Sciapus ZELLER 1842

Key to East Palaearctic species of the genus Sciapus (males)

1. Tarsi with one or more segments enlarged (often slightly) …............................................. 2

– All tarsi simple, at most some segments with erect setulae, or elongated, or sometimes 5th segment flattened dorsoventrally and slightly broadened …............................................. 5

2. Mid tarsus with 3rd segment not enlarged, and 4th segment slightly enlarged; fore tarsus simple; body length 5.5–5.8 mm (Primorye) ….................................................................................................................................. S. dytei Negrobov, Maslova et Selivanova, 2012

– Mid tarsus simple; fore tarsus with 4th segment bearing dorsal lobe …............................... 3

3. Acrostichals present; wing vein dm-m straight; body length 7.9–8.1 mm (Primorye, Sakhalin) …............................................................. S. paradoxus Negrobov et Shamshev, 1986

– Acrostichals absent; wing vein dm-m strongly convex ….................................................... 4

4. Epandrial lobe much longer than epandrium, bearing long hairs; antennal pedicel with pale bristles; hind basitarsus much longer than next segment; body length 5.0–8.0 mm (TransPalaearctic) …....................................................................... S. nervosus (Lehmann, 1822)

– Epandrial lobe shorter than epandrium, sparsely ciliated; antennal pedicel with dark bristles; body length 6.0 mm (Amurian Region, Primorye) …...................... S. roderi Parent, 1929

5. Frons, mesonotum and abdomen entirely shining green, only very feebly dusted; cerci mostly fused, each cercus with long free distal projection; organ X (ventral cercal projection) reduced ….......................................................................................................................... 6

– Frons, thorax and abdomen not shining, densely pollinose, sometimes with shining spots or stripes; cerci fused, organ X large …................................................................................. 7

6. Distoventral projection of cercus with short simple setae; surstylus with simple setae at apex; body length 4.7–4.9 mm (Primorye) …............................................................................................................................................ S. incognitus Negrobov et Shamshev, 1986

– Distoventral projection of cercus with ventral fringe of strong flattened bristles and 1 long undulate flattened apical seta; ventral process of surstylus with 2 long undulate flattened apical setae; body length 5.0 mm (Kunashir) ….................................. S. basarukini sp. n.

7. Abdomen entirely dark, rarely with yellow-brown spots laterally at base; body length 4.8 mm (Buryatia, Chita, Irkutsk, Primorye) …...... S. sibiricus Negrobov et Shamshev, 1986

– Abdominal segments 1-4 at least partly yellow.................................................................... 8

8. Lobes of organ X bifurcate, with short apical setae; body length 5.0 mm (Gansu, Inner Mongolia) …..................................................................................... S. flexicornis Parent, 1944

– Lobes of organ X fused to apex, thin and beaked at apex, with curved dorsally distal process; with uninterrupted row of ventral setae decreasing in length towards apex; fore and mid tarsi covered with erect setulae; body length 3.6 mm (Yakutia) …............................................................................................................. S. vladimiri Grichanov et Negrobov, 2014