan Protection Station, 27.VIII.2016, Yu-Yang Lei leg. (CCLX); 1 male, Guangxi, jinxiu, Dayaoshan, 22-24.IV.2018, Chun-Fu Feng leg. (CCLX); 6 males, 5 females, Guangxi, Damingshan, 1200 m, 28-31.VII.2012, Wen-Xuan Bi leg. (CBWX); 1 male, 1 female, Guangxi, Damingshan, 1200 m, 31.VII.2012, Xiao-Bin Song leg. (CBWX); 1 female, Guangxi, Jinxiu, Yinshanbaohuzhan, 1200 m, 9.VII.2014, Xiao-Bin Song leg. (CBWX); 2 males, 2 females, same data except 10.VII.2014 (CBWX); 1 male, Guangxi, Jinxiu, Laoshanlinchang, 850 m, 18.VII.2014, Xiao-Bin Song leg. (CBWX); 1 male, Guangxi, Nanning, Wuming, Damingshan, N23.49944, E108.44154, 1204 m, 7.VIII.2011, Hai-Tian Song leg. (CSHT).

Etymology.

The name refers to the mesotibia serrulated on inner edge in male.

Diagnosis.

Brachytrycherus denticulatus resembles B. convexus in the elytra being strongly convex; posterior elytral maculae transverse, dentate; hind wing reduced to narrow straps. Antenna with club rather narrow (vs. broad in B. convexus); B. denticulatus pronotum sides strongly curved (vs. weakly rounded and somewhat convergent basally); elytron widest near 1/2 length of elytron (vs. beyond mid-length). Brachytrycherus denticulatus is extremely similar to B. humeralis sp. nov. in appearance, but the humeri (Fig. 7A) are not distinctly prominent, protibia in male with small sharp tooth near apical 1/4 on inner edge, and mesotibia serrulated on inner edge in male can distinguish B. denticulatus from B. humeralis .

Description.

Length 10.2-13.7 mm, width 5.7-6.9 mm. Body broadly oval, approximately 1.8-2.0 times as long as wide; strongly convex; shiny. Colour black with two red-brown maculae on each elytron.

Head. Antenna (Fig. 8A) long and slender, nearly 1/2 body length, with antennomeres 1-8 distinctly longer than wide; scape approximately 4.0 times as long as pedicel; antennomere 3 nearly as long as 4 and 5 combined; antennomere 4 as long as 5, antennomeres 5-8 gradually shorter; club composed of three antennomeres, narrow and moderately flat. Maxilla with terminal palpomere elongate, almost 2.0 times as long as palpomere 3, tapering anteriorly, truncate apically.

Thorax. Pronotum (Fig. 8B) 2.6-3.3 mm long, 4.4-5.4 mm wide; widest behind 1/2 of pronotal length; surface opaque; lateral margins narrowly bordered, sides strongly curved; front angles produced anteriorly, bluntly round; disc weakly convex, with two large round raised areas laterally; transverse wrinkle laterally; median furrow distinct, straight; lateral sulci linear, curved, deep, extending to 1/2 of pronotal length; basal sulcus nearly straight, deep. Prosternal process (Fig. 8C) moderately separates the procoxae, slightly extending beyond coxae; sides curved outwardly, round apically. Mesoventral process (Fig. 8D) transverse, lateral margins barely widening apically, overlapping part of mesocoxae; posterior margin rather straight.

Elytra (Fig. 8G) 7.4-9.3 mm long, 1.3 times as long as wide; 2.8 times as long as and 1.3 times as wide as pronotum, sides curved, widest near 1/2 length of elytron; densely and moderately coarsely punctate; humeri not prominent. Each elytron with two transverse, irregularly shaped red-brown maculae. Anterior elytral macula bowtie-shaped, located behind humerus, its anterior and posterior margins broadly U-shaped and deeply emarginate. Posterior macula crown-shaped, located at apical 1/3, its anterior margin tridentate, posterior margin widely U-shaped and deeply emarginate. Protibia (Fig. 8E) in male with small sharp tooth near apical 1/4 on inner edge, in female without tooth; mesotibia (Fig. 8F) serrulated on inner edge in male, not serrulated in female. Hind wing (Fig. 8I) reduced to narrow straps, oval shape apically, no longer than the elytra.

Ventrite V (Fig. 8H) with lateral margins gently converging posteriorly; posterior margin in male with some small lateral tubercles, one raised area medially; in female ventrite V with posterior margin simple, weakly emarginate medially. Male genital segment (Fig. 8J) with paired apophyses fused along nearly 1/3 of its length basally; dorsal plate undivided; additional, internal, V-shaped sclerite present.

Aedeagus (Fig. 8K, L) rather long, heavily sclerotized, straight. Median lobe branched apically; branch moderately long and rather straight, flat and round apically. Tegmen placed basally, comparatively large, ring-shaped; parameres rather large, rectangle, fused with tegmen.

Biology and ecology.

The adults were collected by hand collected from a large pile of dead bamboos in the day (Fig. 9).