This paper is the third in a series revising the taxonomy of New Zealand dictyoceratid sponges (phylum Porifera, class Ceractinomorpha, order Dictyoceratida). Only one species ofIrciniahas previously been described from New Zealand,Ircinia novaezealandiaeBergquist, 1961. Six new speciesof Irciniaare added to New Zealand's known fauna. The genusIrciniacontains in excess of 40 published species worldwide, although the integrity of some of these is uncertain, often because of poor diagnoses. The diagnoses of new species reported here provide a model for the morphological descriptions of future species. The subdivisionof Irciniais also considered.