Bombus miniatus Bingham, 1897

Williams, Paul H., Altanchimeg, Dorjsuren, Byvaltsev, Alexandr, Jonghe, Roland De, Jaffar, Saleem, Japoshvili, George, Kahono, Sih, Liang, Huan, Mei, Maurizio, Monfared, Alireza, Nidup, Tshering, Raina, Rifat, Ren, Zongxin, Thanoosing, Chawatat, Zhao, Yanhui & Orr, Michael C., 2020, Widespread polytypic species or complexes of local species? Revising bumblebees of the subgenus Melanobombus world-wide (Hymenoptera, Apidae, Bombus), European Journal of Taxonomy 719, pp. 1-120 : 52-54

Bombus miniatus Bingham, 1897

Figs 13 , 50–54 , 185

Bombus flavothoracicus Bingham, 1897: 552 (non Hoffer, 1889: 49 = B. campestris (Panzer)) . Bombus miniatus Bingham, 1897: 553 .

Bombus stenothorax S.-F. Wang, 1982: 439.

Bombus pyrosoma (part) – Williams 1991: 101 (non Morawitz, 1890: 349).

Bombus miniatus s. lat. was treated as a widespread Himalayan species by Williams (1998), to include the taxon eurythorax . Here, B. miniatus s. str. is recognised as a narrowly distributed east Himalayan species, separate from the west Himalayan species B. eurythorax , because of their unique and strongly divergent species coalescents in the COI gene ( Fig. 10 ), corroborated by differences in morphology.

The morphological differences are subtle, but do appear to support the two as separate species within a morphologically more distinctive complex of miniatus s. str. + eurythorax .

Our PTP analysis ( Fig. 10 ) supports relatively strongly two coalescents in the COI gene for the west Himalayan B. eurythorax , and the east Himalayan B. miniatus s. str. (sequenced here only from Bhutan). The two coalescent groups differ in COI barcode sequences for at least 21 diagnostic nucleotide positions (3.1% of the barcode region, although some sequences are incomplete). These nucleotide differences are all synonymous, making no difference to the amino acid sequences at translation.

From morphology, B. miniatus s. str. has a paler colour pattern than B. eurythorax for the females (larger workers and queens). The pale hair is also more extensively intermixed in the dark band between the wing bases for B. miniatus s. str. All of the larger females (queens and workers) of B. miniatus s. str. have the yellow bands on the thorax and T1 grey or cream-white (see Streinzer et al. 2019: their supplementary fig. 2B) rather than yellow or brown as for B. eurythorax . Bombus miniatus s. str. queens have T2 often with few pale hairs anteriorly. Males from Lungtenphu in Bhutan and from Sikkim (sequences unavailable) show no obvious morphological differences from B. eurythorax other than less yellow hair on T3–7.

Available samples of B. miniatus s. str. are small and mostly old, so the status of the two candidate species remains uncertain. Current restrictions on collecting and sequencing in the areas where the two candidate species are most likely to occur in proximity ( Fig. 13 ) make clarifying their status difficult. However, more evidence is needed to increase confidence in any interpretation of the status of the candidate species miniatus s. str. and eurythorax and it remains possible with more sampling from the Himalaya that the two taxa could still prove to be parts of a single broader species, B. miniatus s. lat. Speciation between B. eurythorax and B. miniatus s. str. may have arisen through vicariance between populations of the western and eastern Himalaya caused by a period of altered climate (cf. B. prshewalskyi / B. rufofasciatus ).

Females of B. miniatus s. str. show pronounced size-dependent dimorphism in the colour pattern of the hair: large queens have T2 black and T4 white (taxon flavothoracicus ); whereas workers (which are smaller) have T2 brown-yellow and T4 red. Males have the thoracic dorsum and T1–2 extensively yellow and T3–5 extensively orange-red (taxon miniatus s. str.). Consequently, the queens and males were first described as two separate species by Bingham (1897).

Diagnosis

Females

Queens large body length 21–28 mm, workers 11–16 mm. Can be distinguished by the combination of the hair of the thoracic dorsum with some grey or cream-white with T5 at least posteriorly white (cf. B. eurythorax , B. rufofasciatus , B. friseanus , B. keriensis , B. richardsiellus ).

Males

Body length 17 mm. Can be distinguished reliably at present only by their COI sequence, but hair of T3–7 bright orange without posterior yellow fringes (cf. B. eurythorax ). As well as the holotype male from Sikkim, there is another unsequenced male (ML513) from Lungtenphu in Bhutan presumed to be of this species, although this cannot be confirmed without a barcode sequence. Genitalia ( Fig. 185 ) with the gonostylus much reduced, less than a quarter as long on its outer side as broad, with the distal edge concave and the inner distal process broadly square-ended or weakly bidentate, the inner basal process acutely produced (cf. other rufofasciatus -group species except B. eurythorax ); volsella with the inner distal corner produced as a narrow curved hook ( cf. rufipes -group, B. simillimus , lapidarius -group, sichelii -group, keriensis -group) eye unenlarged relative to female eye.

Material examined

Holotype

INDIA • ♂, holotype of Bombus miniatus Bingham, 1897 by original designation; Sikkim, Lintu ; May 1894; C. Bingham leg.; NHMUK (examined PW).

Material sequenced (6 specimens)

BHUTAN • 1 ♀ (worker); Thimphu, Lungtenphu ; 27.4574° N, 89.6655° E; Jul. 1995; H. Feijen leg.; BOLD seq: 6880H04; RMNH: ML508 • 1 ♀ (worker); same collection data as for preceding; 7 Jun. 1996; BOLD seq: 6880H05; RMNH ML509 • 1 ♀ (worker); Paro, Chele-La; 27.3699° N, 89.3466° E; 11 Sep. 1994; G. Schulten leg.; BOLD seq: 6880H08; RMNH: ML512 • 1 ♀ (queen); Lhuntse, Sengor ; 27.3893° N, 90.9822° E; 10 Jun. 2017; W. Klein leg.; NBC seq: 10115; RMNH: ML567 • 1 ♀ (queen); same collection data as for preceding; NBC seq: 10113; RMNH: ML568 • 1 ♀ (queen); Thimphu, Phajoding Gompa ; 27.479° N, 89.595° E; 25 Apr. 2018; W. Klein leg.; RMNH seq: 1092464; RMNH: ML569 .

Global distribution

(East Himalayan mountain species) East Asia: CHINA: Xizang (southern margin only). – Himalaya: INDIA: Sikkim, Arunachal Pradesh; BHUTAN. (IOZ, NHMUK, RMNH.) The species is narrowly restricted to the eastern Himalaya but appears to be abundant locally.

Behaviour

Food-plant choice expected to be generalist but no records. The male mate-searching behaviour is expected to resemble the patrolling of B. eurythorax .

Figures

Figs 12‒13. Maps of sequenced samples. 12. The rufipes-group and festivus-group. 13. The rufofasciatus- group as recognised as species from the UHF-PTP analysis in Fig. 10. Keys to the coloured symbols are shown on the left (in some cases symbols on the map for one species may overlie symbols for another). Maps projected onto a sphere in ArcGIS using World_Shaded_Relief basemap © 2014 ESRI and showing boundaries between countries as recognised by the UN.

Figs 25–63. Simplified diagrams for the colour patterns of the hair on the dorsum for the species from the integrative analysis. 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, with olive indicating a mixture of black and yellow hair, and grey indicating a mixture of black and white hair. The rufipes-group. 25. Queen, China-Taiwan. 26. Queen, China-Guangdong. 27. Worker, China-Sichuan. 28. Worker, Thailand. 29. Queen, Nepal. 30. Male, China-Sichuan. 31. Male, China-Sichuan. 32. Male, Thailand. 33. Male, Nepal. 34. Male, Nepal. 35. Queen, Indonesia-Sumatra. 36. Queen, Indonesia-Java. 37. Male, Indonesia-Java. The festivus-group. 38. Queen, Nepal. 39. Queen, China-Sichuan. 40. Worker, China- Sichuan. 41. Worker, China-Xizang. 42. Worker, China-Yunnan. 43. Male, Nepal. 44. Male, China- Yunnan. 45. Male, China-Yunnan. The rufofasciatus-group. 46. Queen, India-Kashmir. 47. Worker, India-Kashmir. 48. Male, India-Kashmir. 49. Male, India-Kashmir. 50. Queen, India-Arunachal Pradesh. 51. Queen, Bhutan. 52. Worker, Bhutan. 53. Worker, Bhutan. 54. Male, Bhutan. 55. Queen, India-Kashmir. 56. Queen, India-Kashmir. 57. Worker, India-Kashmir. 58. Worker, India-Kashmir. 59. Worker, India- Kashmir. 60. Worker, Pakistan. 61. Male, India-Kashmir. 62. Male, India-Kashmir. 63. Male, Nepal.

Figs 181‒189. Morphology of the male genitalia for species of the subgenus Melanobombus von Dalla Torre, 1880 from the dorsal aspect, anterior at the bottom of the image, posterior at the top. 181. Bombus eximius Smith, 1852, China-Guangxi. 182. B. rufipes Lepeletier, 1835, Indonesia- Java. 183. B. festivus Smith, 1861, Nepal. 184. B. simillimus Smith, 1852, India-Himachal Pradesh. 185. B. miniatus Bingham, 1897, Bhutan. 186. B. eurythorax Wang, 1982 stat. rev., India-Kashmir. 187. B. prshewalskyi Morawitz, 1880 stat. rev., China-Sichuan. 188. B. rufofasciatus Smith, 1852, India- Kashmir. 189. B. richardsiellus (Tkalců, 1968), Burma (left volsella distal part missing). Scale bars = 1 mm.

Fig. 10. October 2019 (Fig. 8) Bayesian PTP analysis of MrBayes tree of unique COI barcodes (UHF- PTP). Symbols as in Fig. 9.