Acidiostigma bimaculatum Wang, 1996

Chen, Xiaolin, Zhang, Lijie & Zhao, Mingshui, 2016, Three new species of Acidiostigma Hendel (Diptera: Tephritidae: Trypetinae) and an updated key to species from the eastern Palaearctic and Oriental Regions, Zootaxa 4092 (3), pp. 401-413 : 403-406

Acidiostigma bimaculatum Wang, 1996 .

( Figs 1–14 )

Acidiostigma bimaculata Wang, 1996:137 .

Diagnosis. Closely resembling A. lucens (Munro) from India, but differs by cell br entirely brown; cell r4+5 with 2 smaller hyaline spots; cell sc subequal to cell c and the basal half of cell dm brown.

Male (described for the first time). Head ( Fig 2 ). Predominantly yellow to yellow-brown, face usually darker; 3 pairs of frontal and 2 pairs of orbital setae; ocellars moderately developed, slightly longer than posterior orbitals. The 1st flagellomere rounded at apex; arista pubescent. Thorax ( Figs 1, 4 ). Reddish yellow in ground colour, with 4 broad longitudinal black vittae on scutum, a narrow ivory-yellow stripe extending from postpronotal lobe along upper margin of anepisternum to wing base; mediotergite completely shiny black. Body setae black, dorsocentral setae situated behind line of postsutural supra-alars. Legs ( Fig 1 ). Entirely yellow, fore femora each with 4–6 posteroventral setae; mid tibia with 1 strong apical spur. Wings ( Figs 1, 3 ). The pattern is typical Hemilea -like, with anterior 1/2 brown and posterior portion hyaline; cells bc and c almost entirely brown; cell r1 with 2 prominent hyaline spots; cell sc entirely brown, subequal in length to cell c; lobe of cell bcu short; vein R4+5 setose to crossvein R-M, the latter situated well beyond the middle of cell dm. Abdomen ( Fig 5 ). Almost entirely black except for tergite 1 yellow-brown and a small medial yellow-brown spot on posterior margin of tergite 5.

Length. Body, 6.2–7.1 mm; wing, 7.0– 8.2 mm.

Female (supplement to the species description of Wang, 1996). Oviscape shiny and brownish black, flattened, much longer than tergite 6 and slightly longer than tergite 5, without any outstanding marginal setae ( Fig 6 ). Eversible membrane with taeniae about half as long as membrane, medially with strong triangular teeth, posteriorly with smaller triangular teeth ( Fig 7 ). Aculeus broad and apically tapered to a point and serrated on sides ( Fig 8 ).

Distribution. China (Sichuan, Zhejiang).

Specimens examined. Holotype female, CHINA: Sichuan: Mt. Emei (29. 5 N, 103. 3 E), 13 September 1943. Other material: 8♂, CHINA: Zhejiang, Tianmushan, Xianrending, 1500m, 10–28 June 2014, Y. Wang; 1♂, CHINA: Zhejiang, Tianmushan, Xianrending, 1500m, 28 August 2014, Y. Wang; 11♀, CHINA: Zhejiang, Tianmushan, Xianrending, 1500m, 26–28 August 2014, Y. Wang; 11♀, CHINA: Zhejiang, Tianmushan, Xianrending, 1500m, 9 July 2014, Y. Wang; 10♀, CHINA: Zhejiang, Tianmushan, Xianrending, 1500m, 10–28 June 2014, Y. Wang. All materials deposited in IZCAS.

Biology. Adults appear from late May to early September in Tianmu Mountain, Zhejiang Province. They usually rest on the upper or undersides of leaves of Euonymus hamiltonianus Wall (Celastraceae) , which is distributed mainly in south China and India, and is one kind of common plants in Tianmu Mountain. The average temperature in their resting site usually is 19–22°C, and average humidity about 62–67%. Adults were observed to rest on E. hamiltonianus , sometimes with more than 30 individuals in one tree, in the summers of 2014 and 2015. They were also often found to feed on leaf liquids ( Fig 11 ), flower honey ( Fig 12 ) or decaying protein on E. hamiltonianus . Males frequently fought with each other when meeting on the same leaf ( Fig 13 ). And the courtship interactions between males and females have been observed. Females were also found using their aculeus to pierce leaves of E. hamiltonianus ( Fig 14 ) at high frequency (the motion is very like laying eggs); this behavior has been observed to last several seconds to one minute each time in the summer of 2015.

Remarks. The specimens collected from Zhejiang have slight wing variation (smaller hyaline mark in cell r4+5) with that collected from Sichuan; however, no other distinct different found. In Tephritidae , trivial wing variations are often present in the same species. If no other variations appear, the specimens with slight wing variations are usually taken as the same species.

The male of this species is slightly differentiated from the female by mediotergite completely shiny black and abdomen almost entirely black except for a small medial yellow mark on posterior margin of tergite 5. The conspecific of males and females has been confirmed by definite courtship interactions observed in Tianmu Mountain in 2015.

Figures

FIGURES 1 – 10 Acidiostigma bimaculatum 1. Habitus (male), lateral view; 2. Head (male), anterior view; 3. Wing (male); 4. Scutum (male), dorsal view; 5. Abdomen (male), dorsal view; 6. Aculeus (female), dorsal view; 7. Eversible membrane, dorsal view; 8. Tip of aculeus, dorsal view; 9. Epandrial complex, posterior view; 10. Epandrial complex, lateral view

FIGURES 11 – 14 Acidiostigma bimaculatum 11. Habitus, feeding on leaf of Euonymus hamiltonianus; 12. Habitus, feeding on flower of E. hamiltonianus; 13. Habitus (2 males), fighting with each other on the leaves of E. hamiltonianus; 14. Habitus (female, suspected to be laying eggs)