Brickellia nesomii, a new species from northeastern Mexico, is described. It belongs to the subgenus
Phanerostylis, which Gray originally placed in
Eupatorium; King and Robinson elevated the taxon to generic rank; it is herein kept at the subgeneric level but transferred to
Brickellia. Reasons for this transfer are given.
Barroetea glutinosa, positioned by King and Robinson in
Phanerostylis, is excluded.