Megaselia nigrifinis Liu & Chen 2019, sp. nov.

Megaselia nigrifinis sp. nov.

(Figs. 1–9)

Diagnosis. Mesopleuron bare, notopleuron with two bristles; notopleural cleft weakely developed and without sclerotised ridges; scutellum with a posterior pair of bristles and an anterior pair of hairs (male) or two pairs of bristles (female); hypopygium brown, left side of epandrium with 12–14 uniformly robust hairs; wing costal index 0.46–0.47; male abdominal tergites yellow, with brownish patches on each side of tergites II–V; female abdominal tergites uniformly pale yellow, tergite VI longer than wide. Dufour’s crop mechanism oval, with two arms.

Description. Male (Fig. 1). Frons brown, a little broader than long, with 60–70 hairs, dulled by dense microtrichia. Antial bristle closer to eye margin than to median furrow. Lower Supra-antennal bristles robust, but distinctly shorter and less robust than upper pair. Postpedicel subglobose, brown, diameter a little less than half frontal width. Subcuticular pit sensilla (SPS) densely distributed around postpedicel, from base to about level of insertion point of arista. Diameter small to medium (0.008–0.009 mm). Arista brown. Pubescence of third aristomere about as long as diameter of basal segment. Sensilla at base of third aristomere usually well separated. Palps yellow, with 6–7 bristles and some hairs. Proboscis with pale yellowish labrum and labella. Prementum with two pairs of hairs. Width of labrum about two third of pedicel. Labella with 5 pseudotracheae, 20–22 spinules and some longer hairs on lower face. Thorax yellow, to yellowish brown on top. Mesopleuron bare, notopleuron with two bristles and a notopleural cleft (Fig. 9), and a short humeral bristle. Rest of scutum with a post-alar and a prescutellar dorsocentral bristle each side. Scutellum with a posterior pair of bristles and an anterior pair of hairs, which are about 1/4 as long as posterior pair. Abdominal tergites (Fig. 3) yellow, with brownish patches on each side of tergites II–V. Tergites with sparse hairs except for a few longer ones at rear margins of tergites V–VI. Venter pale yellow. Hypopygium (Fig. 4) brown and anal tube pale yellow. left side of epandrium with 12–14 robust hairs. Hairing of epandrium relatively uniform, gradually becoming a little stronger towards lower margin. Left side of hypandrium with a long postero-ventral lobe. Cerci with 6–8 hairs, which are shorter than terminal bristles of proctiger. Legs yellow, with a browish patch at tip of hind femur. Fore tarsus slender, with postero-dorsal hair palisade on all five segments. Ratios of lengths of front tarsal segments ca. 3.37: 1.28:1.15:1:1. Near-dorsal palisade of mid tibia extends four-fifths of length, and with 6–7 differentiated postero-dorsal hairs behind this palisade. The row of 10–12 hairs below basal half of hind femur include some that are a little, but distinctly longer than longest hairs of antero-ventrall row of outer half. Hind tibia with 9-10 differentiated, almost spine-like, postero-dorsal hairs. Spines of apical comb of posterior face all simple. Wing (Fig. 2) length 1.516–1.55 mm. Costal index 0.46–0.47. Costal ratios 3.01–3.28: 1.90–2.02: 1. Longest costal cilia 0.105–0.110 mm. Sc fully developed and reaching R 1. Hair at base of Rs weak (0.034-0.036 mm). Axillary ridge with two hairs, the longer one being equal length as costal cilia. Veins pale brown, with costa being more yellowish brown and vein A 1 +CuA 2 pale greyish brown and obscure at base. Vein M 1 originates beyond fork of Rs. Membrane lightly, but distinctly tinged yellowish brown. Haltere with yellow stem and pale yellow knob.

Female (Fig. 5). Similar to male but differs at follows: Frons with 70–80 hairs. Labrum stronger than in male, about as broad as postpedicel. Scutellum with 2 pairs of bristles, the anterior pair 1/2 as long as the posterior pair. All abdominal tergites uniformly pale yellow. Tergite VI shorter than its width, tergiteVII triangular (Fig. 8). Dufour’s crop mechanism oval, with two arms (Fig. 7). Rectum with 4 rectal papillae. Wing (Fig. 6) length 1.85– 2.03 mm. Costal index 0.45–0.46. Costal ratios 3.50–3.71: 2.09–2.37:1. Costal cilia 0.105–0.110 mm.

Etymology: The species name refers to the black color in tips of hind femur of male and female.

Material examined. Holotype. ♂, China, Jiangsu, Nanjing, The Arboretum of Nanjing Forestry University (30°05′1.6″N, 118°48′51.77″E; 525 m), 19–Apr–2018, Yue-Qin Wang; Paratype. 12 ♂, 14 ♀, same data as holotype.

Remarks. In the keys of Borgmeier (1967), this species will run to couplet 57 of group VII on page 89, to M. claudia Borgmeier, 1967 from Australia. The new species is different from the latter in antial bristle being lower than upper supra-antennals on frons; the abdominal tergites II–V yellow with brown patches on both sides; female with 4 scutellar bristles; and also the detail of hypopygium. The female will run to couplet 29 of group VI on page 85, to M. curticilliata Borgmeier, 1967, which was only known in female. The new species differ from the latter in yellow abdominal tergites, longer costal cilia and 2 hairs on axillary margin. In the key of Disney (1989) the species will run to 212 on page 32, to M. largifrontalis Schmitz, 1939. However, the new species has no bristle between the two strong bristles on notopleuron; male abdominal tergites yellow, with brown patches on each side of tergites II–V; female abdominal tergite VI is not paler than tergiteV(see Disney 2010); hind femur yellow with dark brown tip. In the key of Buck & Disney (2001), the species will run to couplet 4 on page 79, to M. hexanophila Buck, but the latter SPS larger (0.012–0.031 mm) and anal tube long. If scutum color is omitted, the new species will run out at couplet 7 to the undescripted species. In Disney’s key to the males of European species of Megaselia with a notopleural cleft (Disney 2013), the new species runs to 1 on page 67, to M. hexanophila Buck. The differences are described as above.