5. Bombus (Subterraneobombus) difficillimus Skorikov

(Figs 12, 13)

Bombus difficillimus Skorikov, 1912:609 .

Taxonomy. Revised by Williams et al. (2011).

Material examined. 1 worker (IAB).

Distribution in North China. Only on the edge of the northeast Qinghai-Tibetan plateau, Very rare at high elevations of the Qilianshan nature reserve in Gansu. 1 locality (Fig. 12) at 3656 m (IAB).

Similar species in North China. This species is very similar in its black- and yellow-banded colour pattern to some B. melanurus (see the key; Figs 84, 85).

Distribution in China. Gansu, Qinghai, Xinjiang (IAB). Forage plants. FABACEAE: Hedysarum tanguticum .