| 1 |
Stripe of pale tomentum on the pleurae reduced to the dorsal part of the mesopleuron (Fig. 1). . . . . . . . . . . . . . . . . . 2 |
| - |
Stripe of pale tomentum on the pleurae not as in Fig. 1. . . . . . . . . . . . . . . . . . 3 |
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| 2 |
Size: 8-10 mm. Thorax with reddish humeral callus and notopleuron . . . . . . . . . . . . . . . . . . rufithrorax Loew, 1853 |
| - |
Size: 12-14 mm. Thorax sometimes with brownish humeral callus and notopleuron . . . . . . . . . . . . . . . . . . cothurnata Meigen, 1820 |
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| 3 |
Stripe of pale tomentum on the pleurae dorsally interrupted (Fig. 2, 3). . . . . . . . . . . . . . . . . . 4 |
| - |
Stripe of pale tomentum on the pleurae not as in Fig. 2, 3. . . . . . . . . . . . . . . . . . 5 |
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| 4 |
Coxae yellowish. Stripe of pale tomentum on the pleurae like in Fig. 2. . . . . . . . . . . . . . . . . . lateralis Meigen, 1804 |
| - |
Coxae blackish. Stripe of pale tomentum on the pleurae like in Fig. 3. . . . . . . . . . . . . . . . . . longicornis Meigen, 1820 |
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| 5 |
Stripe of pale tomentum on the pleurae complete, also a ventral stripe above the middle coxa (Fig. 4). . . . . . . . . . . . . . . . . . hyalipennis (Fabricius, 1794) |
| - |
Stripe of pale tomentum on the pleurae complete, but a ventral stripe above the middle coxa is missing (Fig. 5). . . . . . . . . . . . . . . . . . 6 |
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| 6 |
Face with a silky and blackish tomentum, only the eyemargins have a paler tomentum. Tergite 3 and 4 reddish. Mystax black (according to Becker). [Only females are known]. . . . . . . . . . . . . . . . . . meyeri Nowicki, 1867 |
| - |
Face with a normal tomentum (except in oelandica, which has a black stripe in the middle of the face). . . . . . . . . . . . . . . . . . 7 |
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| 7 |
Abdomen with reddish or yellowish spots or stripes on the middle tergites, sometimes they are missing. All coxae yellowish (if the front and middle coxae are blackish, compare the description of flavipennis Meigen, 1820). . . . . . . . . . . . . . . . . . 8 |
| - |
Abdomen black, or only some tergites have paler hind margins, or only the last tergites are reddish (which can be found sometimes in harcyniae Loew, 1844]. Coxae yellowish or blackish. . . . . . . . . . . . . . . . . . 12 |
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| 8 |
Thorax with reddish humeral callus and notopleuron. . . . . . . . . . . . . . . . . . 9 |
| - |
Thorax black. . . . . . . . . . . . . . . . . . 10 |
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| 9 |
1st antennal segment 2 times as long as segment 2. Mystax yellowish in both sexes. . . . . . . . . . . . . . . . . . humeralis Zeller, 1840 |
| - |
1st antennal segment 1.25 times as long as segment 2. Mystax balck in males. . . . . . . . . . . . . . . . . . engeli Noskiewicz, 1953 |
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| 10 |
Mesonotum with distinct tomented stripes. 1st antennal segment longer than the 2nd. . . . . . . . . . . . . . . . . . linearis (Fabricius, 1787) |
| - |
Mesonotum without distinct tomented stripes (predominantly shiny). 1st antennal segment not longer than the 2nd. . . . . . . . . . . . . . . . . . 11 |
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| 11 |
Hind metatarsus strongly widened. Front - and middle tibia, also hind femora yellowish in males [?]. Females can not been seperated from gracilis. . . . . . . . . . . . . . . . . . bicincta Meigen, 1820 |
| - |
Hind metatarsus weaker widened. Front - and middle tibia apically blackish; hind femora dorsally with black stripe [?]. Females can not been seperated from bicincta. . . . . . . . . . . . . . . . . . gracilis Meigen, 1820 |
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| 12 |
Legs blackish, knees sometimes paler . . . . . . . . . . . . . . . . . . 13 |
| - |
Legs partly or completely yellowish. . . . . . . . . . . . . . . . . . 14 |
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| 13 |
Frons on the eyemargin with curved, black, and long hairs. Frontal tubercle lower than the length of the 2nd antennal segment. Wing a little bit brownish in both sexes. . . . . . . . . . . . . . . . . . harcyniae Loew, 1844 |
| - |
Frons on the eyemargin only with short and yellowish hairs. Frontal tubercle nearly as high as the length of the 2nd antennal segment. Wing of the male blackish at the base, apically transparaent; wing of the female a little bit brownish. . . . . . . . . . . . . . . . . . atricapilla Meigen, 1804 |
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| 14 |
Yellowish or whithish tomentum of the face with a vertical black stripe. Wing clearly darkened, especially in the male. Greater animals (15-20 mm). . . . . . . . . . . . . . . . . . oelandica (Linnaeus, 1758) |
| - |
Tomentum of the face without a vertical black stripe. Wing not so darkened. Smaller animals (5-14 mm). . . . . . . . . . . . . . . . . . 15 |
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| 15 |
Style of the 3rd antennal segment as long or something longer than the 2nd segment. . . . . . . . . . . . . . . . . . 16 |
| - |
Style of the 3rd antennal segment shorter than the 2nd segment. . . . . . . . . . . . . . . . . . 17 |
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| 16 |
Frontal tubercle as high as the length of the 2nd antennal segment. Mystax yellowish. 1st antennal segment 2.25 times as long as segment 2. . . . . . . . . . . . . . . . . . flavipennis Meigen, 1820 |
| - |
Frontal tubercle low. Mystax composed by hairs, which are blackish at their bases and yellowish at their tips. 1st antennal segment 1.5 times as long as segment 2. . . . . . . . . . . . . . . . . . lata Loew, 1853 |
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| 17 |
Coxae yellowish, Body length: 5-6 mm. . . . . . . . . . . . . . . . . . puerilis Becker, 1923 |
| - |
Coxae blackish. Body length greater. . . . . . . . . . . . . . . . . . 18 |
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| 18 |
Top of the back of the head and palpi with yellowish or brownish hair. . . . . . . . . . . . . . . . . . rufipes (De Geer, 1776) |
| - |
Top of the back of the head and palpi with black hair. . . . . . . . . . . . . . . . . . sudetica Duda, 1940 |
