A worthy conservation target? Revising the status of the rarest bumblebee of Europe

Abstract

Against the context of global wildlife declines, targeted mitigation strategies have become critical to preserve what remains of biodiversity. However, the effective development of conservation tools in order to counteract these changes relies on unambiguous taxonomic determination and delineation. In this study, we focus on an endemic bumblebee species recorded only from the highest altitudes of the Sierra Nevada (Spain), Bombus reinigiellus (Rasmont, 1983). The species has the smallest range of any European bumblebee, along with a restricted diet and an inability to disperse because of its isolated montane distribution, making it an appropriate conservation target. However, through an integrative taxonomic approach including genetics, morphometrics and semio‐chemistry, we demonstrate the conspecificity of this taxon with one of the most common and widespread bumblebee species of Europe, Bombus hortorum (L. 1761). We assign a subspecies status to this endemic taxon (Bombus hortorum reinigiellus comb. nov.) shown to be different in colour and morphology but also in wing shape and relative wing size compared to the other conspecific subspecies. Following our taxonomic revision, we reassessed the IUCN conservation status of Bombus hortorum both at the continental and Spanish scale. We then propose how historic climatic oscillations of the last Ice age could explain such a phenotypic divergence in a post‐glacial refugium and highlight the critical role of establishing unambiguous taxonomic revision prior to any conservation assessment.

Insects as indicators of Key Biodiversity Areas

“…The subject of whether or not subspecies should be considered valuable biological units in conservation biology, and how, has been discussed extensively over the years (Braby et al, 2012; Haig et al, 2006; Patten, 2015; Phillimore & Owens, 2006). For invertebrates in particular, it has been suggested how subspecies represented by isolated allopatric populations, with a distinct phenotype which is correlated with an evolutionary independence should be evaluated as significant biodiversity units for conservation (Braby et al, 2012; Ghisbain et al, 2021). The global standards for the identification of KBAs allow the detection of KBAs for subspecies solely through an assessment of their distinct genetic diversity (IUCN, 2016; KBA Standards and Appeals Committee of IUCN SSC/WCPA, 2022).…”

National records of 3000 European bee and hoverfly species: A contribution to pollinator conservation

“…Fundamental taxonomic research remains the basis for all subsequent work, from monitoring to species conservation (Ghisbain, Martinet, et al, 2021; Ghisbain, Rosa et al, 2023). Considering the great diversity of insects (including pollinators), more taxonomic work is needed together with the development of taxonomic tools for the relevant groups, both crucial to the understanding of ecology, biogeography and conservation status (Hochkirch et al, 2021; Nieto et al, 2014).…”

Book review: The Bumblebees of the Himalaya – An Identification Guide, by Paul H. Williams

“…the case of B. konradini, Martinet et al 2018; and other cases recently presented by the author in his works Williams et al 2020;Williams 2021). As this scenario is relatively common in bumblebees (many species indeed show a high degree of crypticism: Ghisbain et al 2020Ghisbain et al , 2021Williams 2021), properly naming entities with different phenotypic aspects can be helpful for future research. Finally, because subspecies can be recognized as valid taxonomic entities that can receive conservation measures following the IUCN standards, presenting them in identification guides could be useful to allow their monitoring at local scales.…”