Bombus hyperboreus Schönherr

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 : 44-47

9. Bombus hyperboreus Schönherr

( Figs. 6 , 124‒128 , 137 )

Apis Arctica Quensel in Acerbi 1802:253 , type-locality citation ‘Lapland’. Holotype queen (#5015) by monotypy, NHRS examined PW, ‘ FINLAND, Lapplands’ (Lapland, Finland). Notes 1, 2. Synonymised (with question mark) with Bombus hyperboreus Schönherr by von Dalla Torre (1896:524); synonymised with Bombus hyperboreus Schönherr by Løken (1973:114). Nomen oblitum.

Bombus hyperboreus Schönherr 1809:57 , type-locality citation ‘Lapponia Tornenfi, circa Enontekis’. Holotype queen (#4844) by monotypy, NHRS examined PW, ‘ FINLAND, Lapplands’ (Lapland, Finland). Objective junior synonym, see Nilsson (2009). Note 2. Nomen protectum.

[< Alpinibombus hyperboreus > mod. cilifer, mod. latebalteatus, ab. flavocorbiculosus Skorikov 1937:57, infrasubspecific.]

Note 1 ( arcticus ). Nilsson (2009:53) described the history of the single type specimen of Apis arctica Quensel (spelled Quenzel in the original publication).

Note 2 ( hyperboreus ). Nilsson (2009:53) gave an account of the redescription of the type specimen of Apis arctica Quensel as Bombus hyperboreus Schönherr , which is therefore an objective junior synonym. Milliron’s (1960:93) designation of the single original specimen as lectotype is invalid as stated by Løken (1973:114; agreed by Nilsson 2009:53), because in the original description the species was identified as having been based on a single specimen, which is therefore the holotype by monotypy (#4844). Løken (1973:114) considered B. arcticus (Quensel) to be a nomen oblitum, so she continued to use the name B. hyperboreus Schönherr. However , nomina oblita are not supported for a publication of the date of Løken’s work (after 1 January 1973) by the now current Code ( ICZN 1999:111), although this status could be supported after 1 January 2000 as recognised later by Nilsson (2009:54) according to this Code ( ICZN 1999: Article 23.9). There is strong support for the claim that B. hyperboreus Schönherr is the stable valid name because both criteria required by the current Code ( ICZN 1999) are essentially met: first (Article 23.9.1.1), that the senior synonym B. arcticus (Quensel) has not been used as a valid name after 1899 (most uses of B. arcticus for this species being instead misidentifications of B. arcticus Kirby following Franklin 1913:302; which according to Richards 1931:9, include Meade-Waldo 1916:469, Sladen 1919:28, and Lutz & Cockerell 1920:507), with the sole exception of Michener (2000:789); and second (Article 23.9.1.2), that the junior synonym B. hyperboreus Schönherr has been used for this well known taxon as its presumed valid name in more than 25 works, published by at least 10 authors in the preceding 50 years (since 1968: e.g. Richards 1968; Løken 1973; Sakagami 1976; Svensson & Lundberg 1977; Pekkarinen 1979; Pekkarinen et al. 1981; Reinig 1981; Rasmont 1983a; Williams 1989, 1991; Pekkarinen & Teräs 1993; Williams 1998; Koulianos & Schmid-Hempel 2000; Pedersen 2002; Goulson 2003; Hines et al. 2006; Cameron et al. 2007; Holmström 2007; Gjershaug 2009; Nilsson 2009; Ebmer 2011; Mossberg & Cederberg 2012; Rasmont & Iserbyt 2012; Cederberg et al. 2013c; Potapov et al. 2014; Ødegaard et al. 2015; Rasmont et al. 2015). The use by Michener (2000) of B. arcticus (Quensel) as the valid name (contrary to the recommendations of Løken 1973:114, and of Williams 1998:119) can be construed as deliberately contrary to Article 23.9.1 because he wrote that the species is ‘usually known as’ B. hyperboreus Schönherr , so that this instance of usage can be discounted ( ICZN 1999: Article 23.9.6). Therefore we consider Bombus hyperboreus Schönherr to be the valid name for this species.

Taxonomy and variation. Bombus hyperboreus has long been considered to include B. natvigi but has been recognized as separate from evidence of a species coalescent in the COI gene ( Williams et al. 2015; Fig. 9 ). The support from bGMYC analysis for separation of B. kluanensis , B. natvigi , and B. hyperboreus , was not as high as for the other species of Alpinobombus ( Williams et al. 2015), but B. kluanensis is easily distinguished by its social behaviour with abundant workers. Bombus hyperboreus is vicariant with B. natvigi across the Bering Strait ( Figs. 116 , 124 ).

Variation in the colour pattern has been analysed previously ( Williams et al. 2015). There is very little variation in this species and this is primarily in the hue of the pale bands, from pale yellow on Wrangel Island ( Fig. 125 ) to the more common chestnut brown ( Figs. 126, 128 ).

Material examined. 70 females 1 worker 92 males, from Norway, Sweden, Finland, and Russia ( Fig. 124 : AB BP FO MB NHMUK NHRS PW YPM ZISP), with 16 specimens barcoded.

Habitat and distribution. Flower-rich arctic/alpine tundra in the Old World from the far north of Scandinavia, Taymyr, Novaya Zemlya and Wrangel Island, extending southwards into the subarctic region in the alpine zone of the Magadan and Scandinavian mountains. Regional distribution maps ( Løken 1973; Richards 1973; Pekkarinen et al. 1981; Rasmont & Iserbyt 2012; Ødegaard et al. 2015; Rasmont et al. 2015).

Food plants. ( Richards 1931; Richards 1973; Mossberg & Cederberg 2012)

Behaviour. Bombus hyperboreus is almost unique among bumblebees other than species of the subgenus Psithyrus (the other exceptions are B. natvigi , above, and B. inexspectatus (Tkalců) , see Müller 2006) in being recorded as a parasite in colonies of other bumblebees. The host species is especially B. pyrrhopygus (under the name B. polaris, Friese 1935 ; Løken 1973; Pape 1983), but there are also recent records as hosts for B. balteatus ( Gjershaug 2009) , and B. (Pyrobombus) jonellus (Kirby) ( Bergwall 1970) . Five females of B. hyperboreus in the NHMUK collection (#182, 189, 197, 198, 200) have substantial amounts of compressed pollen in their corbiculae, which appears to be evidence of foraging for a colony, as reported previously from Europe ( Gjershaug 2009). Pollen in a corbicula is also shown for the female in Fig. 6 , which is foraging on Astragalus alpinus L.. Females have been observed showing ‘nest-seeking’ behaviour ( Svensson & Lundberg 1977). Some authors have reported workers of B. hyperboreus ( Enwald 1881; Skorikov 1923; Elfving 1960; Løken 1973), but we have seen only one convincing worker of this species in this study, from Norway (#3855) ( Ødegaard et al. 2015). There is no evidence of mimicry of the host ( B. pyrrhopygus ) in cephalic gland secretions and none of the repellent compounds identified from parasitic Psithyrus bumblebees were detected ( Brasero, Martinet, et al. 2017).

Conservation status. This species has been assessed for Red List threat status using IUCN criteria (2001). Cederberg et al. (2013c) assessed the Red List status of this species in Europe as ‘Vulnerable’ because its known area of occupancy (AOO) for Europe is small (420 km ²) and because it is experiencing a continuing decline due to declines in its host, B. pyrrhopygus (under the name B. polaris ), and climate warming. Subsequently, Rasmont et al. (2015) have assessed the risk from climate change to this species in Europe as ‘extremely high climate change risk’ (HHHR), projecting that climate change will very likely lead to its extirpation from Europe.

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 124‒128. 124: Bombus hyperboreus global distribution (as for Fig. 15). 125‒128 colour patterns (as for Figs. 16‒ 21): 125 (#39) Russia-Chukotka (Wrangel Island); 126 (#33) Russia-Magadan; 127 (#1258) Russia-Murmansk; 128 (#533) Russia-Sakha.

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 116‒123. 116: Bombus natvigi global distribution (as for Fig. 15). 117‒123 colour patterns (as for Figs. 16‒21): 117 (#3519) Canada-Nunavut; 118 (#184) Canada-Nunavut; 119 (#3551) Canada-Nunavut; 120 (#3546) Canada-Nunavut; 121 (#79) USA-Alaska; 122 (#3557) Canada-Northwest Territories; 123 (#82) Canada-Northwest Territories.