Abstract
A new Mexican species of Spigelia (Loganiaceae), distributed in the states of Guerrero and Michoacán, is here described. The new species can be distinguished from the similar-looking S. humboldtiana by its corolla with innerly purple lobes, inserted stamens above the proximal half of the corolla tube and exserted style. With this contribution, Mexico reaches a total of 20 species, of which 50% are endemic, highlighting this country as a center of diversity for this genus. A dichotomous key for the species recorded in the states of Guerrero and Michoacán is included.