Two new species of Aphyllon from northeastern Mexico: Sequence alignments and phylogenetic trees

Plants originally identified as Aphyllon ludovicianum that occur near Monterrey, Nuevo Leon, and Cuatro Ciénegas Bolson, Coahuila, Mexico, were found to not align with the protologue of that species, the close relative A. multiflorum, or any other species of Aphyllon. Following a detailed study of floral morphology, geographic range, host species, and phylogenetic position using dry herbarium specimens, field study and georeferenced color photographs, we propose the new binomials Aphyllon spectabile for the plants from Nuevo Leon and Aphyllon gypsophilum for the plants from Coahuila, Mexico. This increases the taxonomic diversity of Aphyllon to 27 species plus ten additional subspecies. Gymnosperma glutinosum and two species of Xanthisma were reported for the first time as a host species for the genus Aphyllon. We also provide an updated key to Aphyllon in Mexico.