How many bee species are there? A quantitative global estimate

Robust species richness estimates are critical for meaningful conservation prioritization, understanding ecosystem resilience, and studying evolutionary processes ^1-4 . Yet, they remain elusive even for some of the best-studied groups and regions ⁵ . As keystone pollinators, bees are crucial for the maintenance of healthy ecosystems, yet what estimates exist are haphazard and derived from guesswork. We statistically estimated global, continental, and country lower bounds of species richness. Globally, we estimated 24,705–26,164 bee species, an 18–25% increase, representing at least 32–45 years of taxonomic research. Particularly high undescribed biodiversity is expected from Asia, Africa, and the Americas. Taxonomic gaps correlate with GDP per capita, observed species richness, number of occurrence records, and completeness of occurrence databases. Our statistical R-package framework ⁶ promises to progress understanding lesser-known groups, downstream consensus and, at long last, estimate the number of species on Earth.