The new species Oxylobus coyulensis, currently only known from the Tehuacan-Cuicatlan Valley Biosphere Reserve, located in the states of Oaxaca and Puebla, Mexico, is described. The new taxon can be distinguished from the other species of the genus by leaf shape, leaf trichome diversity, and cypselae surface characteristics. In addition, following a detailed micromorphological study of the species within this genus, it was found that O. juarezensis and O. subglabrus present the same leaf trichome diversity, similar cypselae surface characteristics, and similar macromorphological characters, namely leaf shape and margins, phyllaries, and inflorescence type. As a consequence, it is concluded that O. juarezensis is synonymous with O. subglabrus, as moreover, they are distributed in the same geographical area.