Megaselia bisticta, Wang, Jian-Feng & Liu, Guang-Chun, 2016

Wang, Jian-Feng & Liu, Guang-Chun, 2016, A new species of Megaselia Rondani (Diptera, Phoridae) with wing-spots from China, Zootaxa 4067 (5), pp. 581-584 : 582-584

Megaselia bisticta , sp. nov. ( Figures 1–10 )

Etymology. The specific name is from the Latin for “two spotted” and refers to the two brownish pigmented spots on each wing.

Diagnosis. The new species is similar to M. conglomerata in terms of two wing-spots. It can be distinguished from the latter in: (1) Costa long (costal index about 0.61), and the latter Costa shorter (costal index about 0.43–0.44). (2) wing with a big, diamond, brownish pigmented spot between the apex of vein R4+5 and the middle of vein M1, and the spot is inclined 45 degrees with costa; and a small wedge-shape brown pigmented spot between the middle of veins M1 and M2. And in the latter, wing with an oblong brownish spot on anterior margin above apex of M1 vein, and a rounded brown patch between apex of M1 and M2 veins.

Description. Male. Body length 1.9–2.0 mm ( Figure 1 ).

Head ( Figure 2 ). Frons black, width about 0.3 mm, broader than height (2.0:1), with about 50 hairs and a distinct median furrow. Lower supra-antennal bristles short, about 2/3 as long as upper pair. Pre-ocellars slightly further from each other than upper supra-antennals. Antials closer to antero-laterals than to upper supra-antennal bristles and slightly lower than antero-laterals. Pre-ocellars nearly parallel on frons to medio-laterals and with equal distance each other. Postpedicels black or dark brown and without SPS vesicles. Arista obviously longer than frons width. Palps yellow with strong bristles which are obviously longer than maximum width of palps.

Thorax. Thoracic dorsum black and flank dark brown. Mesopleuron with a few fine hairs. Notopleuron with 3 bristles and no cleft. Scutellum with a pair of bristles. Legs ( Figures 3–5 ) brown, but fore legs paler. Hind femur darkened at tip. Fore metatarsus longer than joints 2+3. Dorsal hair palisade of mid tibia extends 0.6 of its length. Hairs short below basal half of hind femur and anteroventral row of outer half, but the latter is longer than the former. Hind tibia with strong posterodorsal hairs and without anterodorsal hairs. Wings ( Figure 6 ) nearly hyaline, with yellowish brown veins. A big diamond brownish pigmented spot is between the apex of vein R4+5 and the middle of vein M1, and the spot is inclined 45 degrees with costa; and a small wedge-shape brown pigmented spot is between the middle of veins M1 and M2. The area between the spots and the anterior margin of the wings is pale brown. Costal index about 0.61. Costal ratio 2.6:2.6:1. Costal cilia about 0.07mm. Vein Sc runs to R1. Base of vein Rs with 1 minute hair, which is slightly shorter than vein R2+3. Vein M1 obviously bent near the center. Axillary ridge with 3 bristles. Halteres black.

Abdomen ( Figures 7–10 ). Abdominal tergites dark brown, but venter paler. Tergites with sparse hairs, which a little longer only at rear of tergite 6. Tergites 2–6 subequal in length. Venter with fine hairs below on segments 3–6. Hypopygium dark brown, with yellow anal tube. Each side of epandrium with a single long bristle and some small bristle-like hairs. Anal tube subequal to the length of dorsal edge of epandrium. Hairs at tip of anal tube and the longest hairs of cerci subequal.

Female: unknown.

Type materials. Holotype: ♂, China: Guangxi, Shiwandashan Mountain (21°52′N, 107°55E, 1260m), 7-VIII-2015, Li Chun-feng collected by sweep nets. Paratypes: 1♂, same data as holotype; 3♂♂, China: Guangxi, Shiwandashan Mountain (21°52′N, 107°55E, 1260m), 7-VIII-2015, Gao Bo-ling collected by sweep nets.

Distribution. China (Guangxi)

Discussion. Megaselia species with wing-spots are rare, and only six spotted-wing species have been described. Most wing-spots are composed of pigmented wing membrane, except M. dickoni and M. conglomerata . M. dickoni have a distinctive big wing spot was composed of pigmented scales, diameter about 0.22m, and intercepted by M1 and M2 veins. The darkening of the wing in M. conglomerata was caused by approximation of the microtrichia ( Malloch 1912), but Borgmeier (1964) consided that the wing-spots of M. conglomerata were caused by the pigmentation of the membrane as was clearly evident when the wing was examined under great magnification. And we think that Borgmeier’s views are more likely to be the truth by examined holotype photos of M. conglomerata .

Acknowledgement. We are grateful to Emily A. Hartop, Natural History Museum of Los Angeles County, for her critical comments of early manuscript and supplying kindly her photos of type specimens. We also thank to Dr. Henry Disney, Cambridge University for his critical comments of early manuscript. The project was supported by the National Natural Science Foundation of China (31201743, 31372245) and the Liaoning Province Education Administration (l2013452).

Figures

FIGURE 1. Megaselia bisticta sp. nov. body in left lateral view. Scale bar = 0.5 mm.

FIGURES 2 – 10. Megaselia bisticta sp. nov. 2: head; 3: fore leg; 4: mid leg; 5: hind leg; 6: wing; 7, 9: hypopygium in left lateral view; 8, 10: hypopygium in right lateral view. 3 – 6: Scale bars = 0.2 mm; 2, 7 – 10: Scale bars = 0.05 mm.