31. Bombus (Thoracobombus) impetuosus Smith s. l.

(Figs 64, 65)

BOMBUS IMPETUOSUS Smith, 1871:249.

Bombus Potanini Morawitz, 1890:350 .

Bombus silvarum var. subrufescens Friese, 1913:87 . Bombus (Agrobombus) yuennanensis Bischoff, 1936:14 . Bombus (Agrobombus) combai Tkalců, 1961:357 .

Taxonomy. For a discussion of the taxonomy of this species see Williams et al. (2009). Assessment of COI barcodes supports this interpretation.

Material examined. 3 queens, 169 workers, 14 males (IAB).

Distribution in North China. Only on the edge of the east Qinghai-Tibetan plateau and the southwest loess plateau. Common at high elevations of the Zhagana nature reserve, at medium elevations of the Lianhuashan nature reserve, the Xinglongshan nature reserve, the Liancheng nature reserve in southwestern Gansu, and at medium elevations of the Liupanshan nature reserve in southern Ningxia and eastern Gansu. Rare at medium elevations of the Baishuijiang nature reserve in southernmost Gansu. 45 localities (Fig. 64) between 1716–3524 m (IAB).

Variation in North China. This species shows strong variation in the colour of the pale hair bands in China but shows little variation in North China (Fig. 65).

Similar species in North China. This species is similar in its grey-banded colour pattern to B. lepidus (see the key; Fig. 65, 105).

Distribution in China. Chongqing, Sichuan, Yunnan, Xizang, Gansu, Qinghai, Ningxia (IAB).

Forage plants. ASTERACEAE: Arctium lappa, Cirsium leo, Saussurea pulchella, S. stella, Saussurea sp., Senecio jacobaea, Sinacalia tangutica; BORAGINACEAE: Myosotis sp.; CAMPANULACEAE: Adenophora potaninii; FABACEAE: Astragalus bhotanensis, Melilotus officinalis, Oxytropis kansuensis, O. ochrocephala; GENTIANACEAE: Halenia elliptica; LAMIACEAE: Caryopteris incana, Dracocephalum heterophyllum, D. isabellae, Nepeta prattii, Salvia przewalskii, Salvia sp., Thymus mongolicus; PAPAVERACEAE: Corydalis sp.; RANUNCULACEAE: Aconitum carmichaelii, A. gymnandrum, A. leucostomum, Clematis tangutica; SCROPHULARIACEAE: Euphrasia pectinata, Pedicularis kansuensis, P. spicata, Pedicularis sp.