Sladen, 1919, a Valid North American Bumble Bee Species, with a New Synonymy and Comparisons to Other "red-banded" Bumble Bee Species in North America (Hymenoptera, Apidae, Bombini)

The bumble bee (Hymenoptera, Apidae, Bombini, Latreille) fauna of the Nearctic and Palearctic regions are considered well known, with a few species occurring in both regions (i.e., with a Holarctic distribution), but much of the Arctic, especially in North America, remains undersampled or unsurveyed. Several bumble bee taxa have been described from northern North America, these considered either valid species or placed into synonymy with other taxa. However, some of these synonymies were made under the assumption of variable hair colour only, without detailed examination of other morphological characters (e.g., male genitalia, hidden sterna), and without the aid of molecular data. Recently, Martinet, Brasero & Rasmont, 2019 was described from Alaska where it is considered endemic; based on both morphological and molecular data, it was considered a taxon distinct from (Fabricius, 1793). was also considered distinct from Cresson, 1878, a taxon from Alaska surmised to be a melanistic form of Kirby, 1837, the North American subspecies (Martinet et al. 2019). Unfortunately, Martinet et al. (2019) did not have DNA barcode sequences (COI) for females of , but molecular data for a melanistic female specimen matching the DNA barcode sequence of the holotype of have been available in the Barcodes of Life Data System (BOLD) since 2011. Since then, additional specimens have been obtained from across northern North America. Also unfortunate was that B. sylvicola var. johanseni Sladen, 1919, another melanistic taxon described from far northern Canada, was not considered. is here recognized as a distinct taxon from Kirby, 1837 (Martinet et al. 2019) in the Nearctic region, showing the closest affinity to Friese, 1902 of the Old World. As the holotype male of is genetically identical to material identified here as , it is placed into synonymy. Thus, we consider a widespread species occurring across arctic and subarctic North America in which most females are dark, with rarer pale forms (i.e., "") occurring in and seemingly restricted to Alaska. In addition to showing molecular affinities to of the Old World, both taxa also inhabit similar habitats in the arctic areas of both Nearctic and Palearctic, respectively. It is also likely that many of the specimens identified as from far northern Canada and Alaska might actually be , so that should be considered for future studies of taxonomy, distribution, and conservation assessment of North American bumble bees.