Ecuadorian bumble bees (Apidae: <i>Bombus</i>): Species diversity, distribution, and floral associations

Ecuador’s bee diversity, particularly bumble bees, remains underexplored despite their significant ecological role. This study provides an updated species list, identification keys in both English and Spanish, potential distribution maps based on Ecological Niche Models (ENM), and a summary of known plant associations. Our dataset includes 1,756 records, comprising 408 museum specimens, 1,234 observations from iNaturalist, and 114 field observations recorded by the first author. We document 13 species distributed across two subgenera. Bombus (Cullumanobombus): B. butteli, B. ecuadorius, B. funebris, B. handlirschi, B. hortulanus, B. melaleucus, B. robustus, B. rubicundus, and B. vogti. Bombus (Thoracobombus): B. excellens, B. pauloensis, B. pullatus, and B. transversalis. Most species are associated with high Andean ecosystems above 2,300 m, though several extend into lower elevations, with records ranging from 180 to 4,719 m. The compiled data span five decades and include records from 17 of 24 provinces in Ecuador. Bumble bees were documented visiting 143 plant species across 39 families, highlighting their broad trophic interactions and potential importance for native vegetation. The ENM-based potential distribution maps offer updated insights into the geographic ranges of those species with sufficient occurrence data, providing a foundation for future ecological and conservation assessments. This study synthesizes the most comprehensive information currently available on Ecuadorian bumble bees, contributing to improved taxonomic knowledge, a deeper understanding of their trophic interactions, and clearer biogeographic insights for the group. Our findings also highlight the importance of continued monitoring and research, particularly to evaluate how these species respond to environmental change and to better understand their functional roles within both Andean and lowland ecosystems.