Centorisoma mediconvexum, 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 : 105-106

Centorisoma mediconvexum sp. n.

Figs 2 , 13–19

Diagnosis. Gena 0.5 times as wide as postpedicel. Postpedicel 1.4 times as long as its basal breadth. Cercus rather large with a small convexity on dorsal margin. Postgonite produced beyond basiphallus, without minute serrations on inner margin near basiphallus.

Description. Male. Body length 3.3 mm, wing length 2.6 mm.

Head brown without microtomentum, 0.9 times as long as high, as wide as thorax; face yellow with a triangular brown spot on middle portion, somewhat concave in lateral view, facial carina indistinct; frons yellowish brown except distal 1/3 yellow, as long as wide, projecting only slightly in front of eye; gena anteriorly yellow with lower margin brown, broad, 0.5 times as wide as postpedicel; parafacial narrow. Ocellar triangle brown, smooth, shiny, reaching to anterior 0.9 of frons, with pointed apex; ocellar tubercle light brown. Cephalic setae and setulae black; oc and poc hair-like, oc as long as poc; vte and vti developed, vte slightly longer than vti. Antenna yellowish brown with thick grayish microtomentum except dorsodistal portion of postpedicel black, ventral 1/3 of postpedicel yellow; postpedicel 1.4 times as long as its basal breadth, basal 1/3 weakly concave on dorsal margin; arista white except basal segment pale yellow, with short pale yellow setulae. Proboscis yellow with yellow setulae; palpus brown with brown setulae.

Thorax black with microtomentum, evenly covered with short setulae. Scutum with granulated microsculpture, 1.2 times as long as wide. Thoracic pleuron shiny brown without microtomentum except for anteroventral portion of anepisternum, ventral 2/3 of katepisternum and ventral 1/2 of katepimeron black. Scutellum 0.6 times as long as wide; ap sc short, distinctly shorter than scutellum. Setae and setulae on thorax black; npl 1+2, a npl hair-like, p npl developed, a npl as long as p npl; a pa developed and p pa hair-like, a pa 1.5 times as long as p pa; 1 dc hair-like, as long as a pa. Legs yellow except all femora and hind tibia yellowish brown; fore tarsus, mid and hind tarsomere 5 brown. Setulae on legs brown. Mid tibia with a distinct black subapical spur. Tibial organ oblong, narrow. Wing 2.8 times as long as wide, hyaline; veins brown. Relative lengths of 2nd: 3rd: 4th costal sections = 2.5: 1.7: 1; crossveins r-m and m-m not approximate, r-m at basal 0.6 of discal cell. Halter pale yellow.

Abdomen shiny brown except for basal portion of tergite 1 yellow; venter yellow. Setulae on abdomen black.

Male genitalia ( Figs. 13–16 ): Epandrium brown with many setulae; surstylus horizontally articulated with epandrium, strongly narrowed at apex, elongate. Cercus rather large with a small convexity on dorsal margin, ventral 1/3 slightly reduced, 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, 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 4.8 mm, wing length 3.1 mm.

Female genitalia ( Figs. 17–19 ): Tergite 9 triangular, slightly wider than long, 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: Shaanxi: Zhouzhi, Houzhenzi, 19. VII 2010, Tingting Zhang. Paratypes 1 ♂, 1 ♀, Hubei: Shennongjia, Yaolangou, 13. VII. 2009, Qifei Liu; 1 ♂, 1 ♀, Sichuan: Emei Mountain, Linggongli, 5. VII. 2010, Tao Li.

Distribution. China: Shaanxi, Hubei, Sichuan.

Remarks. The new species is somewhat similar to C. ussuriense Nartshuk in the following aspects: gena 0.5 times as wide as postpedicel and postpedicel 1.4 times as long as its basal breadth. It can be separated from the latter by the following features: postpedicel yellowish brown except dorsodistal portion black, ventral 1/3 yellow; cercus large with a small convexity on dorsal margin, ventral 1/3 slightly reduced; postgonite without minute serrations on inner margin near basiphallus. In C. ussuriense , the postpedicel is yellow, blackened on dorsodistal portion; the cercus is rather broad, slightly emarginate apically; the postgonite bears minute serrations on inner margin near basiphallus ( Nartshuk 1965; Kanmiya 1983).

Etymology. The specific name is from the Latin medi- (“middle”) and convexus (“convex”), refers to the small convexity on dorsal margin of the cercus.

Figures

FIGURE 2. Centorisoma mediconvexum sp. n., male. body, lateral view. Scale bar = 0.5 mm.

FIGURES 13 – 16. Centorisoma mediconvexum sp. n., male. 13 epandrium, posterior view; 14 epandrium, lateral view; 15 hypandrium and phallic complex, ventral view; 16 hypandrium and phallic complex, lateral view. Scale bar = 0.1 mm.

FIGURES 17 – 19. Centorisoma mediconvexum sp. n. female. 17 abdominal terminalia, dorsal view; 18 abdominal terminalia, lateral view; 19 abdominal terminalia, ventral view. Scale bar = 0.1 mm.