Baetis (Rhodobaetis) canariensis s.l. was considered to be the most common species of mayfly (Ephemeroptera) in running waters of the Canary Islands. Recent studies using mitochondrial genetic markers suggested that what was considered a single species was in fact composed of four closely related, but distinct species. Here we present the results of comprehensive morphological analysis of specimens from Tenerife, Gran Canaria, La Palma, and La Gomera that confirms the validity of the four species based on small but consistent differences in some characters. Three of these are new species and are described herein at the larval stage. Each of the four species appears to be restricted to a single island. The loss of freshwater habitats on the islands has led to a drastically diminished distribution and these species are largely restricted to protected areas in national parks. All four species must be considered endangered and are very sensitive sentinels of the state of conservation of running waters.

Baetis gomerensis, B. palmensis, B. tenerifensis, conservation, DNA barcoding, La Gomera, La Palma, Macaronesia, mayflies, new species, Tenerife