10. Bombus (Alpigenobombus) grahami (Frison, 1933)

Figs 9, 94‒103, 115

Bremus (Alpigenobombus) grahami Frison, 1933 [[30] September]: 334. Note 1.

Alpigenobombus beresovskii Skorikov, 1933a [30 September: Pesenko & Astafurova 2003]: 248. Syn. nov.

Bombus Alpigenobombus grahami [subsp.] melani Wang & Yao, 1993: 422 . Syn. nov.

Alpigenobombus (Alpigenobombus) beresovskii ‒ Skorikov 1923: 156, published without description or indication, unavailable name.

Alpigenobombus berezovskii ‒ Skorikov 1931: 204, published without description or indication, unavailable name.

Bremus (Alpigenobombus) grahami var. [not subsp.] ordinatus ‒ Frison 1935: 353, infrasubspecific.

NOTE 1. Acceptance of B. grahami as the valid name in preference to B. beresovskii follows Williams (2022a) as the First Reviser (ICZN 1999: Article 24). Bombus grahami is the name in most widespread use for this species in the literature.

Species-taxon concept and variation

The taxon concept of the species B. grahami here is modified from the long-standing interpretation (Williams 2022a), in that it includes the taxon beresovskii, based on: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 12); corroborated by (2) diagnostic morphological character states (see the keys).

The PTP and morphological results (Fig. 12, keys) support the interpretation that the divergent colour patterns of the taxa grahami s. str. and beresovskii are conspecific (Williams 2022a). The available COIbarcode-like sequences may all be low-divergence neonumts (Fig. 11). From morphology, the taxon melani (holotype queen Fig. 99) is closely similar to the taxon beresovskii (syntype queen Fig. 100).

For the typically coloured individuals of B. grahami, the wings of the males are (unusually among bumblebees) much paler than the wings of the females. The wings are also slightly paler for females of the taxon beresovskii (males not seen).

Some females with the beresovskii colour pattern (from northern Sichuan: Figs 99–100) have a dark colour pattern that resembles B. angustus, but others (from Shaanxi: Fig. 98) have a light colour pattern that resembles B. validus . One worker (Fig. 98) has a distinct band of grey hairs fringing the thoracic dorsum anteriorly and posteriorly with some grey hairs along the midline. Males of the taxa beresovskii and melani are unknown to us.

Bombus grahami females, with the grey-thorax colour pattern in the west (Himalaya) and centre (Hengduan) of its range (Figs 94‒97), appear to mimic the commoner B. (Orientalibombus) funerarius Smith, 1852 (Williams 2007: fig. 5g). In contrast, the more extensively black-thorax colour pattern in the north-east (in the hills to the north of the Sichuan Basin: Figs 98‒100) appears to mimic the abundant B. (Melanobombus) pyrosoma (Williams 2007: close to fig. 5m). Some of these females (Fig. 98) resemble closely B. validus (Figs 70‒71) in colour pattern, but can be distinguished easily by the shorter oculo-malar distance of B. grahami .

Type material

Bremus (Alpigenobombus) grahami Frison, 1933 [[30] September]: 334. Holotype by original designation: ♀ (worker) Sichuan, China (USNM). Examined .

Alpigenobombus beresovskii Skorikov, 1933a [30 September: Pesenko & Astafurova 2003]: 248.

Syntype (unpublished Podbolotskaya lectotype): ♀ (queen) Sichuan, China (ZIN). Examined .

Bombus (Alpigenobombus) grahami [subsp.] melani Wang & Yao, 1993: 422 .

Holotype by original designation: ♀ (queen) Henan, China (IOZ). Examined.

Morphological diagnosis

Female

Wings very darkly clouded with brown with the veins dark brown, hair short, oculo-malar area shorter than broad, clypeus in its central area with only a few large and small widely-spaced punctures (cf. B. breviceps); hair of the thoracic dorsum black, either usually with many grey hairs intermixed so as to appear silvery olive-grey, with the majority of the hair along the longitudinal midline white, or if entirely black, then T3 predominantly orange-red.

Male

Wings nearly clear with the veins dark brown, hair short; genitalia (Fig. 115) with the gonostylus half as long on its outer side than on its inner side with the distal lobe slightly reduced and broadly flattened, appearing as a triangular pointed inwardly-projecting process only from the inner aspect (cf. B. genalis, B. breviceps); hair of the thoracic dorsum yellow, often between the wing bases with many black hairs intermixed.

Material sequenced in Fig. 12

CHINA • 1 ♀ (queen); Sichuan, Taoyuan; 32.6924° N, 106.8336° E; 21 Sep. 2011; PW seq: PWB01; IAR: AG#001 • 1 ♀ (worker); Yunnan, Lijiang; 27.0156° N, 100.1714° E; 12 Jul. 2017; H. Liang leg.; KIB seq: KIB030; KIB: AG#076 .

Additional sequences in Fig. 10 and haplotype duplicates

BHUTAN • 1 ♀ (worker); Thimpu, Dochu-La; [27.4898° N, 89.7504° E]; 7 Jul. 1996; L. Blommers leg.; BOLD seq: 6880H10; RMNH: AG#094 .

CHINA • 2 ♀♀ (workers); Yunnan, Lijiang; 27.0156° N, 100.1714° E; 2 Aug. 2017; H. Liang leg.; KIB seq: KIB092, KIB097; KIB: AG#075, AG#077 • 2 ♀♀ (workers); same collection data as for preceding but 12 Aug. 2017; KIB seq: KIB116, KIB032; KIB: AG#078, AG#079 • 1 ♀ (worker); Sichuan, Meigu; 28.329° N, 103.129° E; GenBank seq: FJ175354; SC: AG#096 • Yunnan, Yulong Snow Mountain; [27.047° N, 100.261° E]; H. Liang leg.; GenBank seq: MT906009; KIB: AG#150 .

INDIA • 1 ♀ (worker); Arunachal Pradesh, 1300 m E of Lama Tukkut; 28.9949° N, 95.2926° E; 30 Aug. 2017; NCBS seq: BE782; NCBS: AG#203 .

NEPAL • 1 ♁; Janakpur, Dongo Kharka; 27.9022° N, 86.2865° E; 23 Aug. 1983; I. Kudo leg.; BOLD seq: 1551H05; SEHU: AG#119 .

Global distribution

Himalaya, Hengduan, and into Central China: Nepal, India (Sikkim, Arunachal Pradesh), China (Xizang, Yunnan, Sichuan, Gansu, Shaanxi, Chongqing, Hubei, Henan, Guizhou): IAR, IOZ, KIB, NCBS, NHMUK, PW, RMNH, SEHU, USNM, ZIN.

This species is recorded at elevations of 2650‒2800 m in the Himalaya (Williams et al. 2010; Streinzer et al. 2019), and 858‒3040 m in the Hengduan and in Shaanxi (Williams et al. 2009; An et al. 2014). Bombus grahami is active in open areas in the middle and upper forest zones, but also inside the forest. Individuals with a black-thorax colour pattern (taxon beresovskii) occur in the hills to the north of the Sichuan basin, where they appear to be extremely rare (only three queens and three workers have been examined: IAR, IOZ, PW) and are not known to co-occur with individuals with the olive-thorax colour pattern (although many more data are needed to clarify the situation).

Behaviour

Male eye slightly enlarged relative to female eye, male mate-searching behaviour unknown.