Microsatellite markers were used to test whether two recently described species of Sphagnum (Bryophyta), S. atlanticum R.E. Andrus and S. bergianum R.E. Andrus, represent distinct gene pools. The first species is considered endemic to eastern North America while the second species has been reported from Alaska and Newfoundland. The results indicate that S. atlanticum does not differ genetically from the closely related species, S. torreyanum, also restricted to eastern North America. In fact, some samples that are identical across all 15 micro-satellite loci have been distinguished morphologically as these two species. Plants of S. bergianum from Alaska are closely related genetically to Alaskan plants of the similar species, S. subfulvum, whereas Newfoundland plants of S. bergianum are more closely related to Newfoundland plants of S. subfulvum. Alaskan versus Newfoundland plants of S. subfulvum s.l. (including S. bergianum) are differentiated at microsatellite loci. Another closely related species, S. subnitens, is distinct from S. subfulvum and S. bergianum. Sphagnum atlanticum is synonymized under S. torreyanum and S. bergianum is synonymized under S. subfulvum.