Bourreria franciscoi(Ehretiaceae, Boraginales), a new species of arboreal Bourreriafrom Sinaloa, Mexico

Bourreria franciscoiis proposed and illustrated as a new species belonging to the B. huanitaspecies group. It was collected in the municipality of Cosalá, Sinaloa, in an area highly endangered by mining. The new species resembles Bourreria longifloraand B. rekoi, especially by its hypocrateriform corolla, but can be distinguished by elliptical-lanceolate leaves, size and shape of calyces, size and arrangement of the corolla lobes and androecium, and by the disjunct geographic distribution of these three species. A comparative chart and illustrations of related species are presented, as is a key for the identification of the species in the B. huanita-group and all Bourreriaspecies from Sinaloa.