Brachytrycherus denticulatus 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 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 ).

Figures

Figure 5. Habitus of B. denticulatus sp. nov. (male). A dorsal view B ventral view C lateral view. Scale bars: 2 mm.

Figure 6. Habitus of B. denticulatus sp. nov. (female). A dorsal view B ventral view. Scale bar: 2 mm.

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

Figure 8. B. denticulatus sp. nov. A antenna B pronotum C provenrite 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 9. Habitats of B. denticulatus sp. nov.