Bombus superbus (Tkalců), Tkalcu

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 : 24-28

1. Bombus superbus (Tkalců)

( Figs 24 , 38 , 56 , 69 )

Mendacibombus superbus Tkalců 1968:22 , type-locality citation ‘Mongolei Monda’. Holotype queen by original designation MNHU examined, ‘ Mongolei , Monda’ believed incorrect (probably Qinghai or Xizang, China). Note 1. [ Bombus wagneri Tkalců, 1968:24 , published as a junior synonym.]

Bombus (Mendacibombus) superbus (Tkalců) ; P.H. Williams 1991:42; S.- F. Wang & Yao 1996:303; P.H. Williams 1998:99; P.H. Williams 2004:no. 29.

Note 1 ( superbus ). Tkalců’s original description of the taxon superbus cites ‘ Mongolei Monda 6. 0 8 Weiske’ as the type locality. The MNHU collection studied by Tkalců 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 / wagneri / [female] 1909 Friese Fr. Det.’ (H. Friese, unpublished); (3) maroon, printed ‘ Type’ ; (4) white, printed ‘Zool. Mus. / Berlin’ ; (5) red, printed ‘Holo- / typus . ’; (6) white, handwritten by Tkalců ‘ HOLOTYPE / Mendacibombus / superbus Tk. / [female] Tkalců det.’; (7) green, printed ‘ Mendacibombus / MD# 338 det. PHW’; (8) red, printed ‘ HOLOTYPE [female] / Mendacibombus / superbus / Tkalců, 1968 / det. PH Williams 2012’; (9) white, printed ‘[female] Bombus / ( Mendacibombus ) / superbus / det . PH Williams 2012’. This specimen, which is complete, is regarded as Tkalců’s holotype .

The type locality ‘ Mongolei / Monda’ and the style of the printed label appear to refer to collections made by the E. Weiske 1908 expedition ( Kerzhner 1972) near the relatively well known town of Mondy , Buryatia, near the Mongolian border ( Russia, 51.67281°N 100.98458°E, 1300 m). A. Ebmer (in litt.) also points to the information on G. Potanin’s itinerary in 1880 given by Komarov (1928) as evidence that these names both refer to the same place. However, the interpretation that the type locality of B. superbus is Mondy was challenged in the original publication by Tkalců (1968), because the spelling Monda was known to him for a locality in the mountains of western Nepal . A likely Nepalese site with this name could not be identified by us. The long hair of the holotype of B. superbus resembles the hair of other species from very high elevations (much higher than Mondy). This is consistent with the extreme habitat of the other known specimens of this species ( IAR, MD#4110‒4131; IZB, MD#339‒342), which are from above 4600 m in Qinghai and Xizang. The holotype specimen is in the H. Friese collection ( MNHU, MD#338), a collection that is known to have a number of bumblebee specimens with dubious locality data (see the notes on the nominal taxa rufitarsus and asellus under B. waltoni ). Ebmer (2008) has described how for other bees with ‘ Monda’ labels, while in some cases they appear to refer genuinely to Mondy, in other cases these labels appear to be spurious later additions and he discussed how this might have arisen. Ebmer suggests that Friese described some of the material collected by the V. Roborovski and P. Kozlov expeditions of the 1890s and that some specimens from these expeditions ended up erroneously with ‘ Monda’ labels. This seems likely in this case. Roborovski and Kozlov took part in expeditions that visited the eastern Qinghai-Tibetan plateau in the summers of 1879, 1880, 1884, 1894, and 1895 ( Bretschneider 1981). Therefore we interpret the origin of the holotype and the type locality as most likely to have been on the Qinghai-Tibetan plateau. Even so, the precise type locality remains very uncertain and consequently no location for the holotype is shown on our map.

Etymology. The species is named from the Latin superbus for its resplendent (‘prangend’) or sumptuous (‘prächtig’) appearance according to the original (German) description.

Taxonomy and variation. This species shows a single colour pattern of the hair with little variation. This is the pattern in the original description, which is unique within the subgenus. All known specimens of the species have a yellow-banded and none has a white-banded colour pattern. The males from the Tanggula mountains (MD#339, 4131) have the yellow anterior collar of the thoracic dorsum narrower, barely reaching posteriorly to the tegula, and with many black hairs intermixed, and the metasomal terga 4‒7 have many of the hairs white-tipped. The queens and workers are unusually large for species of this subgenus, although the males are similar in size to those of the other species. The form of the male genitalia is diagnostic.

Diagnostic description. Wings nearly clear. Hair long, uneven, and slightly sparse. Female hair colour pattern: ( Fig. 69 ) generally black, the head sometimes with some yellow hairs dorsally posterior to the ocelli, bright yellow hair in a transverse band in almost the anterior half on the thoracic dorsum and extending laterally and ventrally to just below the wing bases, and on metasomal T1‒2, although T2 with a few black hairs intermixed along the posterior margin, T3‒6 predominantly black with some white tips or sometimes a few hairs entirely white (cf. all other Mendacibombus species). Midleg basitarsus with the hair predominantly orange, with long black or orange hairs arising from the outer surface in the proximal third (more apparent in workers than queens); hindleg tibia with the corbicular fringes black, the posterior fringe with some hairs with orange tips or distally some hairs entirely orange (more for queens than for workers); hindleg basitarsus with the hair predominantly orange, with the long posterior fringe orange. Female morphology: labrum with the basal depression very narrow, the transverse ridge very broad and low, medially subsiding but not interrupted, with large punctures in the median third, lateral tubercles with few punctures. T2 without a posteriorly-directed convexity of its median posterior edge (even for the queens, cf. B. convexus ). Male morphology: beard of the mandible long, dense and black; genitalia ( Fig. 24 ) 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, just inside the inner margin, running for 0.5× the remaining distal length of the volsella; volsella distally a rounded right angle and barely curled back dorsally and not at all anteriorly.

Material examined. 3 queens 22 workers 2 males, from China ( Fig. 56 : IAR, IZB, MNHU), with 7 specimens sequenced (interpretable sequences listed in Figs. 11–13 ).

Habitat and distribution. Flower-rich alpine grassland, at elevations 4800‒(5167)‒ 5220 m a.s.l.. A species of the high Qinghai-Tibetan plateau, known so far definitely only from the Hohxilshan (= Kekexili; collected 1990, X.-Z. Zhang) within the eastern Kunlun mountain system and from the Tanggulashan (collected 2014, Z.-Y. Miao, Figs 69, 70 ) on the Xizang-Qinghai border. This apparent rarity could be explained by the very limited sampling for bumblebees at the highest elevations in the central and northern Qinghai-Tibetan plateau, because access in this region is difficult, with few roads. In this case, the mapped distribution in Fig. 56 could be a small part of the species’ true distribution, which could be broader, although patchy, at very high elevations. Alternatively, the map may be a more precise reflection of the species’ true distribution, limited by aridity (in the Qiangtang semi-arid area: C.-Z. Wang et al. 2013) to a few small patches in the central and northern mountain groups where there are sufficiently large permanent streams to provide water to sustain flower-rich grassland reliably throughout every summer (P.H. Williams, Bystriakova, et al. 2015). For example, suitable patches may occur around the large ice caps further west in the Tanggulashan. Bombus superbus may be one of the few truly endemic bumblebee species of the extreme habitats of the high Qinghai-Tibetan plateau. This species overlaps with B. waltoni in the Hohxil and in the Tanggula mountains.

FIGURES 24‒35 . (Continued) Food plants. ( Asteraceae ) Saussurea tibetica C. Winkler ; ( Gentianaceae ) Gentiana algida Pall. ; (Leguminosae) Hedysarum pseudastragalus Ulbrich (Z.-Y. Miao: 16.viii.2014, in the Tanggula mountains 5220 m, Xizang, China, Fig. 70 ).

Behaviour. No records.

Figures

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 69 ‒ 70. Photos of (69) a worker of B. superbus (MD # 4123) from (left) the dorsal and (right) the left lateral aspect (scale bar 10 mm), from the sample site (70) in the Tanggula mountains, Xizang, China (16. viii. 2014, 32.86142 ° N 91.91739 ° E, GPS elevation ca 5220 m). Photos by (69) NHM digital imaging unit and (70) Z. - Y. Miao.

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.

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.