4. Bombus (Subterraneobombus) difficillimus Skorikov

(Fig. 7)

Bombus difficillimus Skorikov, 1912:609, syntype queen ZISP examined.

Material examined. 1 worker (IAB).

Distribution in Gansu. Rare at high altitude in the northwestern Qilianshan mountains (Fig. 7); 1 locality 3656 m (IAB).

Distribution in China. Gansu, Qinghai (IAB).

Forage plants. FABACEAE: Hedysarum tanguticum .