Five new species of cyanobacteria, Scytonematopsis maxima, Tolypothrix pseudorexia, Hormoscilla irregularis, Phormidium arthurensis, and Godleya alpina, the last belonging to a new genus, are described from cultured material isolated from the alpine zone of Mt Philistine, New Zealand. Tolypothrix pseudorexia resembles Rexia erecta in formation of upright trichomes on agar, but clearly lacks the ability to divide in two planes that is characteristic of the latter species. Godleya displays characteristics of the Scytonemataceae-isopolar hormogone development and binary branching-but groups with a species of Coleodesmium (Microchaetaceae) in analyses of 16S rDNA, despite its morphological differences, thus conflicting with the current classification system. We also show that material referable to the widely reported species Phormidium autumnale is found in the New Zealand alpine zone; molecular data indicate that this is likely the same organism reported recently from the Hutt River, Wellington, New Zealand, a quite different habitat. In this site, a lowland river, the species may form extensive mats. These have not been seen on Mt Philistine.