Abstract
Species of Mycosphaerella and their related anamorphs represent potentially serious foliar pathogens of Eucalyptus. The fungi treated in the present study were isolated from symptomatic Eucalyptus leaves collected in Thailand during June-October 2007. Species were initially identified based on morphological and cultural characteristics. Identifications were confirmed using comparisons of DNA sequence data of the internal transcribed spacers (ITS1, 5.8S nrDNA, ITS2) and the 28S nrDNA (LSU) regions. To help distinguish species of Pseudocercospora, the dataset was expanded by generating partial sequences of the translation elongation factor 1-alpha and actin genes. By integrating the morphological and molecular datasets, five new taxa were distinguished, namely Mycosphaerella irregulari, M. pseudomarksii, M. quasiparkii, Penidiella eucalypti and Pseudocercospora chiangmaiensis, while M. vietnamensis represents a new record for Thailand.