Abstract
During the investigation of epiphytic fungi on needles of Japanese red pine (Pinus densiflora) in Korea, eleven unknown Rhizosphaera strains were isolated. When compared with recorded Rhizosphaera species, the morphological and cultural characters of these isolates differed from existing published species and indicated that they belong to a taxon of their own. The new species was named R. densiflorae and its conidial size was larger than that of R. kalkhoffii and smaller than that of R. pseudotsugae. The new species grew between 5 degree celsius and 35 degree celsius with an optimum growth at 25 degree celsius, whereas R. pseudotsugae showed an optimum growth at 18 degree celsius and did not grow at 22 degree celsius and above. The phylogenies of ITS and beta-tubulin sequences differentiated the new species from other Rhizosphaera species. The trees produced from ITS and beta-tubulin data were identical, but the beta-tubulin tree yielded better resolution and was more strongly supported than the ITS tree by bootstrap analysis. Moreover, the trees supported that the classification of Rhizosphaera species based on the conidial size was phylogenetically significant. In the systematic studies of Rhizosphaera, molecular data apparently played an important role in resolving the true phylogeny of morphologically similar or taxonomically related isolates
