Bombus tibeticus Williams & Altanchimeg & Byvaltsev & Jonghe & Jaffar & Japoshvili & Kahono & Liang & Mei & Monfared & Nidup & Raina & Ren & Thanoosing & Zhao & Orr 2020, sp. nov.

Bombus tibeticus Williams sp. nov.

urn:lsid:zoobank.org:act: 200860 A6-7E80-47AA-A5B0-BE9C95AE977A

Figs 16, 151–152, 200, 207, 212

Bombus keriensis (part) – Reinig 1935: 341. — Williams 1998: 134 (non Morawitz, 1887: 199). This species was treated (implicitly from specimens from its unique known range) as a part of B. keriensis s. lat. (the keriensis -complex) by Reinig (1935) and by Williams (1998).

Our PTP analysis (Fig. 10) of coalescents in the COI gene within the keriensis -complex supports six species including B. tibeticus sp. nov., corroborated by differences in morphology and by the absence of a positive divergence-with-distance relationship among them (Fig. 20) (see Divergence and geographical distance, page 12). This is the first time that B. tibeticus sp. nov. is recognised as a separate species.

Bombus tibeticus sp. nov. co-occurs locally with the closely similar B. qilianensis sp. nov. in the eastern Kunlun mountains of the QTP (PW pers. obs.).

Diagnosis

Within the keriensis -group: female with the clypeus in its central area with scattered large, medium, and small punctures; hair in the black band between the wing bases without yellow hairs intermixed; hair on the side of the thorax with the yellow extending half of the distance from the wing base to the mid leg base; T1–2 yellow, T3 entirely black, T4–6 orange-red.

Male with hair on the head black except for yellow in a tuft on the face ventral to the antennal base and on the vertex; thoracic dorsum with the black band between the wing bases without yellow hairs intermixed; side of the thorax yellow anterior to the wing base; legs with the long hairs intermixed black and pale; T1–2 yellow, T3 entirely black, T4–7 orange-red; eye unenlarged relative to female eye.

Etymology

Named after the region where it occurs, Tibet, but with an unusual latinisation in order to avoid homonymy with the more usual forms Bombus tibetanus (Morawitz, 1887), Bombus tibethinus Gribodo, 1892, and Bombus tibetensis S.-F. Wang, 1982, as well as with the form Bombus xizangensis S.-F. Wang, 1979. Of these, only B. (Psithyrus) tibetanus (Morawitz) is currently the accepted valid name of a bumblebee species, but in the distantly-related subgenus of parasitic bumblebees, Psithyrus Lepeletier, 1832. The form tibeticus has been used previously for another bee species, Colletes tibeticus Kuhlmann (2002). Although there are other similar published names, this name is a particularly good description of this species, which is widespread on the southern and eastern QTP. The species epithet is to be treated as a simple adjective.

Material examined

Holotype designation

CHINA • ♀ (worker) pinned (the right front leg is missing); four labels: (1) white printed in black “ CHINA: Qinghai / Kunlun Shan/Alpine edge 3973m 19 / 35.80313N, 94.34232E / 13.viii.2013 PH Williams ”; (2) green printed in black “ Melanobombus / ML# 228. det. PHW”; (3) green printed in black “BOLD# BBWP/PHW /CCDB-1555-B09”; (4) red printed in black “ HOLOTYPE ♀ (w)/ Bombus / tibeticus / Williams, 2019 /det. PH Williams 2019 ”; IOZ (Fig. 207).

Material sequenced (16 specimens)

CHINA – Qinghai Province • 1 ♂; Xiangpishan; 36.7589° N, 99.6041° E; 30 Aug. 2010; P. Williams leg.; BOLD seq: 1555B05; PW: ML224 • 1 ♂; same collection data as for preceding; BOLD seq: 1555B06; PW: ML225 • 1 ♂; same collection data as for preceding; BOLD seq: 1555E04; PW: ML252 • 1 ♂; same collection data as for preceding; BOLD seq: 6880A12; PW: ML484 • 1 ♀ (worker); Nanshan pass; 36.7628° N, 99.6071° E; 17 Aug. 2013; P. Williams leg.; BOLD seq: 1555B10; PW: ML229 • 1 ♀ (worker); Burhan Budai Shan; 36.0556° N, 98.1170° E; 16 Aug. 2013; P. Williams leg.; BOLD seq: 1555B11; PW: ML230 • 1 ♀ (worker); Kunlun Shan; 35.6920° N, 94.052° E; 13 Aug. 2013; P. Williams leg.; BOLD seq: 6877F09; PW: ML402 • 1 ♂; Nuogancha; 37.0982° N, 98.8706° E; 31 Aug. 2010; P. Williams leg.; BOLD seq: 6877F11; PW: ML404 • 1 ♂; same collection data as for preceding; BOLD seq: 6880B03; PW: ML487 • 1 ♀ (worker); same collection data as for preceding; BOLD seq: 6876H07; PW: ML23. – Xizang Province • 1 ♀ (queen); Sugela [Shogu La]; 29.9154° N, 90.1421° E; 24 Jun. 1999; K. Huber leg.; BOLD seq: 1552A09; OLML: ML202 • 1 ♀ (worker); Milashan; 29.85301° N, 92.33378° E; 27 Jul. 2018; Z. Ren leg.; KIB seq: MLSM101022; KIB: ML564 • 1 ♀ (worker); Yelashan; 30.16394° N, 97.2860° E; 22 Jul. 2018; Z. Ren leg.; KIB seq: YLSH101083; KIB: ML565 • 1 ♀ (worker); Xizang; Z. Ren leg.; KIB seq: CLiBE035; KIB: ML575 • 1 ♀ (worker); Yelashan; 30.1639° N, 97.2860° E; 22 Jul. 2018; Z. Ren leg.; KIB: YLSH101083; KIB: ML576 • 1 ♀ (worker); Anjiulashan; 29.9229° N, 96.67203° E; 23 Jul. 2018; Z. Ren leg.; KIB seq: AJLSM101016; KIB: ML577.

Description

Female (holotype worker)

Habitus illustrated in Fig. 207. Body size medium (body length of queens 17–20 mm, workers 10–14 mm), hair (pubescence) moderately short and even, wings clear. Mandible with the distal notch anterior to the posterior tooth (incisura) very shallow and hardly marked. Oculo-malar area (‘cheek’ sensu Williams et al. 2014; not the gena) of medium length, 1.05 × as long as (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) the breadth of the mandible at its base (breadth between and including the mandibular condyles). Clypeus weakly swollen, its raised area nearly flat, the central area with scattered large, medium and small punctures, few punctures medially and ventrally adjacent to the labrum. 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 half by a broad band of mostly large punctures, many spaced by more than their own widths, the smaller punctures between the larger punctures more abundant laterally near the eye margin. 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 densely covered with short branched decumbent and overlapping hairs with golden reflections; T6 posteriorly truncate and very shallowly divided medially. Colour pattern of the hair of the body predominantly black. Head entirely black except for orange hairs anteriorly on the labrum. Thoracic dorsum with broad anterior and posterior yellow bands of nearly equal breadth, about equal in breadth to the black band between the wing bases and without black hairs intermixed, the black band between the wing bases without yellow hairs intermixed; side of the thorax (mesepisternum) predominantly black, in its dorsal half yellow. T1–2 yellow without any black hairs; T3 entirely black; T4–6 entirely orange-red.

Male (ML225)

Body size medium (body length 12–15 mm), hair (pubescence) moderately short and even, wings clear. Colour pattern of the hair of the body predominantly black. Head black except for yellow in a tuft on the face ventral to the antennal base, on the vertex, and posteriorly around the base of the proboscis. Thoracic dorsum with broad anterior and posterior yellow bands of nearly equal breadth and without black hairs intermixed, the black band between the wing bases without yellow hairs intermixed; side of the thorax (mesepisternum) yellow anterior to the wing base; legs with the long hairs intermixed black and pale. T1–2 yellow without any black hairs; T3 entirely black; T4–7 entirely orange-red. Genitalia (Fig. 200) with the gonostylus shorter than broad, its inner basal projection reduced to a short stub; volsella with the inner distal corner broadly produced but without a narrow hook.

Global distribution

(Qinghai-Tibetan-Plateau species) East Asia: CHINA: Xizang, Qinghai. (IAR, IOZ, NHMUK, OLML, PW.) This species is often common relative to other bumblebees (Fig. 212).

This is one of the highest recorded bumblebees in the world, at an elevation of ca 5640 m a.s.l. (Williams 2018: along with B. tanguticus). Specimens in the NHMUK collection labelled “ Sikkim ” are actually from Xizang (“Kampa Dzong” = Gampa Dzong, 28.271° N, 88.513°E).

Behaviour

Food-plant generalists (PW, ZR unpublished records). The male mate-searching behaviour is expected to resemble the patrolling behaviour of B. keriensis s. str.