Bombus (Alpinobombus), Skorikov, Skorikov

Key to Alpinobombus species for females

1 Cheek <1.25× longer (oculo-malar distance) than broad (breadth of the mandible at its base between and including condyles) ( Fig. 140 View FIGURES 140‒143 )........................................................................................... 2

- Cheek> 1.25× longer than broad ( Fig. 141 View FIGURES 140‒143 )................................................................ 5

2 (1) Hind tibia outer (corbicular) surface coarsely rough and matte with the microsculpture (surface texture) interrupting the reflective highlights ( Fig. 142 View FIGURES 140‒143 ); if the hair of T2 is extensively orange then there are often broad patches of black hairs in the anterior lateral corners, the orange often appearing faded ( Figs. 2 View FIGURES 1‒6 , 25‒31 View FIGURES 22‒38 )............................................... 3

- Hind tibia outer surface smooth and shining with the microsculpture scarcely or not interrupting the reflective highlights ( Fig. 143 View FIGURES 140‒143 ); if the hair of T2 is extensively orange then the orange hairs extend into the anterior lateral corners with almost no black hairs, the orange often bright ( Figs. 1 View FIGURES 1‒6 , 16‒17 View FIGURES 15‒21 )............................................................... 4

3 (2) Europe or Russia, hair of T3 either orange or black or both, rarely with yellow or grey hairs ( Figs. 2 View FIGURES 1‒6 , 23‒31 View FIGURES 22‒38 ) B. pyrrhopygus View in CoL

- North America or Greenland, hair of T3 black but often with many yellow or grey hairs either scattered in the middle third or in a posterior fringe or both ( Figs. 3 View FIGURES 1‒6 , 40‒51 View FIGURES 39‒58 )......................................................... B. polaris View in CoL

4 (2) Europe, hair of T2‒3 predominantly orange with no yellow ( Figs. 1 View FIGURES 1‒6 , 16‒17 View FIGURES 15‒21 )................................ B. alpinus View in CoL

- North America, hair of T2‒3 yellow or black with no orange ( Figs. 90‒100 View FIGURES 89‒103 )............................. B. neoboreus View in CoL

5 (1) North America, hair of T3 usually predominantly yellow for its entire breadth, sometimes with black hairs extensively inter- mixed, T4 either entirely black or at most with a few yellow hairs laterally ( Figs. 105‒111 View FIGURES 104‒115 )................ B. kluanensis View in CoL - North America or Europe or Russia, hair of T3 predominantly black, sometimes with a dense yellow posterior and/or lateral fringe, T4 either black or with patches of either orange or yellow or white ( Figs. 60‒70 View FIGURES 59‒76 , 78‒84 View FIGURES 77‒88 , 117‒118 View FIGURES 116‒123 , 125‒126 View FIGURES 124‒128 )....... 6

6 (5) Hair of T3‒6 either with some orange or white, or if completely black then either the side of the thorax (mesepisternum) is usually completely yellow or the thorax is entirely black (the worker caste is common) ( Figs. 60‒70 View FIGURES 59‒76 , 78‒84 View FIGURES 77‒88 )............. 7

- Hair of T3‒6 completely black and the side of the thorax is extensively black (the worker caste is extremely rare) ( Figs. 117‒118 View FIGURES 116‒123 , 125‒126 View FIGURES 124‒128 ).................................................................................... 8

7 (6) Europe or Russia, hair of the face (base of the antenna) black, the side of the thorax (mesepisternum) usually predominantly black, T3 usually completely black ( Figs. 4 View FIGURES 1‒6 , 60‒70 View FIGURES 59‒76 )................................................. B. balteatus View in CoL

- North America, hair of the face usually with some yellow, the side of the thorax usually predominantly yellow, T3 extensively black but usually with a broad posterior and lateral fringe of either yellow or orange (individuals from Ellesmere Island are darker like B. balteatus View in CoL ) ( Figs. 5 View FIGURES 1‒6 , 78‒84 View FIGURES 77‒88 ).......................................................... B. kirbiellus View in CoL

8 (6) Europe or Russia, hair of the pale bands usually dark chestnut brown (or pale yellow from Wrangel Island) ( Figs. 6 View FIGURES 1‒6 , 125‒ 126 View FIGURES 124‒128 )..................................................................................... B. hyperboreus View in CoL

- North America or Greenland, hair of the pale bands usually pale straw yellow ( Figs. 1 17‒118 View FIGURES 1‒6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURES 11‒13 View FIGURE 14 View FIGURES 15‒21 View FIGURES 22‒38 View FIGURES 39‒58 View FIGURES 59‒76 View FIGURES 77‒88 View FIGURES 89‒103 View FIGURES 104‒115 View FIGURES 116‒123 )................. B. natvigi View in CoL