Brachytrycherus humeralis Chang & Bi

Chang, Ling-Xiao, Bi, Wen-Xuan & Ren, Guo-Dong, 2019, A review of the genus Brachytrycherus Arrow (Coleoptera, Endomychidae) of mainland China with descriptions of three new species, ZooKeys 880, pp. 85-112 : 85

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 ).

Figures

Figure 7. Humeri. A B. denticulatus sp. nov. B B. humeralis sp. nov.

Figure 10. Habitus of B. humeralis sp. nov. (male). A dorsal view B ventral view C lateral view. Scale bars: 2 mm.

Figure 11. Habitus of B. humeralis sp. nov. (female). A dorsal view B ventral view. Scale bar: 2 mm.

Figure 12. B. humeralis sp. nov. A antenna B pronotum C proventrite D meso- and metaventrites E male protibia F male mesotibia G elytron H male ventrite V of abdomen I hind wing J male genital segment K aedeagus in lateral view L aedeagus in apical view. Scale bars: 1 mm.

Figure 13. Habitats of B. humeralis sp. nov. A large pile of dead bamboos in Guangxi, China B adult of B. humeralis sp. nov.