Bombus waltoni Cockerell

Williams, Paul H., Huang, Jiaxing, Rasmont, Pierre & An, Jiandong, 2016, Early-diverging bumblebees from across the roof of the world: the high-mountain subgenus Mendacibombus revised from species’ gene coalescents and morphology (Hymenoptera, Apidae), Zootaxa 4204 (1), pp. 1-72 : 28-33

2. Bombus waltoni Cockerell

( Figs 1 , 25 , 36, 40 , 57 )

[ Bombus mendax Gerstaecker ; Morawitz 1887:199, misidentification.]

< Bombus mendax > subsp. chinensis Skorikov 1910b (February) :330 (not of Morawitz 1890:352, = B. chinensis (Morawitz)) , type-locality citation (Cyrillic) ‘[Mountains of Sining and Burkhan Budda]’. Lectotype queen by present designation ZISP examined, ( Cyrillic ) ‘[ Sinin mts]’ ( Xining range, Qinghai, China). Note 1. Synonymy with Bombus waltoni Cockerell implied when Bombus waltoni Cockerell was synonymised with Bombus mendax ssp. chinensis Skorikov by Skorikov in Cockerell (1911).

Bombus waltoni Cockerell 1910 (September) :239, type-locality citation ‘Khamba Jong, Sikkim’. Holotype queen by monotypy NHM examined, ‘ Khamba Jong’ (Gamba Dzong, Xizang, China). Note 2.

Bombus waltoni Cockerell; Cockerell 1911 :176; Wu 1941:281.

[ Bombus waltoni var. kozloviellus Skorikov 1912:608 , infrasubspecific.]

Bombus rufitarsis Friese 1913:85 , type-locality citation ‘Zentralasien’. Lectotype queen (not a worker) MNHU examined, ‘ Mongolei , Monda’ believed incorrect (probably Qinghai, China). Note 3. Synonymised with Bombus waltoni Cockerell by Skorikov (1914).

Mendacibombus waltoni (Cockerell) ; Skorikov 1914:125; Skorikov 1923:149.

Bombus asellus Friese 1924:438 , type-locality citation ‘ Mongolei bei Tippeti’ believed incorrect (probably Qinghai, China). Syntype workers and male MNHU not found by F. Koch and not seen (but taxon identity not in doubt). Regarded as conspecific with Bombus waltoni Cockerell by Bischoff (1936).

Bombus (Mendacibombus) waltoni Cockerell ; Richards 1930:633; Tkalců 1961:369; S.- F. Wang 1982:430; P.H. Williams 1991:42; S.- F. Wang 1992:1424; S.- F. Wang & Yao 1996:303; P.H. Williams 1998:100; P.H. Williams 2004:no. 30; Burger et al. 2009:462; Cameron et al. 2007:165; P.H. Williams et al. 2009:129; P.H. Williams et al. 2010:124; An et al. 2011:6; An et al. 2014.

Mendacibombus chinensis ( Skorikov); Skorikov, 1931 :fig. 20.

Bombus (Mendacibombus) waltoni chinensis Skorikov ; Bischoff 1936:17.

Note 1 ( chinensis ). Skorikov’s original description of the taxon chinensis cites two mountain ranges (Xining and Burhan Budai mountains) distant from one another (and both credible) as the type locality of the taxon chinensis , so that there is likely to have been more than one original syntype . The ZISP collection studied by Skorikov contains a queen that agrees with the original description and carries the labels: (1) gold disc; (2) white, handwritten (Cryrillic) ‘[[illegible] Sinin mts / [before]] 30.v.90 / [Gr. Grzmailo]’; (3) white, printed (Cyrillic) ‘[k. Skorikova]’; (4) red, handwritten ‘ Lectotypus Bombus / mendax subsp. / chinensis Skor. / design. Podbolotsk. ’ (M. Podbolotskaya, unpublished); (5) green, printed ‘ Mendacibombus / MD# 3521 det. PHW’; (6) red, printed ‘ LECTOTYPE [female] / Bombus mendax ssp. / chinensis / Skorikov, 1910 / det. PH Williams 2012’; (7) white, printed ‘[female] Bombus / ( Mendacibombus ) / waltoni / det . PH Williams 2012’. This specimen, which is complete, is regarded as one of Skorikov’s syntypes and is designated here as the lectotype in order to reduce uncertainty in the identity and application of the name.

Note 2 ( waltoni ). The original publication specifies that there was only one type specimen of waltoni by Cockerell, so the single specimen in the NHM collection labeled ‘Khamba Jong’ is regarded as the holotype by monotypy ( ICZN, 1999: Article 73.1.2).

Note 3 ( rufitarsis ). Friese’s original description of the taxon rufitarsis lists four workers, although the queen described here is labelled as a worker by Friese. The MNHU collection studied by Friese contains a queen that agrees with the original description and carries the labels: (1) white, printed ‘ Mongolei / Monda / 6. 0 8 / Weiske’ ; (2) white, handwritten by Friese ‘ Bombus / rufitarsis / [worker] 1909 Fr. Det.’; (3) maroon, printed ‘ Type’ ; (4) white, handwritten by Friese ‘ B.? / pyrosoma / [worker] 1900 Friese Fr. Det.’; (5) white, handwritten by Tkalců ‘ LECTOTYPE / Bombus / rufitarsis Friese / [female] Tkalců det.’ (B. Tkalců, unpublished); (6) white, printed ‘ Zool. Mus . / Berlin’; (7) green, printed ‘ Mendacibombus / MD# 3538 det. PHW’; (7) red, printed ‘LECTOTYPE [female] / Bombus / rufitarsis / Friese, 1913 / det. PH Williams 2012’; (8) white, printed ‘[female] Bombus / ( Mendacibombus ) / waltoni / det. PH Williams 2012’. This specimen, which is complete, is regarded as one of Friese’s syntypes and is designated here as the lectotype in order to reduce uncertainty in the identity and application of the name. For the same reasons as given in note 1 on B. superbus , we interpret the origin of the lectotype and the type locality as most likely to have been in Qinghai . Even so, the precise type locality remains very uncertain and consequently no location for the lectotype is shown on our map.

Etymology. The species is named after H. Walton, the medical officer during the 1904 British expedition known as the Tibet Frontier Commission with F. Younghusband as Commissioner. According to the specimen labels, in 1904 Walton collected at least two specimens of the species between Phari and Gyangzê (NHM). In July 1903 the previous expedition of the Commission, which was also led by Younghusband, visited Gamba Dzong ( Hopkirk 1982), just north of Sikkim. This is the locality where the type specimen was collected, but it is unclear who collected the holotype.

Taxonomy and variation. This species shows two principal colour patterns of the hair: extensively black, but with either an extensive orange tail, or with a black tail. The orange-tailed pattern matches the original description of the taxon waltoni . Both colour patterns are unique within the subgenus. No specimens of this species have distinct pale bands on the thorax and none has yellow hair anywhere on the body. Specimens of the species from the Kunlun (MD#3868, 3869) and Tanggula (MD#4132‒4137) mountains have the hair of the thoracic dorsum and T1 black and of T2‒5 orange, and are unusual for the species because the hairs are mostly not white-tipped. A specimen from the far west of the range in Ladakh (MD#4023) has no white hairs at all and T2 is predominantly orange. In the east and south, individuals of this species usually have many white-tipped hairs and often have intermixed white hairs (e.g. MD#193). Sometimes T1 has many white hairs intermixed and T2‒ 5 may have white hairs in the posterior quarter of each tergum (e.g. MD#1284). Some males (and according to Friese’s description, some workers, although we have not seen examples of these) in the northern and eastern areas of the distribution have little or no orange hair on the metasomal terga (Friese’s taxon asellus ), although all males share the same form of the genitalia and similar COI sequences ( Fig. 13 : the orange-tailed taxon waltoni s. str. MD#1482 and the black-tailed taxon asellus MD#300). The form of the male genitalia is diagnostic.

COI sequences show two principal groups of haplotypes, although these do not coincide with known morphological or colour-pattern differences. The majority of individuals are in one group. The second divergent group (differing in at least 12 nucleotides) of three individuals (MD#267, 1482, 1483) is from a narrow region in the south, associated with the Himalaya (from Nepal and from the Yadong region of Xizang, the region of the type of the taxon waltoni s. str.). The latter sequences are all short, perhaps because there are also nucleotide changes in the primer region. When fresh material becomes available from the Himalayan population and a specific primer can be developed, this group needs to be checked in case it represents a separate cryptic species.

FIGURES 36‒55 . (Continued) FIGURES 36‒55 . (Continued) Diagnostic description. Wings nearly clear. Hair long, uneven and slightly sparse. Female hair colour pattern: generally black, but the thoracic dorsum often with many grey-white hairs intermixed with black, on the side of the thorax and on T1 and on T2 anteriorly the black hairs often have white tips (cf. all other Mendacibombus species), on T2 posteriorly and on T3‒6 the predominantly orange hairs often have white tips, T6 with few black hairs. Hindleg tibia with the corbicular fringes with black and orange hairs, many with white tips. Female morphology: labrum with the basal depression narrow, the transverse ridge very broad and high, medially not subsiding or interrupted and in the median third shining with very few scattered large punctures, lateral tubercles almost without punctures. T2 at most (in queens) with only a very subtle posteriorly-directed convexity of its median posterior edge (cf. B. convexus ). Male morphology: beard of the mandible long, dense and black; genitalia ( Fig. 25 ) with the volsella at its broadest near the midpoint of its length, the dorsal surface just distal to this point with a raised curved ridge, often with small teeth, just inside the inner margin, running for 0.5× the remaining distal length of the volsella; volsella distally sharply acute (pointed) and curled back dorsally and anteriorly. Gonostylus length 1.25× its greatest breadth. Penis-valve head length 0.33× the length of the penis valve distal to the broadest point of the spatha.

Material examined. 29 queens 296 workers 56 males, from China, India, and Nepal ( Fig. 57 : IAR, INHS, IZB, MNHU, MSI, NHM, NME, OLL, PW, RMNH, SC, YT, ZISP), with 14 specimens sequenced (interpretable sequences listed in Figs. 11–13 ).

Habitat and distribution. Flower-rich alpine grassland, at elevations 2604‒(3927)‒ 5220 m a.s.l.. A species of the east Qinghai-Tibetan plateau, in the east Himalayan, Hengduan, and Qinghai-Gansu mountains, including the Tanggula Shan, Kunlun Shan, Burhan Budai Shan, Qinghai Nan Shan, Qiliang Shan, and Min Shan, but much rarer in the western Himalaya. The lack of records in the northwest Tibetan plateau ( Fig. 57 ) may at least in part reflect a lack of sampling (see the comments on B. superbus ) or may reflect a true absence (P.H. Williams, Bystriakova, et al. 2015) from a semi-arid region (the Qiangtang plateau, although modelling climate suitability shows that areas near the centre near Siling lake might be suitable). Compared to B. convexus , distributions of the two species overlap broadly, but B. waltoni extends further to the north and west and tends to occur at higher elevation (and it is uncommon for the two species to occur together at a site). Bombus waltoni replaces the western B. himalayanus in the wetter meadows of the higher alpine zone of the eastern Himalaya, where it overlaps with B. superbus in the Hohxil and the Tanggula mountains. Regional distribution maps are available for Sichuan (P.H. Williams et al. 2009), Gansu (An et al. 2011; An et al. 2014), and Nepal (P.H. Williams et al. 2010).

Food plants. Williams et al. (2009), An et al. (2011; 2014).

Behaviour. Mate-searching males perch on bare patches of ground or low bushes and pursue other bees that fly past before the males return to the same perch (PW: Fig. 1, 5 .viii. 2002, 3764 m Aba-Hongyuan road, Sichuan, China; 29.viii. 2009, 3914 m Diebu , Gansu, China).

Figures

FIGURE 13. Assigning names to species from an estimate of phylogeny for 130 COI sequences of the subgenus Mendacibombus. Based on a BEAST analysis of the 30 unique haplotypes (Fig. 11), with the remaining sequences interpolated back into the tree with 0 branch lengths from their matching samples (where a sequence matches more than one longer sequence within a species in the Collapse results, it is added after the first matching sequence, with the addition of the two short-sequence yellow unbanded specimens from Pakistan, MD # 4058, 4059). The sequence labels follow the format used in Figs 11, 12. Lineages accepted as species from the GMYC models (Fig. 11) are shown as thick branches, the most recent common ancestors of each species are shown with a black spot, and branches within species are shown as thin branches. Asterisks mark samples used as informal proxies for the type specimens of each of the taxon names (Table 1). The proxy sample for the type specimen for the oldest available name (the valid name) for each species (from Fig. 11) is marked in bold. The interpretations of the species with their valid names are shown in grey to the right.

FIGURES 1 ‒ 6. Views of perching males of species of the subgenus Mendacibombus, showing the anteriorly extended antennae and laterally extended wings that are characteristic of their form of male mate-searching behaviour: 1, B. waltoni at Diebu ca 3910 m, Minshan mountains, Gansu, China, 29. viii. 2009; 2, B. convexus at Diebu ca 3340 m, Minshan mountains, Gansu, China, 29. viii. 2009; 3, B. avinoviellus at Gulmarg ca 2700 m, Pir Panjal mountains, Kashmir, India, 16. viii. 1985; 4, B. himalayanus at Apharwat ca 4100 m, Pir Panjal mountains, Kashmir, India, 30. viii. 1986; 5 ‒ 6, B. margreiteri near Dulan ca 3520 m, Burhan Budai mountains, Qinghai, China, 31. viii. 2010. Photos by PW (Figs 3 – 4 are the best available for these species).

FIGURES 24 ‒ 35. Morphology of the male genitalia for species of the subgenus Mendacibombus from the dorsal aspect, anterior to the left of the image, posterior to the right: 24, B. superbus, China MD # 339; 25, B. waltoni, China MD # 216; 26, B. convexus, China MD # 215; 27, B. makarjini, Kazakhstan MD # 1240; 28, B. marussinus, Pakistan MD # 408; 29, B. avinoviellus, India MD # 404; 30, B. himalayanus, India MD # 426; 31, B. turkestanicus, China MD # 351; 32, B. defector, Kyrgyzstan MD # 367; 33, B. margreiteri, China MD # 294; 34, B. handlirschianus, Russia MD # 835; 35, B. mendax, Spain MD # 689.

FIGURES 36 ‒ 55. Morphology of parts of the male genitalia from the dorsal aspect of the left side, anterior to the left of the image, posterior to the right, white bars indicating morphological characters referred to in the key to males: 36, B. waltoni; 37, B. mendax; 38, B. superbus; 39, B. convexus; 40, B. waltoni; 41, B. convexus; 42, B. defector; 43, B. mendax; 44, B. mendax; 45, B. turkestanicus; 46, B. avinoviellus; 47, B. mendax; 48, B. mendax; 49, B. makarjini; 50, B. handlirschianus; 51, B. himalayanus; 52, B. turkestanicus; 53, B. himalayanus; 54, B. himalayanus; 55, B. marussinus.

FIGURES 56 ‒ 67. Maps of the global distributions of species of the subgenus Mendacibombus from the material examined, with grey spots for specimen records and black spots for the samples with COI sequences (each species is unknown from regions outside the map boundaries shown); grey crosses for records of all species of Mendacibombus combined. Relief map with hill shading, Cartesian orthonormal projection, grey lines show borders to national administration according to UN maps, north at the top of the map. Image created in ArcGIS using World _ Shaded _ Relief basemap © 2014 Esri.

FIGURES 11 ‒ 12. Recognising species from an estimate of phylogeny for 30 unique COI haplotypes of the subgenus Mendacibombus by BEAST, using GMYC models and the PTP procedure. From the GMYC models (11), the single threshold T is shown by the vertical grey bar so that the intersecting lineages are interpreted as indicating 12 separate species (black spots at coalescent nodes; outgroups not shown). Values below the nodes of the maximum clade-credibility tree are Bayesian posterior probabilities showing branch support (groups with values <0.8 are considered unreliable) from the BEAST analysis with two billion MCMC generations and a 1 % burn-in. The x - scale axis is calibrated in substitutions per nucleotide site. From the PTP procedure (12), the Bayesian PTP solution with highest support also indicates 12 species. Values above the nodes are PTP Bayesian support values that all daughter haplotypes are parts of a single species; values below the nodes are Bayesian posterior probabilities showing branch support. The scale bar is calibrated in substitutions per nucleotide site. Each unique haplotype is represented by one of the longest available sample sequences, labelled with: the sequence length in number of base pairs, a taxon name or name for an unpublished colour pattern (light / dark / yellow / white / pale), and then a code that consists of a specimen identifier (MD #) from the project database and (after the hyphen) a sample identifier from BOLD or from GenBank, followed with its geographic origin.