Parmotrema internexum is shown to be a morphologically, chemically and phylogenetically distinct species whose occurrence in North America has been previously overlooked and largely based on misidentifications. Prior accounts of the species being similar to P. crinitum but differing in having an adnate thallus, few marginal cilia, and in producing norlobaridone in addition to the stictic acid complex, are confirmed. An extensive review of the taxon, including the use of the name P. internexum in the literature, is provided. Taxonomic treatments of P. crinitum and P. internexum are also provided and both species are illustrated.