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Extracted from: Milliron H.E., (1973). A Monograph of the Western Hemisphere Bumblebees (Hymenoptera: Apidae; Bombinae). The Entomological Society of Canada, No. 89.
Description. Queen. Length, 21.0 mm; width at wing bases, 9.0 mm; abdomen, 11.0 mm, width across T2, 9.5 mm; front wing length, 16.0 mm, width, 5.5 mm. Head: Frontal out line (excluding mouthparts) rounded trapezoidal, about as high as wide, vertical region nearly flat except slightly concave and smooth anteriad of lateral ocelli, ocular half of ocellocular area irregularly weakly punctured; outline of compound eye slightly broader below than above, its inner margin nearly straight, 3 times higher than wide; ocelli of medium size, situated in a nearly straight line just below supraorbital line, interocellar line slightly greater than ocellocular line; clypeus as wide as high, evenly convex above, covered with irregular well-separated punctures; labrum coarsely punctate, without prominent tubercles, 2i times wider than thick, with strong sparse pubescence; malar space about as long as distance between (and including) mandibular articulations, weakly convex and microscopically punctate with fine pubescence posteriorly; flagellum slightly more than twice the length of scape, FI li times longer than distal width, distinctly shorter than F2 and F3 combined, F2 about li times longer than wide. Legs: Mesobasitarsite elongate rectangular, distally obscurely emarginate, the distoposterior angle acute (but not spinate) and extended slightly beyond rounded arcuate distoanterior angle, outer surface shallowly concave longitudinally; outer hind tibial surface mid-longitudinally convex, alutaceous throughout; metabasitarsite slightly less than twice as long as greatest width, the posterior margin arcuate at basal one-fourth, beyond to subtruncate distal end nearly straight, basally slightly wider than distally, its outer surface shallowly concave and covered with recum bent pubescence, posterior fringe arcuate and long over proximal two-thirds (longest hairs equal to widest dimension of segment) but short on distal one-third, subacute distoposterior angle only slightly extended beyond arcuate distoanterior angle. Pubescence: Rather long and loose throughout; corbicular fringe long, loose, the most prominent considerably longer than greatest corbicular width; metabasitarsal posterior fringe long and arcuate on proximal two-thirds, beyond short and sparse. Color: Head black with some pubescence at tips tinged with ochraceous yellow. Thorax above pale ochraceous yellow except for rather broad ihdefinitely defined black interalar band, the mesopleuron predominantly sienneous yellow with black inter mixed, pleura otherwise and legs black. Abdominal Tl-2 pale ochraceous yellow, T3 with burnt sienna and black intermixed, T4 mostly black on basal half but predominantly burnt sienna distally, T5-6 largely burnt sienna with some black intermixed, venter almost entirely black except some hairs pale tipped. Wings lightly and uniformly infuscate.
Worker. Length, 14.0 mm; abdomen, 7.0 mm, width across T2, 6.5 mm; front wing length, 7.0 mm, width, 4.0 mm. Structural features relatively similar to those of the queen, except flagellum less than twice length of scape, FI being about 1£ times longer than distal width, much longer than quadrate F2, definitely shorter than F2 and F3 combined. Pubescence, color, and infumation of wings much as in the queen.
Male. Length, 16.0 mm; abdomen, 8.0 mm, width across T2, 6.5 mm; width at wing bases, 6.0 mm; front wing length, 14.0 (±) mm, width, 4.5 (±) mm. Head: Frontal outline rather narrowly rounded trapezoidal (excluding mouthparts), about as wide as high; compound eye twice as high as broad, more broadly arcuate below than above; ocelli situated as weak arc slightly below supraorbital line, nearly equidistant apart, interocellar line about equal to ocello- cular line, vertex behind ocelli finely irregularly punctate, the ocellar half of ocellocular area smooth and polished, ocular half with coarser weak sculpture; labrum broad dorsoventrally, about 2 times wider than high, its ventral margin truncate except for evenly rounded lateral corners, its surface nearly flat and irregularly weakly punctate except for diminutive smooth callosities distolaterally, devoid of noticeable pubescence except rather strong hairs along ventral area; flagellum nearly twice as long as scape, FI much longer than F2 and distinctly shorter than rectangular F3; malar space mostly convex and polished except posteriorly, about 1£ times longer than distance between (and including mandibular) articulations. Legs: Mesobasitarsite elongate rectangular, less than 3 times longer than widest dimension, the subarcuately rounded disto posterior angle slightly in recess of arcuate distoanterior angle, outer surface mid-longitudinally weakly concave and covered with fine, long and short reclined pubescence; metabasitarsite rectangular, about 2i times longer than greatest dimension, the outer surface mid-longitudinally evenly concave and covered with short and long recumbent pubescence, distal angles similar to those of the mesobasitarsite, the posterior margin weakly arcuate basally to nearly straight distally, posterior fringe long (longest more than greatest width of segment) almost throughout. Pubescence: Longer, looser and more uneven throughout than in the female. Genitalia, seventh and eighth sterna (PI. X II). Color: Head black except vertex mostly pale yellow, black hairs on clypeus with yellowish tinge. Thorax entirely drab yellow (except blackish mesopleuron) with intermixture of black hairs over interalar area (no discrete interalar black band); legs mostly with some intermixture of black but predominantly drab yellow, including fringes; abdominal Tl-2 tawny (to light) yellow, T3-4 mostly black with conspicuous intermixture of burnt sienna posteriorly and postlaterally, T5-7 mostly with drab burnt (yellowish) sienna. Wings lightly infumated, more so than those of the queen and worker.
Comments. Morphologically this species varies in several respects. Most noticeable is the length of the malar space, especially in the queens; this feature some times approximates that in balteatus (cf.) and also the shortest mandibular space of kirbyellus (cf.) but attention to other structures such as the relative comparative lengths of the flagellar segments, punctation on the clypeus, comparative length of and posterior arcuation of the metabasitarsite will serve to distinguish this species from close relatives throughout its range. There is no problem in separating the males on the basis of structure from any of the related species. Chromatically, polaris is very variable with respect to the thorax and abdomen in queens and workers, especially so in the males. The lightest queens are pallid to pale ochraceous yellow on the thoracic dorsum with rather wide definitely defined interalar black band, the
abdomen with Tl~2 almost entirely ochraceous (or lighter) yellow, T3 predomin antly ochraceous yellow intermixed with some black basally and basolaterally, T4-6 covered with rufescent tawny yellow except T6 ordinarily with short black hairs medially. Males often have the body dorsally almost entirely yellowish with only slight rufescent tinge to pubescence on the distal abdominal terga, though usually these terga in all castes are predominantly covered with rufescent yellow or fer ruginous pile. The chromatic pattern of paler polaris often closely parallels that of kirbyellus, balteatus, and strenuus\ and the darker specimens ( $ , $ , $ ), including melanics, by gross examination are easily confounded with any of the other four northern species. Often the thoracic dorsum of queens, workers, and males is pre dominantly black without any well-defined interalar band, and the abdominal dorsum might have pale conspicuous pubescence only on the basal and distal terga. Melanie specimens of workers and males before me, collected in the Northwest Territories
(Canada), cannot in any way be differentiated from Bombus arcticus v. alpiniformis described by Richards (1927h: 13), and later elevated to “specific rank” by Pittioni (1938h: 254) and by Elfving (1960a: 7, figs. 9, 10, 16, 17, key p. 33). Comparable melanics (all castes) of all high and low arctic species of the Western Hemisphere species have been seen by me.
Often small workers, approximating 10-12.0 mm appear in the semblance of frigidus (Sm.), but such specimens can be distinguished as this species by the com parative lengths of the flagellar segments, posterior shape of the metabasitarsite, punctation on the clypeus, etc
Extracted from: Laverty T.M., & Harder L.D., (1988). The Bumble Bees of Eastern Canada. Can. Ent. 120: 965-987.
Description. Body size of all castes medium. Head slightly elongate; malar space about
as long as broad in female, about 1.25 times longer than broad in male. Tongue length short. Colour as in Figure 18. In some females, T3 yellow or with intermixed black and yellow hairs; y,ellow on T4 and T5 reddish-orange in some specimens. In some males, interalar band with intermixed yellow and black pile; T4 reddish-orange or not. Melanic forms occur on the Arctic Islands; pile mostly black with light hairs intermixed and T5-T7 with yellow-orange hairs.
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