Centorisoma sexangulatum, Liu, Xiaoyan & Yang, Ding, 2014

Liu, Xiaoyan & Yang, Ding, 2014, Five new species of Centorisoma Becker from China, with an updated key to world species (Diptera, Chloropidae), Zootaxa 3821 (1), pp. 101-115 : 112-114

Centorisoma sexangulatum sp. n.

Figs 5 , 31–37

Diagnosis. Body yellow. Postpedicel 1.3 times as long as its basal breadth. Scutum with 5 yellowish orange longitudinal stripes, basal 2/3 of inner lateral stripes brown. Cercus rather large, distinctly reduced at ventral 1/3. Postgonite distinctly produced beyond basiphallus and without minute serrations on inner margin near basiphallus.

Description. Male. Body length 2.5–2.9 mm, wing length 1.7–2.3 mm.

Head yellow without microtomentum, 0.8 times as long as high, as wide as thorax; face somewhat concave in lateral view, facial carina indistinct; frons 0.9 times as long as wide, projecting only slightly in front of eye; gena broad, 0.5 times as wide as postpedicel; parafacial narrow. Ocellar triangle smooth, shiny yellow, marginally and apically brown, with a diamond-shaped brown spot on median area in front of ocelli, reaching to anterior margin of frons, with pointed apex; ocellar tubercle light brown. Occiput brown. Cephalic setae and setulae black; oc and poc hair-like, oc as long as poc; vte and vti developed, vte as long as vti. Antenna yellowish brown with thick grayish microtomentum except basoventral portion of postpedicel yellow, dorsodistal margin of postpedicel black; postpedicel 1.3 times as long as its basal breadth, basal 1/2 weakly concave on dorsal margin; arista white except basal segment pale yellow, with short white yellow setulae. Proboscis and palpus yellow with yellow setulae.

Thorax yellow with microtomentum, evenly covered with short setulae. Postpronotum with a small yellowish orange spot. Scutum 1.2 times as long as wide, with 5 yellowish orange longitudinal stripes, medial stripe slightly broad and extending to posterior 3/5 of scutum, basal 2/3 of inner lateral stripes narrow, brown, outer lateral stripes short and narrow. Thoracic pleuron shiny without microtomentum except for paratergite and ventral portion of anepimeron brown, anteroventral margin of anepisternum, dorsal portion of anepimeron, ventral 2/3 of katepisternum and ventral 1/2 of katepimeron yellowish orange. Postnotum brown. Scutellum yellow, 0.6 times as long as wide; ap sc short, slightly shorter than scutellum. Setae and setulae on thorax black; npl 1+2, a npl hairlike, p npl developed, a npl as long as p npl; a pa developed and p pa hair-like, a pa 1.6 times as long as p pa; 1 dc developed, as long as a pa. Legs yellow except for fore tibia and tarsus brown, basal portion of fore tibia yellow. Setulae on legs brown. Mid tibia with a distinct black subapical spur nearly as long as diameter of tibia. Tibial organ oblong, narrow. Wing 2.9 times as long as wide, hyaline; veins brown. Relative lengths of 2nd: 3rd: 4th costal sections = 3: 2: 1; crossveins r-m and m-m not approximate, r-m at basal 0.6 of discal cell. Halter pale yellow.

Abdomen shiny yellow except for tergites 1–5 brownish on middle portion; venter yellow. Setulae on abdomen brown.

Male genitalia ( Figs. 31–34 ): Epandrium yellow with many setulae; surstylus horizontally articulated with epandrium, strongly narrowed at apex, elongate. Cercus rather large, 1.5 times as long as wide, distinctly reduced at ventral 1/3, apical margin round, articulated with distinct inner surstylar plate. Gonites arranged in a row, with a distinct demarcation at middle; postgonite gradually narrowed distally, far produced beyond basiphallus and without minute serrations on inner margin near basiphallus; basiphallus short; phallapodeme long, extended to base of basiphallus, with basal stalk broad in lateral view. Hypandrium broad.

Female. Body length 3.0– 3.2 mm, wing length 2.2–2.3 mm.

Female genitalia ( Figs. 35–37 ): Tergite 9 trilateral, basal margin round, with 2 long setae; sternite 9 long, apically round with long stout setae. Cercus short and stout with some long setae.

Type material. Holotype ♂, CHINA: Ningxia: Liupan Mountain, Qiuqianjia, 7. VII. 2008, Jingxian Liu. Paratypes 1 ♂, Liupan Mountain, Guamashan, 9. VI. 2008, Jingxian Liu; 1 ♂, Beijing: Shidu, 1–2. VIII. 2009, Jinjing Wang; 1 ♂, Yanqing, Songshan, 15. VIII. 2003, Hui Dong; 3 ♂, 2 ♀, Hebei: Xiaowutai, Xilingshan, 26. VI. 2009, Shan Huo; 2 ♂, Xiaowutai, Shanjiankougou, 24. VI. 2009, Junchao Wang; 2 ♂, 3 ♀, Xiaowutai, Yangjiaping, 29. VI. 2009, Junchao Wang.

Distribution. China: Ningxia, Beijing, Hebei.

Remarks. The new species is somewhat similar to C. flavum Nartshuk in the ocellar triangle yellow, marginally and apically brown, with a diamond-shaped brown spot and the legs yellow except for fore tibia and tarsus brown. It can be separated from the latter by the following features: postpedicel 1.3 times as long as its basal breadth; longitudinal stripes on scutum yellowish orange except basal 2/3 of inner lateral stripes brown; cercus rather large, 1.5 times as long as wide. In C. flavum , the postpedicel is 1.8 times as long as its basal breadth; the longitudinal stripes on the scutum are reddish brown; the cercus is very small ( Nartshuk 1965, 2005).

Etymology. The specific name is from the Latin sexangulatus (“hexagonal”), refers to the shape of the cercus.

Figures

FIGURE 5. Centorisoma sexangulatum sp. n., male. body, lateral view. Scale bar = 0.5 mm.

FIGURES 31 – 34. Centorisoma sexangulatum sp. n., male. 31 epandrium, posterior view; 32 epandrium, lateral view; 33 hypandrium and phallic complex, ventral view; 34 hypandrium and phallic complex, lateral view. Scale bar = 0.1 mm.

FIGURES 35 – 37. Centorisoma sexangulatum sp. n., female. 35 abdominal terminalia, dorsal view; 36 abdominal terminalia, lateral view; 37 abdominal terminalia, ventral view. Scale bar = 0.1 mm.