New species of Tibouchina (Melastomataceae) in Guerrero, Mexico

Abstract

Tibouchina araneicalyx is described and illustrated from the Pacific slopes of the Sierra Madre del Sur in Guerrero, Mexico. Its possible relationships with T. mexicana (D. Don) Cogniaux and another Mexican species of Tibouchina with pentamerous flowers and strongly dimorphic stamens are discussed, it is principally distinguished from these species by the sharply tetragonal branches, the triangular calyx lobes shorter than the hypanthium, and the petals with eglandular cilia.