Bombus convexus Wang

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 : 33-34

3. Bombus convexus Wang

( Figs 2 , 26 , 39, 41 , 58 )

< Bombus > lugubris Morawitz 1880:339 (not of Kriechbaumer 1870:159, = B. barbutellus (Kirby) s. l.), type-locality citation ‘Gan-su’. Holotype worker by monotypy ZISP examined, ( Cyrillic ) ‘[Gansu]’ (but probably actually Qinghai, China). Synonymised with Bombus convexus Wang by Williams (1991). Note 1.

Bombus lugubris Morawitz; Morawitz 1881 :243; Wu 1941:281.

Mendacibombus lugubris (Morawitz) ; Skorikov 1923:149; Skorikov, 1931:213.

Bombus (Mendacibombus) lugubris Morawitz ; Bischoff 1936:17; Panfilov 1957:235; Tkalců 1961:369.

Bombus (Mendacibombus) convexus Wang, 1979:190 , type-locality citation (Chinese) ‘[Xizang: Markam]’. Holotype queen by original designation IZB examined, ( Chinese ) ‘[Markam]’ (Xizang, China).

Bombus (Mendacibombus) convexus Wang; S.-F. Wang 1982 :429; Yao & Wang 2005:890; P.H. Williams 1991:42; S.- F. Wang 1992:1424; P.H. Williams 1998:100; P.H. Williams 2004:no. 26; Cameron et al. 2007:165; P.H. Williams et al. 2009:130; An et al. 2011:5; An et al. 2014.

Note 1 ( lugubris ). The original publication specifies that there was only one type (worker) specimen of the taxon lugubris Morawitz , so the worker in the ZISP collection is regarded as the holotype by monotypy ( ICZN, 1999: Article 73.1.2).

Etymology. The species is named from the Latin convexus for ‘rounded’, a reference to a pronounced convexity or rounded posterior projection of the median posterior edge of metasomal T 2 in the original description.

Taxonomy and variation. This species shows effectively 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 specimens have a white-banded and none has a yellow-banded colour pattern. The form of the female median posterior edge of T2 (although slightly variable) and of the male genitalia are diagnostic.

Diagnostic description. Wings nearly clear. Hair long, uneven and sparse. Female hair colour pattern: generally black, but with white hair intermixed especially as short hairs on the face, intermixed in a transverse band anteriorly on the thoracic dorsum and extending laterally and ventrally without black hairs to the midleg base, in a lateral patch posteriorly on the thoracic dorsum (lateral patch on the scutellum, metanotum, and propodeum, so that the thoracic dorsum between the wing bases has the hair entirely black), on T1 and anteriorly on T2, and intermixed on T4‒6 (cf. all other Mendacibombus species). Hindleg tibia with the corbicular fringes black, often with a few hairs with orange or white tips. Female morphology: labrum with the basal depression narrow, the transverse ridge moderately broad and high, medially not subsiding or interrupted and in the median third with scattered large punctures, lateral tubercles with a few scattered small punctures. T2 usually with a posteriorlydirected convexity of its median posterior edge, affecting a quarter of its breadth, especially pronounced in queens, for which there may be edge concavities and even slight pre-marginal depressions lateral to the convexity. Male morphology: beard of the mandible long, dense and black, but the short hairs and a few of the long hairs brown; T2 and sometimes T3 with posteriorly-directed convexities of their median posterior edge, affecting a quarter or less of their breadth. Genitalia ( Fig. 26 ) 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 0.3× the remaining distal length of the volsella; volsella distally sharply acute (pointed) and curled back dorsally and anteriorly. Gonostylus length 2× its greatest breadth. Penis-valve head length 0.25× the length of the penis valve distal to the broadest point of the spatha.

Material examined. 6 queens 296 workers 51 males, from China ( Fig. 58 : AMNH, IAR, IZB, NHM, PW, SC, USNM, YT, ZISP, ZX), with 6 specimens sequenced (interpretable sequences listed in Figs. 11–13 ).

Habitat and distribution. Flower-rich alpine and subalpine grassland, at elevations 2196‒(3449)‒ 4500 m a.s.l.. A species of the east Qinghai-Tibetan plateau, in the east Himalayan, Hengduan, and Qinghai-Gansu mountains, including the Min Shan and Qilian Shan. Compared to B. waltoni , distributions of the two species overlap broadly, but B. convexus extends less far to the north and west and tends to occur at lower elevation (and the two species rarely occur together at a site). Bombus convexus replaces the western B. avinoviellus in the lower alpine zone and upper forest wet meadows of the eastern Himalaya, where it appears to be rare. Regional distribution maps are available for Sichuan (P.H. Williams et al. 2009) and Gansu (An et al. 2011; An et al. 2014).

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

Behaviour. Mate-searching males perch on bare patches of ground and pursue other bees that fly past before the males return to the same perch (PW: Fig. 2 , 29 .viii. 2009, 3339 m Diebu , Gansu, China).

Figures

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.

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.