Brachytrycherus humeralis Chang & Bi sp. nov. Figs 10, 11, 12, 13

Type material.

Holotype (Fig. 10), male, Guangxi, Huanjiang, Yangmeiao Protection Station, 4.VIII.2015 N, Ling-Xiao Chang leg. (MHBU). Paratypes (Fig. 11), 1 female, same data as holotype (BJMNH); 1 male, same data as holotype (CCLX); 1 male, Guangxi, Damingshan, Longteng, Power Station, N23.49811, E108.43715, 1230 m, 20.V.2011 N, Xing-Lei Hhang leg. (IZCAS); 1 male, same data except dissected (IZCAS); 1 female, Guangxi, Jinxiu, Shengtangshan, 700 m, 19.V.1999, Fu-Sheng Huang leg. (I0Z(E)1172359, IZCAS). 1 male, Guangxi, Jinxiu, Yinshan, 27.VIII.2016, Yu-Yang Lei leg. (CCLX).

Etymology.

The name refers to the humeri with a distinct raised oval area.

Diagnosis.

Brachytrycherus humeralis resembles B. convexus in the elytra being strongly convex; posterior elytral maculae transverse, dentate; hind wing reduced to narrow straps. However, they can be differentiated by B. humeralis with the antennal club that is rather narrow (vs. broad); the pronotum sides are strongly curved (vs. weakly rounded and somewhat convergent basally); and the elytra are widest near 1/2 length of elytron (vs. beyond mid-length). In addition, B. humeralis is extremely similar to B. denticulatus sp. nov. in appearance. The humeri (Fig. 7B) are distinctly prominent, the protibia in males is without a tooth, raised near apical 1/3 on inner edge, and the simple mesotibia in males can distinguish B. humeralis from B. denticulatus .

Description.

Length 12.5-12.7 mm, width 6.6-7.0 mm. Body broadly oval, approximately 1.8-1.9 times as long as wide; strongly convex; shiny. Colour black with two red-brown maculae on each elytron.

Head. Antenna (Fig. 12A) long and slender, nearly 1/2 body length, with antennomeres 1-8 distinctly longer than wide; scape approximately 3.0 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 1.5 times as long as palpomere 3, tapering anteriorly, truncate apically.

Thorax. Pronotum (Fig. 12B) 2.9-3.2 mm long, 5.1-5.3 mm wide; widest 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. 12C) moderately separates the procoxae, slightly extending beyond coxae; sides curved outwardly, round apically. Mesoventral process (Fig. 12D) transverse, lateral margins weakly widening apically and overlapping part of mesocoxae, in some specimens hardly widening apically; posterior margin rather straight.

Elytra (Fig. 12G) 8.9-9.6 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 distinctly prominent. Each elytron with two transverse, irregular red-brown maculae. Anterior elytral macula bowtie-shape, located behind humeri, its anterior and posterior margin widely 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. 12E) in male raised near apical 1/3 on inner edge, in female not raised; mesotibia (Fig. 12F) simple. Hind wing (Fig. 12I) reduced to narrow straps, oval shape apically, no longer than the elytra.

Ventrite V (Fig. 12H) with lateral margins gently converging posteriorly; posterior margin in male widely raised medially; in female ventrite V with posterior margin simple, weakly emarginate medially. Male genital segment (Fig. 12J) with paired apophyses fused along nearly 1/3 of its length basally; dorsal plate undivided; additional, internal, V-shaped sclerite present.

Aedeagus (Fig. 12K, L) rather long, heavily sclerotized, distinctly curved outwardly near 1/2 of length, and with one branch, rather short and straight, weakly acute apically. Median lobe branched apically, short and straight, flat and widely round apically. Tegmen placed basally, comparatively large, ring-shaped; parameres rather large, fused with tegmen.

Biology and ecology.

The adults were collected by hand collected from a large pile of dead bamboos at night (Fig. 13).