Species, study area & species locations
Four species are particularly known for their link to cold areas and for their rarity: Bombus alpinus helleri , Bombus mendax ,Bombus mucidus and Bombus konradini . Bombus (Alpinobombus) alpinus (Linnaeus, 1758) has a disjoint distribution, as the subspecies alpinus occurs in the high Fennoscandia andhelleri occurs in the Alps at the highest elevation and formerly in the Carpathians, where it is now considered extinct (Rasmont et al. 2015, Biella et al. 2017). Bombus (Mendacibombus) mendaxGerstaecker, 1869 occurs at the highest elevation of the Alps with the subspecies mendax (Amiet et al. 2017) and of the Pyrenees with the subspecies latofasciatus Vogt 1909 (Ornosa et al. 2017), with a few more records on the Cantabrian mountains(Santamaría et al. 2011).Bombus (Mucidobombus) mucidus Gerstaecker, 1869 occupies the middle and high elevations of the Alps and of the Apennines (Manino et al. 2007), it occurs in the Pyrenees and it occurs also locally on the Cantabrian Range (Ornosa et al. 2017) and patchily in the Balkans and the Carpathians (Rasmont et al. 2015). Bombus (Pyrobombus) konradini Reinig 1965 (i.e. the central Apennines populations of the formerly known Bombus monticola konradini ) occurs exclusively at the high elevations of the central section of the Apennines and little is known on its ecology (Ricciardelli D’Albore and Piatti 2003).
The study area encompasses the Alps, the Apennines and the Pyrenees. Occurrence locations were retrieved from the literature, private and museum collections, with details available in supporting text A1. The coordinates of the records were visually validated with satellite images (i.e. corresponding to alpine areas in a broad sense and within the known elevational range of the species); unlabelled, inconsistent, dubious or duplicated data were excluded. Cumulatively, 1771 data were available for the analyses: 172 for B. alpinus , 722 for B. mendax , 826 of B. mucidus and 50 of B. konradini from the Alps, Apennines and Pyrenees study areas (we excluded the Cantabrian Range and Balkans because of too scattered and mostly old records available from there). As the investigated species are large and conspicuous, they are unlikely to go undetected and these available records are representative for describing the distribution with sufficient accuracy. The datasets used in the analyses constitute the most comprehensive ones available for the study species.