The genus Xanthocorus can be distinguished from other genera of the tribe Chilocorini by the following combination of characters: antenna composed of 10 antennomeres, relatively slender, terminal antennomere very small and inserted in antennomere 9 (Fig. 1a); pronotal basal margin without bordering line; prosternal process narrow, without carinae (Fig. 1e); elytral epipleura distinctly oblique and without foveae; abdominal postcoxal lines semicircular, incomplete laterally (Figs 2d, 3d, 4d); front tibiae without apical spurs, mid and hind tibiae with two apical spurs (Figs 1h, 1i); tarsal claw with basal tooth (Fig. 1j).

Figure 1. 

Xanthocorus nigromarginatus (Miyatake, 1970). a antenna b mandible c labium d maxilla e prosternum f meso- and metaventrite g metendosternite h front leg i hind leg j tarsal claws. Scale bars: 0.1 mm.

Figure 2. 

Xanthocorus nigromarginatus (Miyatake, 1970). a dorsal view b lateral view c anterior view d abdomen e penis f apex of penis g tegmen, lateral view h tegmen, ventral view i female genitalia: ovipositor. Scale bars: 0.1 mm.

Figure 3. 

Xanthocorus nigrosuturalis sp. n. a dorsal view b lateral view c anterior view d abdomen e penis f apex of penis g tegmen, lateral view h tegmen, ventral view i–j female genitalia: i ovipositor j spermatheca. Scale bars: 0.1 mm.

Body broadly oval to almost circular in outline, moderately convex. Dorsum glabrous.

Head relatively large, 0.50–0.58 times pronotal width, covered with short, greyish pubescence; antenna composed of 10 antennomeres, relatively slender, scape and pedicel stout, of the same width, and pedicel distinctly shorter than scape, antennomeres 3–8 gradually broadening, antennomere 9 slightly narrower than 8, and terminal antennomere short, partially embedded in antennomere 9 (Fig. 1a). Mandible unidentate, prostheca distinct, lateral margin of mandible strongly curved (Fig. 1b). Terminal maxillary palpomere broadening apically, apical margin strongly obliquely truncate (Fig. 1d). Terminal labial palpomere stout with rounded apex (Fig. 1c).

Prothorax descending anteriorly. Base of pronotum and elytra not contiguous all along their length. Basal margin of pronotum without bordering line. Prosternum T-shaped, in front of coxae distinctly longer than basal width of prosternal process. Prosternal process narrow, parallel sided, without carinae (Fig. 1e). Mesoventrite approximately trapezoidal, mesal surface with emarginate fossa for receiving apex of prosternal process. Mesoventral process narrow; meso-metaventral process narrow, junction arcuate anteriorly, with visible suture (Fig. 1f). Metendosternite stalk as long as broad (Fig. 1g). Scutellum small,triangular. Elytra distinctly wider than pronotum at base, surface finely or coarsely punctate. Elytral epipleura distinctly oblique and without foveae. Abdomen with five ventrites in female and six ventrites in male. Abdominal postcoxal lines recurved, incomplete laterally. Front tibiae without apical spurs, mid and hind tibiae with two apical spurs (Fig. 1h, 1i); tarsal claw with basal tooth (Fig. 1j).

This species can be distinguished from other species of Xanthocorus by the following combination of characters: body almost circular, pronotum black with anterior angles and anterior margin yellow; elytra yellow, only elytral lateral margins of elytra black (Fig. 2a–c); apex of penis bifurcate, penis guide slightly asymmetrical, parameres stout (Fig. 2e–h).

TL: 5.53–5.92 mm, TW: 5.11–5.30 mm, TH: 2.80–2.88 mm, TL/TW: 1.08–1.12, PL/PW: 0.49–0.50, EL/EW: 0.97–0.99.

Body almost circular, moderately convex. Head yellow with black vertex in male, entirely black in female. Mouthparts and antennae brown, sparsely covered with short, greyish pubescence. Pronotum black, only anterior angles and anterior margin yellow. Scutellum black. Elytra yellow, only elytral bead black (Fig. 2a–c). Underside black except inner part of elytral epipleura yellow and abdominal ventrites brownish black, sparsely covered with short, greyish pubescence.

Head relatively large, 0.50 times pronotal width, punctation on frons large and densely distributed, 0.5–1.5 diameters apart, surface polished between punctation. Eyes approximately oval, densely faceted, interocular distance 0.54 times head width (Fig. 2c). Pronotum 0.54 times elytral width, pronotal punctation large and densely distributed, smaller than those on head, 1.0–2.0 diameters apart, surface polished between punctation. Punctation on elytra moderately large and densely distributed, 1.0–2.0 diameters apart, similar to those on pronotum. Prosternal process narrow with sides parallel. Posterior margin of abdominal ventrite 5 and 6 slightly emarginate medially in male (Fig. 2d).

Male genitalia: penis slender, penis capsule with short outer and inner arms, apex of penis bifurcate with membranous appendage (Fig. 2e–f). Tegmen stout with penis guide slightly asymmetrical in ventral view and widest at base with sides parallel from base to 1/2 length, then gradually converging to blunt apex in lateral view. Parameres stout, distinctly longer than penis guide, densely covered with long setae at inner surfaces and apices with group of long setae in lateral view (Fig. 2g–h).

Female genitalia: coxites distinctly elongate, approximately triangular (Fig. 2i).

China: Jiangxi Prov: 2 males and 1 female, Luofu village, Jinggangshan County, [26°65.41'N; 114°22.49'E], ca 763m, 18.ix.2004, Wang XM leg; 1 female, Jingzhu Mountain, Jinggangshan County, [26°37.95'N; 114°08.98'E], ca 1142m, 22.ix.2004, Wang XM leg.

China (Gansu, Zhejiang, Jiangxi, Fujian, Yunnan) (Fig. 5).

Figure 5. 

Distribution map. (●) Xanthocorus nigromarginatus (Miyatake, 1970); (■) Xanthocorus nigrosuturalis sp. n.; (▲) Xanthocorus mucronatus sp. n.

The Chinese specimens of this species studied were identical with the illustrations and descriptions of adult and male genitalia given by Miyatake (1970).

This species resembles Xanthocorus nigromarginatus, but can be distinguished from it by having slightly elongate body; black pronotum with only anterior angles yellow; elytra yellow with black elytral lateral margin, anterior margin and suture (Fig. 3a–c); slender parameres (Fig. 3g). In X. nigromarginatus, body almost circular, pronotum black except anterior angles and anterior margin yellow; elytra yellow, only elytral lateral margin black (Fig. 2a–c); parameres stout (Fig. 2g).

TL: 4.16–5.79 mm, TW: 3.35–4.81 mm, TH: 1.83–2.77 mm, TL/TW: 1.20–1.24, PL/PW: 0.47–0.51, EL/EW: 1.04–1.05.

Body broadly oval, moderately convex. Head and mouthparts black. Antenna brownish yellow, sparsely covered with short, greyish pubescence. Pronotum black with anterior angles yellow. Scutellum black. Elytra yellow with black elytral bead, anterior margin and suture (Fig. 3a–c). Underside black except inner margins of elytral epipleura yellow. Abdominal ventrites brown, sparsely covered with short, greyish pubescence.

Head relatively large, 0.56 times pronotal width, punctation on frons large and densely distributed, 1.0–1.5 diameters apart, surface polished between punctation. Eyes approximately oval, densely faceted, interocular distance 0.51 times head width (Fig. 3c). Pronotum 0.55 times elytral width, pronotal punctation large and moderately densely distributed, smaller than those on head, 2.0–3.0 diameters apart, surface polished between punctation. Punctation on elytra moderately large and moderately densely distributed, 2.0–3.0 diameters apart, similar to those on pronotum. Prosternal process narrow with parallel sided. Posterior margin of male abdominal ventrite 5 distinctly emarginate and ventrite 6 slightly emarginate medially (Fig. 3d).

Male genitalia: penis slender, penis capsule with short outer and inner arms. Apex of penis bifurcate with membranous appendage (Fig. 3e–f). Tegmen stout with penis guide distinctly asymmetrical in ventral view and with sides parallel from base to 2/3 length, then abruptly converging to blunt apex in lateral view. Parameres slender, strongly constricted at base, expanded toward apex, distinctly longer than penis guide, densely covered with long setae at inner surfaces and apices with group of long setae in lateral view (Fig. 3g–h).

Female genitalia: coxites distinctly elongate, approximately triangular (Fig. 3i). Spermatheca C-shaped, cornu without appendage (Fig. 3j).

Holotype. male, China: Shannxi Prov: Daguping and Xihe Conservation Station, Foping National Nature Reserve, No. SCAU (E) 11475, [33°35.57'N; 107°50.25'E], ca 1428m, 22.vii.2009, Wang XM leg (SCAU). Paratypes. 1 male and 1 female with same data as holotype (1 female in SCAU, 1 male in IOZ); Sichuan Prov: 7 females, Mamize village, Leibo County, [28°25.02'N; 103°36.13'E], ca 2600m, 19–20.ix.2007, Liang JB leg (SCAU); 2 females, Dafengding National Nature Reserve, Meigu County, [28°60.77'N; 103°23.72'E], ca 2400m, 21.ix.2007, Chen XS leg (SCAU); 2 males and 1 female, Liziping National Nature Reserve, Shimian County, [29°09.89'N; 102°33.84'E], ca 2000m, 26–27.ix.2007, Chen XS leg (2 males in SCAU, 1 female in IOZ). Hubei Prov: 1 male and 1 female, Banqiao Conservation Station, Shennongjia National Nature Reserve, [31°45.90'N; 110°37.02'E], ca 1170m, 21–24.vii.2007, Wang XM leg (SCAU); 4 females, Guanmenshan Scenic Spot, Shennongjia National Nature Reserve, [31°42.94'N; 110°36.53'E], ca 1260m, 2.viiiI.2007, Chen XS leg (SCAU).

China (Hubei, Sichuan, Shannxi) (Fig. 5).

The species name is derived from Latin and refers to the black elytral suture.

This species is similar to Xanthocorus nigrosuturalis sp. n., but can be distinguished from it by having lateral margins of elytra yellow (Fig. 4a) and apex of penis pointed (Fig. 4f). In X. nigrosuturalis sp. n., elytral lateral margin is black (Fig. 3a) and penis has blunt and bifurcate apex (Fig. 3f).

TL: 3.75 mm, TW: 2.98 mm, TH: 1.62 mm, TL/TW: 1.27, PL/PW: 0.49, EL/EW: 1.01.

Body broadly oval, moderately convex. Head black except sides of clypeus yellow. Mouthparts black. Antenna brown, sparsely covered with short, greyish pubescence. Pronotum black with anterior angles yellow. Scutellum black. Elytra yellow with black suture (Fig. 4a–c). Underside black except elytral epipleura yellow, sparsely covered with short, greyish pubescence.

Head relatively large, 0.58 times pronotal width, punctation on frons fine and moderately densely distributed, 2.0–3.0 diameters apart, surface polished between punctation. Eyes approximately oval, densely faceted, interocular distance 0.55 times head width (Fig. 4c). Pronotum 0.55 times elytral width, pronotal punctation fine and sparsely distributed, smaller than those on head, 3.0–4.0 diameters apart, surface polished between punctation. Punctation on elytra moderately fine and sparsely distributed, 2.0–3.0 diameters apart, similar to those on pronotum. Prosternal process narrow with sides parallel. Posterior margin of abdominal ventrite 5 and 6 distinctly emarginated medially in male (Fig. 4d).

Male genitalia: penis slender, penis capsule with short outer and inner arms. Apex of penis strongly narrow with membranous appendage (Fig. 4e–f). Tegmen stout with penis guide with parallel sided from base to 1/2 length, then gradually converging to blunt apex in ventral view; in lateral view, penis guide widest at base, gradually constricted to apex. Parameres strongly constricted at base and expanded toward apex, longer than penis guide, densely covered with long setae at the inner sides and distal end with a group of long setae in lateral view (Fig. 4g–h).

Female genitalia: unknown.

Holotype. male, China: Yunnan Prov: Shangri-La, No. 20051215051, [27°90.22'N; 99°63.37'E], ca 3450m, 3.ix.2005, Wang XM leg (SCAU).

China (Yunnan) (Fig. 5).

The species name is derived from Latin and refers to the pointed apex of penis.