28th Mexican studies on Rubiaceae. Coussarea aubl. (Coussareae) genus with two new species in Mexico [Estudios sobre Rubiáceas Mexicanas XXVIII. El género Coussarea aubl. (Coussareae) en México con dos especies nuevas]

摘要

Coussarea is a neotropical genus including over 100 species of trees and shrubs. In the flora of Mexico it has been represented by a unique species, C. mexicana. Recently two new species appeared from collections made in Chiapas and Oaxaca states, which have two characters uncommon in the genus, namely the C. chiapensis has 5-merous flowers and the C. rafa-torresii has unisexual dioiceous flowers, while the overwhelming majority of the Coussarea species has bisexual, 4-merous flowers. Therefore it turned to be necessary to modify the generic description.