Arcifrons arcifrontalis Ding & Yang, 1986, by original designation.

The genus is readily distinguished from other genera in the tribe Tropidocephalini by the following features: frons distinctly sharply pointed at apex in dorsal view (Figs 1, 3, 5) and distinctly inclined anteriorly in lateral view (Figs 2, 4, 7), with median carina distinctly developed (Fig. 6); postclypeus with median carina distinct (Fig. 6).

Figures 1–4. 

Arcifrons arcifrontalis Ding & Yang, 1986. 1 male habitus, dorsal view 2 the same, lateral view 3 female habitus, dorsal view 4 the same, lateral view. Scale bars: 0.5 mm.

Figures 5–15. 

Arcifrons arcifrontalis Ding & Yang, 1986. 5 head and throad, dorsal view 6 frons and clypeus 7 the same, lateral view 8 tegmen 9 male genitalia, posterior view 10 the same, lateral view 11 aedeagus 12 genital style, posterior view 13 the same, left lateral view 14 female genitalia, posterior view 15 gonapophysis IX. Scale bars: 0.2 mm (5–10, 14, 15); 0.1 mm (11–13).

The distinctive characters used by Ding (2006) are modified as follows.

Head including eyes narrower than pronotum. Vertex broad transversely, with basal compartment near trapezoidal (Fig. 5). Frons elongate, rectangular, longer in middle line than wide at widest part, lateral carinae subparallel, median carina distinctly developed, forked at base (Fig. 6), with distinctly sharply pointed at apex in dorsal view (Fig. 5) and distinctly inclined anteriorly in lateral view, with apical margin roundly convex (Fig. 7). Postclypeus with median carina distinct, lateral carinae absent, width at base slightly wider than frons at apex. Antennae short, cylindrical, reaching to frontoclypeal suture, with basal segment with length longer than width, shorter than second segment (Fig. 6). Pronotum longer than vertex, tricarinae distinct, lateral carinae reaching hind margin, with base curved inward, with posterior apex more closed anterior apex of lateral carinae of mesonotum. Mesonotum developed, tricarinae distinct, median carina complete, reaching tip of scutellum, lateral carinae reaching hind margin (Fig. 5). Spinal formula of hind leg 5-6-4. Hind tibiae with a lateral tooth basally and medially respectively. Post-tibial spur without teeth along hind margin, but with a small apical tooth, with inner side surface concave.

Anal segment (Fig. 9) ring-like. Pygofer with ventral margin longer than dorsal margin in lateral view (Fig. 10), mediovental processes distinct (Fig. 9). Aedeagus (Fig. 11) with phallobase distinct. Genital styles (Figs 12, 13) simple, long.

Bamboo.

Oriental Region (China).

This genus is similar to Arcofaciella Fennah, 1956 but differs from it by: frons with median carina distinctly developed, with lateral carinae subparallel (frons with median carina not delveloped, with lateral carinae arched in Arcofaciella); postclypeus with median carina developed (postclypeus with median carina absent in Arcofaciella); spinal formula of hind leg 5-6-4 (spinal formula of hind leg 5-8-5 or 5-9-5 in Arcofaciella); anal segment of male with two processes large and lamellate (anal segment of male with two processes short and spinous in Arcofaciella).

This genus is also similar to Mucillnata Qin & Zhang, 2010 but differs from it by: frons distinctly inclined anteriorly in lateral view (frons not distinctly inclined anteriorly in lateral view in Mucillnata); lateral carinae of the pronotum not diverging and attaining the hind margin (lateral carinae of the pronotum diverging and not attaining the hind margin in Mucillnata); pygofer of male with ventral margin with two processes (pygofer of male with a medioventral process in Mucillnata); anal segment of male with two lateral processes (anal segment of male with single process on the caudoventral margin on right side in Mucillnata).

17♂♂, 20♀♀, China: Yunnan, Yingjiang County (24°44N, 97°33E), on bamboo, 15 August 2015, Xiang-Sheng Chen and Lin Yang; 12♂♂, 18♀♀, Yunnan, Yingjiang County, on bamboo, 18 August 2018, Hong-Xing Li, Qiang Luo and Liang-Jing Yang.

Body length (from apex of vertex to tip of tegmina): male 3.2–3.5 mm (N = 17); female 3.4–3.8 mm (N = 20); tegmen length: male 2.7–3.0 mm (N = 17); female 2.8–3.3 mm (N = 20).

General color yellowish green (Figs 1–4). In dorsal view, a white large longitudinal stripe along median line from basal half of frons to the end of mesonotum (Fig. 5). Rostrum with apex dark brown. Eyes yellowish brown to blackish brown. Ocelli reddish brown. Pronotum with a white longitudinal band along lateral margin (Fig. 5). Tegulae yellowish white. Tegmina with white spots along longitudinal veins in apical half, along transverse vein and apical veins bordered yellowish brown stripes as figured (Fig. 8). Wings hyaline, with veins brown.

Ratio width of vertex at base to length 2.9–3.2, to width at apex 1.3–1.5, lateral margin slightly keeled, Y-shaped carina distinct (Fig. 5). Frons with ratio length to width 1.5–1.8, the widest at near ocelli. Ratio length of rostrum to width 7.4–7.6. Basal segment of antennae with ratio length to width 1.3–1.6, to length of second segment 0.5–0.6 (Fig. 6). Pronotum with ratio length in midline to length of vertex 2.2–2.4, anterior margin straight, posterior margin concave. Mesonotum in midline 3.5–3.8 times longer than pronotum, 2.4–2.7 times longer than vertex and pronotum combined (Fig. 5). Tegmina (Fig. 8) amply exceeding the tip of abdomen, 2.5 times longer than wide, with apical margin broadly rounded; Sc+R and M with common petiole at base, and forked before midline; Sc and R with two branches respectively; M with three branches at apical, M₁ fused with Rs basally, and M₃ fused with Cu₁a basally; Cu with three branches; A with two branches fused at apical half.

Anal segment short, with inverse collar-shaped in posterior view, with lateral processes large and lamellate, apical margin roundly convex (Fig. 9). Pygofer with mediovental processes paired, finger-like, directed each other, opening oval, longer than wide, with ratio length to width 1.5 (Fig. 9), in profile with dorsal margin longer than ventral margin (Fig. 10). Aedeagus (Fig. 11) with phallobase distinct. Phallus tubular, with basal third exceeding the phallobase cephalad, and with apical fifth exceeding phallobase caudad, directed dorsad. Phallobase with apical two thirds narrowing apically, directed ventrad, dorsal margin with a stout tooth-like process at base and ventral margin with another small tooth-like process at basal third, in posterior view ring-like, opening narrow. Genital styles in profile (Fig. 13) with ventral margin distinctly convex, and with dorsal margin slightly concave, in posterior view (Fig. 12) moderately long, flake-shaped, broad at middle, apex acute, reaching the base of anal segment.

Anal style exceeded pygofer. Pygofer with gonocoxa VIII moderately large, basal third with inner lateral margin sinuate. Ovipositor longer than pygofer. Gonangulum small, with width wider than length, basal margin subangular convex in the middle, apical margin slightly convex, separated from gonocoxa VIII. Gonoplacs elongate, sword-like, with apex beyond apical margin of pygofer (Fig. 14). Gonapophyses IX (Fig. 15) slender, gradually narrowed apically, apex sharp, dorsal margin with apical half serrated.

Bamboo (Phyllostachys sp.).

Southwest China (Yunnan Province) (Fig. 16).

Figure 16. 

Geographic distribution of Arcifrons arcifrontalis Ding & Yang, 1986 in China (black triangle).

Figures 17, 18. 

Adult of Arcifrons arcifrontalis Ding & Yang, 1986 resting on leaf of bamboo. Photographed by Xiang-Sheng Chen.