Bombus (Pyrobombus) johanseni 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)

Abstract

The bumble bee (Hymenoptera, Apidae, Bombini, Bombus 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, Bombus interacti 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 B. lapponicus (Fabricius, 1793). Bombus interacti was also considered distinct from B. gelidus Cresson, 1878, a taxon from Alaska surmised to be a melanistic form of B. lapponicus sylvicola 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 B. interacti, but molecular data for a melanistic female specimen matching the DNA barcode sequence of the holotype of B. interacti 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. Bombus johanseni is here recognized as a distinct taxon from B. lapponicus sylvicola Kirby, 1837 (sensu Martinet et al. 2019) in the Nearctic region, showing the closest affinity to B. glacialis Friese, 1902 of the Old World. As the holotype male of B. interacti is genetically identical to material identified here as B. johanseni, it is placed into synonymy. Thus, we consider B. johanseni a widespread species occurring across arctic and subarctic North America in which most females are dark, with rarer pale forms (i.e., “interacti”) occurring in and seemingly restricted to Alaska. In addition to B. johanseni showing molecular affinities to B. glacialis 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 B. lapponicus sylvicola from far northern Canada and Alaska might actually be B. johanseni, so that should be considered for future studies of taxonomy, distribution, and conservation assessment of North American bumble bees.