DNA relatedness among species of Geotrichum and Dipodascus

Abstract

The relatedness among species maintained as Geotrichum and Dipodascus (imperfect and perfect states) from their morphology, physiology, and ascomycetous characters was studied by techniques of nuclear genome comparison in combination with nuclear deoxyribonucleic acid base composition. Geotrichum fici exhibited 95% DNA base sequence complementarity with G. fragrans and was considered synonymous with G. fragrans. Two G. penicillatum strains exhibited 97–100% base sequence complementarity with G. klebahnii, and G. penicillatum is thus a later synonym of G. klebahnii. Geotrichum capitatum, G. klebahnii (which has priority over G. penicillatum), G. armillariae, and G. fragrans (which has priority over G. fici) can be considered as separate species and different from the type, G. candidum. Dipodascus geotrichum, which is considered the perfect state of G. candidum, showed a low but significant relationship to its proposed anamorph (about 45% relative binding of its DNA), but no other associations between perfect and imperfect forms could be detected. Our results suggest that in addition to current taxonomic criteria DNA comparisons also appear to be extremely valuable in making phylogenetic comparisons.