Bombus (Pyrobombus) hengduanensis Williams, Ren & Xie, 2022

Williams, Paul H., Dorji, Phurpa, Ren, Zongxin, Xie, Zhenghua & Orr, Michael, 2022, Bumblebees of the hypnorum-complex world-wide including two new near-cryptic species (Hymenoptera: Apidae), European Journal of Taxonomy 847, pp. 46-72 : 63-65

Bombus (Pyrobombus) hengduanensis Williams, Ren & Xie sp. nov.

urn:lsid:zoobank.org:act:4D8DB502-0822-4A83-BB73-2F1F869F3EA2

Figs 1–2 , 32‒38 , 52

[ Bombus (Pyrobombus) hypnorum ( Linnaeus, 1758) – Williams et al. 2009b: 157, (in part) misidentification.]

Diagnosis

Female

Distinguished by the combination: labral tubercle on its broad outer lateral and anterior-facing surface in the centre with a few very large punctures scattered throughout; clypeus in the central area with a longitudinal band of small punctures and with very large punctures some spaced by just twice their own diameter; ocello-ocular area along the inner eye margin with a broad band of close small and medium punctures; T4 hair either black in the posterior half or with only a few white hairs along the posterior margin; T5 posteriorly in the middle anterior to the smooth posterior margin with a narrow band of large punctures extending for less than an eighth of the length of the tergum.

Male

Distinguished by the combination: hair variable, from the thorax and metasomal T1‒2 brown and T3‒4 black, to T1‒4 black.

Etymology

Named for its occurrence in the Hengduan mountain region (in the provinces of Yunnan and Sichuan).

Material examined

Holotype CHINA • ♀ (queen), pinned; [four labels]; [(1) white printed in black] ‘RWM101074’; [(2) green printed in black] ‘C1iBES221’; [(3) white printed in black] ‘CHINA, Xizang / Ranwu Lake 3910 m / 29.4849°N 96.6425°E / 24.vii.2018 Z. Ren’; [(4) red printed in black] ‘HOLOTYPE ♀ (q) / Bombus hengduanensis / Williams, Ren & Xie / det PH Williams 2022’; IOZ.

Other material sequenced or examined

CHINA • 1 ♀ (worker); Sichuan, Zhegu Shan ; 31.852° N, 102.672° E; alt. 4180 m; 2 Aug. 2002; P. Williams leg.; BOLD-1550A04 ; PW • 1 ♀ (worker); Sichuan, Zhegu Shan ; 31.852° N, 102.672° E ;

alt. 4180 m; 2 Aug. 2002; P. Williams leg.; BOLD-1550A05 ; PW • 1 ♀ (queen); [in Chinese : Yunnan, Zhongdian County]; 20 Aug. 1981; PW • 1 ♂; [in Chinese : Yunnan, Dêqên County]; alt. 4200 m; 30 Jul. 1982; PW • 1 ♂; Xizang, Sijilashan ; 29.6416° N, 94.6982° E; alt. 4019 m; Z. Ren leg.; KIBSJLSM101010; KIB • 1 ♀ (worker); Xizang, Sijilashan ; 29.6416° N, 94.6982° E; alt. 4019 m; Z. Ren leg.; KIB-SJLSM101011; KIB • 1 ♀ (worker); Xizang, Sijilashan ; 29.6416° N, 94.6982° E; alt. 4019 m; Z. Ren leg.; KIB-SJLSM109001; KIB • 1 ♂; Xizang, Honglashan ; 29.2245° N, 98.6785° E; alt. 3909 m; Z. Ren leg.; KIB-HLSM201008; KIB • 1 ♀ (worker); Xizang, Zhujiaolashan ; 31.1088° N, 96.8847° E; alt. 3953 m; Z. Ren leg.; KIB-ZJLSM201032; KIB • 1 ♀ (worker); Xizang, Zhujiaolashan ; 31.11821° N, 97.0175° E; alt. 4029 m; Z. Ren leg.; KIB-ZJLSM301018; KIB .

BURMA • 1 ♂; Adung valley ; alt. 3658 m; 23 Jun. 1931; F. Kingdon-Ward leg.; NHMUK .

Description

Female

Habitus illustrated in Fig. 52 , body size small (queen body length 13‒15 mm, worker 10‒11 mm), hair (pubescence) moderately long, wings very lightly clouded with brown. Mandible with the distal notch anterior to the posterior tooth (incisura) very shallow. Oculo-malar area (‘cheek’ sensu Williams et al. 2014; not the gena) of medium length, 1.0 × as long as the breadth of the mandible at its base (length measured between the ventral edge of the compound eye and the edge of the malar area at the articulation of the mandible midway between the mandibular condyles; breadth measured between and including the mandibular condyles). Labral tubercle on its broad outer lateral and anterior-facing surface in the centre with a few very large punctures scattered throughout. Clypeus weakly swollen, its raised area nearly flat, the central area with few widely scattered large, medium, punctures with intervening areas shining, with a longitudinal band of small punctures. The area between the inner edge of the compound eye and the outer edge of the lateral ocellus occupied in just more than its outer third by closely spaced medium and small punctures, the medium punctures scattered across this band. Mid basitarsus with the distal posterior corner broadly rounded; hind tibia outer surface with a corbicula, the surface sculpturing weakly reticulate so that the surface appears slightly matt; hind basitarsus in the distal three quarters covered with short branched decumbent and weakly overlapping hairs with golden reflections. Metasomal T6 posteriorly rounded and not divided medially, with a small subapical dorsal boss. Colour pattern of the hair of the body predominantly black. Head black except for orange hairs anteriorly on the labrum and laterally on the mandibles and a short hair brown on the top of the head around the ocelli. Thoracic dorsum bright orange-brown, this pale hair extending half way down the side of the thorax anteriorly, without black hair between the wing bases or scattered; the front, middle and hind leg tibiae all with the hairs black, the basitarsi all with the integument brown-black like the tibiae. Hair of T1 and T2 anteriorly orange-brown, T2 posteriorly and T3 and T4 anteriorly black, T 4 in either posterior half black or with only a few white hairs along the posterior margin, and T5‒6 white.

Male

Body size small (body length 11‒13 mm), hair (pubescence) moderately long, wings very lightly clouded with brown. Colour pattern of the hair of the body predominantly black. Front and top of the head with short hair brown. Thoracic dorsum bright orange-brown, this pale hair extending half way down the side of the thorax anteriorly, without black hair between the wing bases or scattered; the front, middle and hind leg tibiae all with the hairs black, the basitarsi all with the integument brown-black like the tibiae. Hair of metasomal T1‒4 black or sometimes T1, or sometimes T1‒2 brown, T5‒7 with at least some white, but sometimes predominantly black. Male genitalia with the gonostylus nearly triangular, the inner anterior (basal) projection separated from the gonocoxa by a distance less than the breadth of the recurved hook of the penis-valve head; the volsella scarcely projecting beyond the gonostylus; the penis valve with the head recurved as a flattened sickle-shaped hook that is scarcely tapering at the mid point of its length.

Distribution

In the mountains of the eastern Qinghai-Tibetan Plateau, extending into Sichuan, Yunnan, and Burma, at elevations of 3600‒4200 m (Williams et al. 2009). From their distribution and the colour pattern of the hair, this is likely to be the species that occurs slightly further north in North China ( An et al. 2014: at elevations of 780‒2923 m), extending eastwards from Gansu through the Qin mountains to Ningxia, Shaanxi, and Shanxi, although it is not possible to confirm this here from barcode sequences. Uniquely for species pairs within the hypnorum -complex, this species shows an overlap in distribution range with B. wolongensis in Sichuan and Yunnan.

Figures

Fig. 1. MRBAYES estimate of phylogeny as a metric tree (outgroup B. alpinus (Linnaeus, 1758) not shown) from COI barcodes from GenBank and BOLD databases for the vagans-group and hypnorum- group, with additions from the authors for the hypnorum-group of bumblebees, filtered to remove duplicate and short sequences. Each sequence is labelled with: sequence length; a taxon name from the database; a code consisting of a sequence identifier from the project database and a specimen identifier from the online database; its country and (for larger countries) state or province). The scale bar is calibrated in substitutions per nucleotide site. Results of Bayesian Poisson-tree-process (PTP) models applied for assessing support for species’ gene coalescents by maximum likelihood are shown as PTP scores above the branches: scores approaching 1 and where branches change from blue to red indicates are where the most likely species’ gene coalescents are detected. Asterisks mark sequences used as informal proxies for the type specimens of each of the taxon names in Table 2.

Fig. 2. Distribution of barcoded samples of the hypnorum-complex and B. perplexus Cresson, 1863, with the interpretations as separate candidate species from Fig. 1 shown as different coloured spots as per the colour key on the left. Relief map with hill shading, polar projection (north pole shown as a star), the international boundaries and the Arctic Circle are shown as narrow grey lines, and the northern tree line shown as a broad grey line. Image created in ArcGIS using World_Shaded_Relief basemap (© 2014 Esri).

Figs 3–38. Simplified diagrams for the colour patterns of the hair on the dorsum for ♀♀ (left) and ♂♂ (right) of the Bombus species from Fig. 2. The dorsum is divided into regions, each of which shows only the predominant or most apparent colour for that region using a simplified colour palette (precise shades vary), with olive indicating a mixture of black and yellow hair, and grey indicating a mixture of black and white hair.

Fig. 52. Bombus hengduanensis Williams, Ren & Xie sp. nov., ♀ (queen), holotype (IOZ), habitus, lateral view (image reversed). Scale bar: 10 mm.