Specimens of myxomycetes obtained as field collections or from moist-chamber cultures during surveys for these organisms carried out at several localities in New Zealand have yielded eight species not included in the monograph of the group published in 2003. One other species, listed provisionally as Diderma cf. miniatum on the basis of a single, rather limited collection, but now known from several additional collections, is described herein as Diderma novae-zelandiae. These new records bring the number of myxomycetes reported from New Zealand to 196 species.