Megacorax gracielanus (Onagraceae), a new genus and species from Durango, Mexico

Megacorax gracielanus, a distinctive new genus and species from the Sierra de Coneto in central Durango, Mexico, is described and illustrated. Its distinctive characters include: leaves linear, petals presented to one side of the flower, and capsule wall thin and distended by the seeds. It appears to be most closely related to Lopezia Cavanilles based on possession of 4-merous flowers, deciduous sepals, a capitate stigma, stipules, and a tendency toward the structural zygomorphy in the flowers found in Lopezia. In addition, the capsules of Megacorax gracielanus are very similar in shape and structure to the capsules of certain species of Lopezia. Because Megacorax has distinctive morphological characters and does not have the unique synapomorphies of Lopezia (2 fertile stamens or 1 fertile stamen and 1 staminode, and petals unequal), it is here described as a related genus.