A review of the genus Brachytrycherus Arrow (Coleoptera, Endomychidae) of mainland China with descriptions of three new species

Abstract This paper presents a review of the genus Brachytrycherus Arrow from mainland China. Three new species are described and illustrated: B. bipunctatus Chang & Bi, sp. nov., B. denticulatus Chang & Bi, sp. nov., and B. humeralis Chang & Bi, sp. nov. The diagnosis, distribution, type locality, biology, and ecology are provided for each species. A key to the species of Brachytrycherus known in China is updated.


Introduction
established Brachytrycherus for two new species from India, B. perotteti and B. madurensis. This genus belongs to the largest endomychid subfamily Lycoperdininae. In 2005, Brachytrycherus was placed in the Amphisternus-group with seven other genera by Tomaszewska (2000Tomaszewska ( , 2005, based on the following characters: mesoventrite with intercoxal process widened laterally towards apex, overlapping parts of coxae, elytra with basal margins thickened and raised, mandible with apical tooth widely chisel-shaped, and male genital segment with an additional internal V-or U-shaped sclerite. gus was boiled in 10% NaOH solution, cleaned, and finally dissected in distilled water.
Description. Length 7.6-8.2 mm, width 4.1-4.2 mm. Body oval, approximately 2.0 times as long as wide; moderately convex; shiny. Colour black with three yellow maculae on each elytron.
Biology and ecology. The holotype was hand collected by simple searching, as it is active under the fallen decayed wood in the day (Fig. 4). 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.
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.
Biology and ecology. The adults were collected by hand collected from a large pile of dead bamboos in the day (Fig. 9).  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 ( 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.
Biology and ecology. The adults were collected by hand collected from a large pile of dead bamboos at night (Fig. 13).

Distribution. China (Xizang).
Biology and ecology. Almost all individuals were found active on fence, woodpile or timber piles within the village and its surrounding area at night (Fig.16D, E)). Some larvae and adults were found (sometimes at the same time) feeding on the surface of the perithecia or spores of Daldinia concentrica (Xylariaceae) (Fig. 16D), seeming to prefer the asexual phase; however, individuals were also found on mature ascocarps (Chang et al. 2016).

Brachytrycherus curviantennae
Length. 8.5-9.4 mm; width: 5.1-5.2 mm.   Biology and ecology. The male was hand collected by simple searching, as it is active on branches at night (Fig. 16C). Two females were collected by shaking the tree from a large clump of dead wood of Fagaceae plants (Fig. 16A) (Chang et al. 2016).
Thorax. Pronotum 2.1-2.2 mm long, 3.5-4.2 mm wide; widest near 1/2 of pronotal length; finely and densely punctate; lateral margins rather narrowly bordered, sides undulate; front angles produced anteriorly, rather acute; disc weakly convex, two small round raised area laterally; transverse wrinkle and inflexed laterally; median furrow shallow, extending to 1/2 length of pronotum; lateral sulci linear, deep, extending to basal 1/3 length of pronotum; basal sulcus weakly undulate, deep. Prosternal process moderately separates procoxae; not extending beyond coxae; sides nearly parallel, expanded apically; posterior margin in male truncate and emarginate in female. Mesoventral process transverse, lateral margins weakly widening apically and overlapping part of mesocoxae; posterior margin nearly straight. Elytra 6.3-7.3 mm long, 3.0-3.3 times as long as pronotum and 1.2-1.3 times as wide as pronotum, sides curved, widest near 1/2 length of elytron; finely and densely punctate; humeri prominent. Each elytron with three irregular orange-red maculae. Anterior two elytral maculae located near basal 1/4, lateral maculae oval, almost confined to umbo; medial macula nearly round, larger than lateral one, sometimes narrowly connected. Posterior macula located near apical 1/4, weakly transverse, nearly cloud-form, outer sides far from elytral lateral margin, inner margin of macula far from   elytral suture. Protibia in male with rather long sharp tooth near 1/2 length on inner edge, in female without tooth; mesotibia in male with small sharp tooth behind 1/2 length on inner edge, and then abruptly curved to apex, in female without tooth.
Distribution. China (Guangxi), Laos, Vietnam (Tonkin). First records from China. Type locality. Lectotype: Laos, 1 male; Syntype: Vietnam (Tonkin), 1 male. Biology and ecology. The adults were found active and feeding on the mould growing on dead bamboos at night (Fig. 18). The adults and larvae were brought back and placed in artificial conditions to rear. The last instar larvae pupated on surface of dead bamboos, from their pupal stage to matured to adults in approximately seven to nine days (Fig. 19).

Discussion
The genus Brachytrycherus belongs to the Amphisternus group of Lycoperdininae; the monophyly of this group was defined by Tomaszewska (2005), based on shared characteristics. However, in some specimens (both new species and B. femoralis) the mesoven-  trite intercoxal process sides are weakly widened apically. The shape of the mesoventrite intercoxal process is not stable; thus, it may not be appropriate as a character used to defined the Amphisternus group. The unique character for Brachytrycherus is a sexual dimorphism in the shape of the prosternal process in some species: for example, the prosternal process in male B. bipunctatus sp. nov. is very narrow, the sides are weakly curved outwardly, rounded apically; females are wider than males, the sides are nearly straight, and weakly truncate apically. This character is observed for the first time in the Endomychidae.