Abstract
<jats:p>Ectomycorrhizal (EcM) fungi play critical roles in global carbon and nutrient cycling. In Canada, vast forest ecosystems dominated by EcM trees are experiencing rapid environmental and anthropogenic change that threaten the symbiosis. Here we quantify and discuss seven biodiversity data shortfalls that constrain our knowledge of EcM fungi in Canada, and impede the development of effective conservation plans. We based our assessments on publicly accessible sequence data from GlobalFungi and GenBank, filtered to samples within Canada. We found 2,805 unique EcM fungal species hypotheses, of which only 58% could be assigned a species name. The 1,405 unique named species comprised 124 genera, roughly 38% of the genera known globally. An overriding shortfall is that samples are lacking from large areas of the country, and with respect to both abiotic and biotic niche space. For example, host information is missing or unresolved for 73% of the named species, and among 1,002 species georeferenced in GlobalFungi, 50% have 5 or fewer occurrence records nationally. Although our assessment highlights large biodiversity data shortfalls for EcM fungi in Canada, it also provides the foundation for a coordinated, pan-Canadian sampling effort that can be optimized to address multiple shortfalls simultaneously.</jats:p>