River basins
For Odonata, river basins were used by the specialist group to delineate species range limits, and, consequently (Figure S2b), when only the ranges designated by the specialist group are analysed, >92% of range boundaries fall on river basin boundaries including a 1km buffer (Table S1). This is not the case for newly-added species (largely Latin American), which clearly use a different, less spatially-precise approach, and only 74.3% of their boundaries fall on river basin boundaries.