1a |
Wing with brown apical spot . |
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2 |
b |
Wing entirely hyaline to brown, but without apical spot. |
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4 |
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2a |
Eye at least 1.4 times (usually 1.5-1.55) as high as long. Frons wider than long or at most as long as wide, deeply pitted. Larger flies, wing length 4.5-6.5 mm. |
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3 |
b |
Eye round, less than 1.3 (1.2-1.25) as high as long . Frons longer than wide, inconspicuously dotted. Smaller flies, wing length less than 4.5 (usually 2.5-3.5) mm. |
U. salonikiensis Hennig |
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3a |
Halter yellow. |
U. apicalis Meigen |
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b |
Halter black. |
U. megacephala Loew |
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4a |
Side of frons with triangular white microtrichose area. At least wing base (cell bc) brown. |
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5 |
b |
Frons sides shining, at most eye narrowly bordered with whitish microtrichose areas. Wing variable. |
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6 |
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5a |
Mesonotum densely shagreened, almost matt . Wing at anterior margin (including cell c) widely brown . Frons in profile straight or slightly convex, orbital plate and gena moderately or short setose (longest setae shorter than antenna); parafacialium and face black. |
U. atrata Loew |
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b |
Mesonotum shining black or finely shagreened. Wing hyaline, except cell bc, base of cell c and stigma usually brown . Frons in profile usually concave, orbital plate and gena long setose (longest setae longer than antenna); parafacialium and face reddish yellow. |
U. ruficeps Becker |
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6a |
Tarsi entirely black. Face, gena and most of frons dark brown to black. Eye less than 1.3 (1.1-1.2) times as high as long. |
U. omani Steyskal |
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b |
Mid- and hindtarsi at least partly yellowish to reddish. Other characters variable. |
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7 |
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7a |
Anterior part of head (frons above lunule, sometimes face and parafacialium) reddish; eye round (less than 1.3 times as high as long). |
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8 |
b |
Anterior part of head mainly black; eye oval (more than 1.3 times as high as long). |
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9 |
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8a |
Frons satin subshining and smooth in the middle, dotted laterally ; pterostigma and veins brownish; mesonotum densely shagreened, almost matt. Male hindfemur unmodified, as wide as midfemur. |
U. facialis Hendel |
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b |
Frons shining and pitted over whole anterior half ; pterostigma and veins hyaline, if veins darkened, then wing uniformly brownish and mesonotum shining. Male hindfemur swollen in distal part . |
U. wadicola Steyskal |
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9a |
Wing brownish grey except basal one-quarter (fig.). Apical portion of distiphallus ("glans") with a few blunt sclerotized projections, but without claw-like or rasper-like structures (fig. ). |
U. nigripennis Loew |
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b |
Wing uniformly yellowish or hyaline (figs ). Apical portion of distiphallus ("glans") either with sharply pointed, claw-like projections or rasper-like structures (fig. ) |
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10 |
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10a |
Abdominal tergites subshining, shagreened.
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U. semiopaca Loew |
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b |
Abdominal tergites smooth, shining.
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11 |
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11a |
Wing with yellowish tinge (figs ). Apical portion of distiphallus with blunt sclerotized projections and rasper-like structures (fig. ). |
U. erythrophthalma Meigen |
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b |
Wing hyaline, without yellowish tinge (figs ). Apical portion of distiphallus with sharply pointed, claw-like projections and less distinguishable rasper-like structures (fig. ). |
U. albidipennis Loew |
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