New Plant Discoveries for Sonoran Islands, Gulf of California, Mexico

Renewed botanical interest in the Sonoran islands of the Gulf of California (Islas Tiburón, San Esteban, San Pedro Nolasco, Dátil, and Alcatraz) as part of our project, “Botanical Diversity of Isla Tiburón and Satellite Islands, Gulf of California,” has resulted in 61 new ad- ditions and distributional clarifications to the floras of these islands. These new records represent increases of 16% for Tiburón, 4% for San Esteban, 3.5% for San Pedro Nolasco, 3% for Dátil, and 12% for Alcatraz over the most recently published checklists. We also report three new records for the Sonora mainland. On Isla Tiburón the majority of the new additions are from the deep canyons and peaks of the extensive Sierra Kunkaak on the east side of the island, which highlight the sheltered habitats of the Sierra and their accordingly strong connection with more tropically inclined floras. For all islands, the new records expand our understanding of this region and represent intriguing distributional extensions for those species. The current floristic work on the Sonoran islands is significantly adding to the understanding of the biogeographical relations of these islands, as well as to their current status within a region facing increasing threats from development and invasive species.