Brachytrycherus Arrow, 1920

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 Arrow, 1920

Brachytrycherus Arrow, 1920: 12.

Type species.

Brachytrycherus perotteti Arrow, 1920.

Diagnosis.

As stated in Chang et al. (2016), species of Brachytrycherus resemble those of Ohtaius Chûjô and Gerstaeckerus Tomaszewska in having the body black or blackish brown, elytral maculae transverse, most often orange or yellow. These genera share the feature of having the mandibles chisel-shaped apically. However, Brachytrycherus can be distinguished from these genera by the following combination of characters: 1) body less elongate; 2) head with well-developed gular sutures; 3) mesoventral process with sides parallel; 4) maxillary lacinia with tuft of S-like setae apically ( Tomaszewska 2005).

Description

(based on Tomaszewska 2005). Body squat-oval to oval, moderately convex to strongly convex, glabrous or minutely pubescent. Colour dark brown to black, usually with orange or yellow markings on elytra.

Head with gular sutures well developed, widely separated, convergent apically. Antennae ( Fig. 20 A–C ) 11-segmented, long and slender or rather stout; antennal club 3-segmented, loose. Mandible with chisel-shaped apical tooth and moderately large subapical tooth. Maxilla with terminal palpomere longer than wide, tapering apically; lacinia with tuft of S-shaped apical spines.

Pronotum transverse, widest near 1/2 of pronotal length or apical 1/3; anterior edge with rater large stridulatory membrane; sides weakly undulate or strongly curved. Prosternal process ( Fig. 21 A–C ) not extending beyond coxae; narrowly separates procoxae, sides weakly curved outwardly or nearly straight, rounded, weakly truncate or emarginate apically. Mesoventral process ( Fig. 21 A–C ) transverse, lateral margins widening apically and overlapping parts of coxae. Elytra anterior edge thickened and raised; sides curved, widest near 1/2 length of elytron; most often with contrasting markings. Tibiae ( Fig. 22 A–C ) most often with sexual characters, in male with different degrees of concavity, curved or tooth.

Abdomen in both sexes with five ventrites. Ventrite V ( Fig. 23 A–C ) almost always with sexual characters, posterior margin in male weakly curved or rounded medially, and/or with longitudinal short wrinkles laterally. Male genital segment with paired apophyses fused along nearly 1/3 of its length basally; dorsal plate undivided; additional, internal, V-shaped sclerite present.

Aedeagus ( Fig. 24 A–C ) rather long, heavily sclerotized, without basal curvature. Median lobe branched apically. Tegmen placed basally, ring-shaped, fused with parameres.

Distribution.

Oriental Region (India, Laos, Thailand, South of China).

Figures

Figure 20. Left antenna of Brachytrycherus. A B. conaensis B B. curviantennae C B. femoralis.

Figure 21. Prosternal and intercoxal processes of males. A B. conaensis B B. curviantennae C B. femoralis.

Figure 22. Abdomen with ventrite V of males. A B. conaensis B B. curviantennae C B. femoralis.

Figure 23. Left tibia of Brachytrycherus (male). A B. conaensis B B. curviantennae C B. femoralis; 1 protibia; 2 mesotibia; 3 metatibia.

Figure 24. Aedeagus of Brachytrycherus. A B. conaensis B B. curviantennae C B. femoralis; 1 lateral view; 2 apical view. Scale bars: 1 mm.