Background:

During the revision of Gonolobus for Mexico, it was observed that G. fuscus, G. luridus, and G. tingens lack the staminal appendages and faucal ring typical of the genus. The observed specimens of these species have glandular trichomes, which become crystalline and white with age, and the double gynostegial corona characteristic of Polystemma, so their transfer to this genus is proposed.

Questions:

Do the morphological data support the transfer of the species studied here from Gonolobus to Polystemma? Are the plants studied here cospecific with any of the species known for Polystemma?

Species studied:

G. fuscus, G. luridus, and G. tingens.

Location and years of study:

Mexico.

Methods:

Protocols, digital images, and herbarium specimens of Gonolobus, and specialized literature were reviewed. Morphological comparisons were made with Mexican species of Gonolobinae, using the cohesive species concept.

Results:

The transfer of two species of Gonolobus to Polystemma is here proposed, as well as the synonymization of Gonolobus tingens Decne., Gonolobus suberifer B.L. Rob., Matelea suberifera, and M. crenata.

Conclusions:

With these taxonomic adjustments, Polystemma reaches 14 species, highlighting Mexico as the main center of diversity of the genus.