This species is often recognized by its characteristic densely pilose to hirsute pubescence, but as in many other Rubiaceae species occasional plants are glabrous (e.g., McPherson & van der Werff 16360). This species is similar to Gaertnera hispida. The name G. crinita was lectotypified by Malcomber & Taylor (2009). Gaertnera phanerophlebia may hybridize with other species of Gaertnera; in particular one specimen, P.J. Rakotomalaza et al. 2068, appears to represent a hybrid with either G. humblotii or G. raphaelii.