See: The Bumblebees of North China (by AN ET AL), p11: Key to the species of the genus Bombus known from North China for females:
-Hind tibia with the outer surface strongly and uniformly convex and uniformly densely covered with moderate to long stout hairs throughout, the fringing hairs often poorly differentiated and not forming a pollen basket (corbicula), the inner distal margin without a comb of stout spines (rastellum); S6 with ventro-lateral keels . . . . . . . . . . . .45 Psithyrus
and then B. coreanus is the only species of this subgenus living in this area, and it looks very like B. ignitus.