Bombus polaris Curtis

Williams, Paul H., Berezin, Mikhail V., Cannings, Sydney G., Cederberg, Björn, Ødegaard, Frode, Rasmussen, Claus, Richardson, Leif L., Rykken, Jessica, Sheffield, Cory S., Thanoosing, Chawatat & Byvaltsev, Alexandr M., 2019, The arctic and alpine bumblebees of the subgenus Alpinobombus revised from integrative assessment of species’ gene coalescents and morphology (Hymenoptera, Apidae, Bombus), Zootaxa 4625 (1), pp. 1-68 : 28-31

3. Bombus polaris Curtis

( Figs. 3 , 39‒58 , 131 , 140, 142 , 147 )

< Bombus > Arcticus Kirby in Sabine 1824 : ccxvi (not of Quensel 1802:253, = B. hyperboreus Schönherr ), type-locality citation ‘Melville Island and wherever the expedition landed within the arctic circle’. Lectotype queen (#285) by present designation, NHMUK examined PW, ‘Melvilles I.’ (Melville Island, Nunavut, Canada). Notes 1, 2. Synonymised with Megabombus polaris (Curtis) by Milliron (1973:98); confirmed from lectotypes here.

< Bombus > Polaris Curtis 1835 :lxiii, type-locality citation ‘ Arctic’ (from the dates, account, and map in Ross: probably the Boothia Peninsula isthmus, Nunavut, Canada). Lectotype queen (#3856) by present designation, NHMUK examined PW, no locality label. Notes 3, 4.

[ BOMBUS DERHAMELLUS Kirby; Kirby 1837:273, misidentification ( Frison 1923:317).]

BOMBUS GROENLANDICUS [ groenlandicus ] Smith 1854:393, type-locality citation ‘Greenland’. Holotype queen (#4740) by monotypy, NHMUK examined PW, ‘W. Greenl’ ( Greenland, label added by Smith?). Synonymised with Bombus arcticus Kirby by Franklin (1913:302). Note 5.

Bombus Kincaidii Cockerell 1898:324 , type-locality citation ‘Pribilof Islands St Paul’ (Alaska, USA). Lectotype queen (#4407) by present designation, NMNH examined PW, ‘Pribilof Is / St Paul’ (Alaska, USA). Note 6. Considered likely to be conspecific with Bombus polaris Curtis by Franklin 1913:296; synonymised with Megabombus polaris (Curtis) by Milliron (1973:99); confirmed from lectotypes here.

Bremus pleuralis var. clarus Frison 1926:139 , type-locality citation ‘ Tam Cod Hill , Alaska’ ( USA). Holotype male (#5010) by original designation, INHS examined PW. Synonymisation with Bombus polaris Curtis suggested by Williams et al. (2016:2), confirmed here.

[< Alpinibombus arcticus > mod. natvigioides Skorikov 1937:56, infrasubspecific.]

[Alpinibombus kincaidi (Cockerell); Skorikov 1937:58, incorrect subsequent spelling.]

Note 1 ( arcticus ). That more than one syntype was seen by Kirby is indicated by the description of both sexes and by a broad region of type localities.

The NHMUK collection contains a queen (#3857) that has been regarded as the primary type of this taxon (e.g. Milliron 1960:89; Løken 1973:101; see also Richards 1931:11). However, none of these authors explicitly recognized the description of a syntype series in the original William Kirby publication and then selected a single individual as the lectotype, so these uses of the term ‘type’ do not constitute a valid lectotype designation ( ICZN 1999: Article 74.5). This NHMUK specimen carries the labels: (1) white, ‘ B. arcticus ’ in handwriting that appears to form much more rounded letters than did Kirby (see below); (2) white round, handwritten label ‘40 / 4 – 2 / 628’; (3) white, handwritten ‘ Bombus / arcticus / TYPE Kirby.’; (4) red-edged, printed ‘Type’; (5) white, printed ‘B.M. TYPE / HYM. / 17B.1043.’; (6) red-edged, printed ‘Holo- / type’; (7) green, printed ‘ Alpinobombus / AL# 3857. det. PHW’. The NHMUK accession number on the second label refers in the NHMUK accessions register to a purchase ‘Bought at Mr Children’s sale’ in 1840. This is presumably a reference to John Children, who became Keeper of Zoology at the British Museum, retiring in 1840. It is possible that Children may have acquired the specimen from Kirby through his association with the BM, so that this specimen could be a syntype. Milliron (1973:100) suggested that the specimen was labelled as type by Frederick Smith. However, this NHMUK specimen does not agree with the original Kirby description in that: (1) the hair of metasomal T4‒6 is not entirely black but has a lot of brownish grey hair; (2) it does not have ‘Some black hairs at the base of the last yellow segment of this part of the body’ (for this specimen the last yellow segment is metasomal T2); and (3) its body length (17 mm) is substantially shorter than the description of 11 lines (23 mm). While this specimen may be a syntype, at present its status remains uncertain.

In contrast, the NHMUK collection contains another female specimen (#285) that agrees more closely with the original description in having the hair of metasomal T4‒6 black. It agrees particularly closely in having ‘Some black hairs at the base of the last yellow segment of this part of the body’ (for this specimen, metasomal T3) and in its large body length, which matches the description of 11 lines (23 mm). This specimen has labels: (1) white, ‘ Bombus / arcticus K / Melvilles I. / Sabine ’ in handwriting closely similar to examples of Kirby’s handwriting in the NHMUK Kirby collection (Edward Sabine held the rank of Astronomer on HMS Hecla of William Parry’s expedition to seek the Northwest Passage and was the author of the sections in the account on mammals, birds, fish, and insects); (2) green, printed ‘ Alpinobombus / AL# 285. det. PHW’; (3) red, printed ‘ LECTOTYPE [female] / Bombus / arcticus / Kirby, 1824 / det. PH Williams 2014 ’; (4) white, printed ‘[female] Bombus / ( Alpinobombus ) / polaris / det. PH Williams 2014 ’. This specimen is regarded here as one of Kirby’s syntypes because it matches the original description in individual detail and carries a Melville Island label in what appears to be early nineteenth century handwriting, closely similar to that of Kirby, along with the name of Sabine, who was part of the Parry expedition. The specimen has been damaged by physical compression, by Anthrenus attack, has droplets of glue especially on its head, and is now mounted on a strip of board. It is designated here as lectotype in order to reduce uncertainty in the identity and application of the name, which is interpreted as remaining applied to the same species.

Note 2 ( arcticus ). The glossary of the ICZN (1999:111) states that nomina oblita (e.g. Bombus arcticus (Quensel)) remain available names. Therefore Bombus arcticus (Quensel) remains a senior homonym for Bombus arcticus Kirby.

Note 3 ( polaris ). Only a pair of male and female syntypes were described by John Curtis. The NHMUK collection contains a queen that has been regarded as the primary type of this taxon (e.g. Milliron 1960:95; Løken 1973:101). It agrees with the original description (with extensive orange-yellow hair on metasomal T3‒5) and car- ries the labels: (1) white, handwritten ‘ Bombus / polaris . Curt. Type. from Curtis. ’; (2) white, part handwritten ‘type F. Sm. Coll. / 79.22’; (3) printed white with a red border ‘Type’; (4) white, printed ‘B.M. TYPE / HYM. / 17.B.1054’; (5) printed white with a red border ‘Holo / type’; (6) green, printed ‘ Alpinobombus / AL# 3856. det. PHW’; (7) red, printed ‘ LECTOTYPE [female] / Bombus / polaris / Curtis, 1835 / det. PH Williams 2014 ’; (8) white, printed ‘[female] Bombus / ( Alpinobombus ) / polaris / det. PH Williams 2014 ’. The specimen lacks only the antennae. It is designated here as lectotype in order to reduce uncertainty in the identity and application of the name.

Note 4 ( polaris ). Because Bombus arcticus Kirby is a junior homonym (see note 2 above), it cannot be used as the valid name for this species ( ICZN 1999: Article 52.2), which must take the next oldest available name, Bombus polaris Curtis.

Note 5 ( groenlandicus ). Smith’s description of Bombus groenlandicus states: ‘Abdomen, the two basal segments covered with long yellow pubescence, the apical ones with black’. The specimen in the NHMUK collection labelled as the holotype (#4740) has dull orange hair intermixed posteriorly on metasomal tergum 4 and more extensively on tergum 5, although the orange is less obvious than on some specimens. This discrepancy with Smith’s description is not pursued here because it is unlikely to affect the valid name of the species.

Note 6 (kincaidii). Cockerell listed 4 queens, 1 worker, and 2 males as syntypes in the original description, without specifying a holotype. The NMNH collection contains a queen (#4407) that has been regarded as the primary type of this taxon (e.g. Franklin 1913:295). However, Franklin did not explicitly select a single individual as the lectotype, so this use of the term ‘type’ does not constitute a valid lectotype designation ( ICZN 1999: Article 74.5). The NMNH queen that has been regarded as the primary type of this taxon ( Franklin 1913:295) agrees with the original description (with extensive yellow hair on metasomal T1‒3, black hair on T4‒6) and carries the labels: (1) white, handwritten in black ink ‘Pribilof Is / St Paul’; (2) white, handwritten in pencil ‘ 8 1 / 97 ’; (3) white, handwritten in pencil ‘Lathyrus’; (4) white, handwritten in black ink ‘ Bombus / Kincaidii / Ckll TYPE.’; (5) red, part printed ‘Type / No. 5179 / U.S. N.M.’; (6) yellow, printed ‘USNM ENT / 00534360 / [barcode]’; (7) green, printed ‘ Alpinobombus / AL# 4407. det. PHW’; (8) red, printed ‘ LECTOTYPE [female] / Bombus / kincaidii / Cockerell, 1898 / det. PH Williams 2014 ’; (9) white, printed ‘[female] Bombus / ( Alpinobombus ) / polaris / det. PH Williams 2014 ’. The specimen lacks the right antennal flagellum and part of the right hind tarsus. It is designated here as lectotype in order to reduce uncertainty in the identity and application of the name.

Taxonomy and variation. Bombus polaris has long been considered to include B. pyrrhopygus but has recently been recognized as separate based on evidence of a species coalescent in the COI gene ( Williams et al. 2015; Fig. 9 ). Bombus polaris is vicariant with B. pyrrhopygus across the Bering Strait ( Figs. 22 , 39 ).

Variation in the colour pattern has been illustrated and analysed previously ( Williams et al. 2014; Williams et al. 2015). The ‘unbanded’ colour pattern without (or with much reduced) yellow bands on the thorax and T1‒2 ( Figs. 51, 58 ) is rare and known to us only from the Northwest Territories (Daring Lake: #19) and Nunavut (Churchill: #29). Individuals from the Bering Sea islands are especially pale ( Fig. 41 ). Otherwise the principal variation in this species is in whether T4‒5 are predominantly orange ( Figs. 40‒45, 51‒55, 57‒58 ) or predominantly black ( Figs. 46‒50, 56 ).

Individuals with both the banded and the unbanded colour patterns and both the ‘orange-tailed’ and ‘blacktailed’ colour patterns share some of the same alleles, although there may be some variation in the relative frequency of the two patterns with latitude ( Williams et al. 2015).

Material examined. 452 queens 232 workers 152 males (plus 54 individuals with sex/caste undetermined), from USA, Canada, and Greenland ( Fig. 39 : AMNH BBSL BP CNC CR EMEC INHS KM NHMUK MNHU NMNH PCYU PR PW RBCM ROM RSM SC SEMC UAM UCRC WRME YPM ZISP), with 53 specimens COI barcoded.

Habitat and distribution. Flower-rich arctic/alpine tundra in the New World including Greenland, north to Ellesmere Island and the north of Greenland, extending southwards into the subarctic region in the St Paul Islands and Aleutian Islands, and in the alpine zone of the Alaskan and Yukon mountains. Regional distribution maps ( Milliron 1973; Richards 1973; Laverty & Harder 1988; Williams et al. 2014).

Food plants. ( Richards 1931; Milliron & Oliver 1966; Milliron 1973; Richards 1973; Pape 1983; Williams et al. 2014)

Behaviour. ( Milliron & Oliver 1966; Richards 1973; Pape 1983)

Conservation status. This species has not yet been fully assessed for Red List threat status using IUCN criteria (2001). Hatfield et al. (2016d) have listed B. polaris as ‘Data deficient’.

Figures

FIGURE 9. Estimate of the metric gene tree for the 54 longest unique COI-barcode alleles of the subgenus Alpinobombus from MrBayes combined with the Bayesian Poisson-tree-process (PTP) solution with the highest support with spots showing the nodes with the strongest support as coalescents for candidate species (outgroup B. ignitus not shown). Values above the nodes are Bayesian posterior probabilities showing branch support for groups; values below the nodes are PTP Bayesian support values that all daughter alleles are parts of a single species (probabilities within candidate species are all ≤ 0.44). The scale bar is calibrated in substitutions per nucleotide site. Each unique allele is represented by one of the longest available sample sequences, labelled with: the sequence length in number of nucleotides, a taxon name or name describing an unpublished colour pattern, and then a code that consists of a specimen identifier (AL#n) from the project database and (after the hyphen) a sample identifier from BOLD or GenBank, followed with its geographic origin (for simplicity Greenland is included without Denmark).

FIGURES 1‒6. Lateral views of foraging females (queens) of species of the subgenus Alpinobombus (with photo credits): 1, B. alpinus, Norway (A. Staverløkk); 2, B. pyrrhopygus, Sweden (G. Holmström); 3, B. polaris, Canada (B. Heinrich); 4, B. balteatus, Sweden (G. Holmström); 5, B. kirbiellus, USA (D. Wilson); 6, B. hyperboreus, Sweden (L.-I. Larsson). Some images reversed.

FIGURES 39‒58. 39: Bombus polaris global distribution (as for Fig. 15). 40‒58 colour patterns (as for Figs. 16‒21): 40 (#4380) Canada-Labrador; 41 (#4396) USA-Alaska; 42 (#3856) Canada-Nunavut; 43 (#59) USA-Alaska; 44 (#43) Denmark- Greenland; 45 (#4740) Denmark-Greenland; 46 (#4407) USA-Alaska; 47 (#334) USA-Alaska; 48 (#285) Canada-Nunavut; 49 (#4383) USA-Alaska; 50 (#44) Denmark-Greenland; 51 (#19) Canada-Northwest Territories; 52 (#4401) USA-Alaska; 53 (#4403) USA-Alaska; 54 (#4884) Canada-Yukon; 55 (#4405) USA-Alaska; 56 (#4384) USA-Alaska; 57 (#4951) USA-Alaska; 58 (#29) Canada-Manitoba.

FIGURES 129‒137. Morphology of the male genitalia for species of the subgenus Alpinobombus from the dorsal aspect, anterior to the left of the image, posterior to the right: 129 B. alpinus (#3824); 130 B pyrrhopygus (#3833); 131 B. polaris (#73); 132 B. balteatus (#3843); 133 B. kirbiellus (#3768); 134 B. neoboreus (#4387); 135 B. kluanensis (#4876); 136 B. natvigi (#81); 137 B. hyperboreus (#3821).

FIGURES 140‒143. Morphology of females (queens). Left lateral aspect of the oculo-malar area of: 140, B. polaris; 141, B. kirbiellus (white lines indicate length and breadth measurements). Left lateral aspect of the outer surface of the left hind tibia (corbicular area): 142, B. polaris; 143, B. neoboreus (white lines indicate highlights in the central area).

FIGURES 144‒147. Morphology of males. Dorsal aspect of the penis valves of: 144, B. natvigi; 145, B. neoboreus (white lines indicate location of the subapical outer tooth of the left penis valve). Dorsal aspect of left gonostylus: 146 B. kirbiellus; 147, B. polaris (white lines indicate anterior, midpoint, and posterior median projections of left gonostylus).

FIGURES 22‒38. 22: Bombus pyrrhopygus global distribution (as for Fig. 15). 23‒38 colour patterns (as for Figs. 16‒21): 23 (#4707) Russia-Arkhangelsk; 24 (#337) Russia-Arkhangelsk; 25 (#273) Sweden; 26 (#272) Sweden; 27 (#250) Sweden; 28 (#249) Sweden; 29 (#258) Sweden; 30 (#4709) Russia-Murmansk; 31 (#257) Sweden; 32 (#4711) Russia-Arkhangelsk; 33 (#4712) Russia-Arkhangelsk; 34 (#4713) Russia-Arkhangelsk; 35 (#242) Norway; 36 (#139) Sweden; 37 (#4710) Norway; 38 (#1375) Russia-Murmansk.