Phylogenetic study of Hypoxylon and related genera based on ribosomal ITS sequences

Hypoxylon, with at least 130 currently accepted species and varieties, is one of the largest genera of the Xylariaceae. Taxonomic aspects that define and delimit the genus have varied among mycologists. To obtain insight in the phylogenetic relationships of Hypoxylon and its allies, the complete DNA sequences of the internal transcribed spacer region (including the 5.8S rRNA gene) from 41 isolates were determined, aligned and processed for phylogenetic reconstruction, and critically compared with the available taxonomic information. The results generally agree with the current concepts and limits established for the genus. The molecular approach supported the recent segregation of some allied genera (Biscogniauxia, Camillea, Whalleya, Creosphaeria, Nemania, and Kretzschmaria) from Hypoxylon. The species and varieties of Hypoxylon in the sense of modern authors appeared as a monophyletic group within the Xylariaceae. However the recent infrageneric division of Hypoxylon into sections Hypoxylon and Annulata was not supported by this limited molecular phylogenetic analysis. Likewise, this preliminary analysis did not reflect generic distinctions among species in genera with bipartite stromata (Camillea and Biscogniauxia). The importance of the anamorphs in the classification of this fungal group was evidenced by the correlation between the type of anamorph and the relative placement of the teleomorphs in the phylogenetic tree derived from sequence analysis.