New species and phylogenetic relationships of Hypoxylon species found in Thailand inferred from the internal transcribed spacer regions of ribosomal DNA sequences

Hypoxylon specimens collected from different forest areas in Thailand were investigated and identified to species using both morphological and molecular characteristics. Fifteen species, including three new species, H. kanchanapisekii, H. sublenormandii, and H. suranareei, were recorded. The phylogenetic tree of the Hypoxylon examined was constructed using the neighbour-joining method based on the internal transcribed spacer (ITS) regions including 5.8S ribosomal DNA sequences. The molecular results revealed clear separation among Hypoxylon species including closely related species or on data based only on teleomorphic DNA. Three taxa in Hypoxylon sect. Annulata-H. nitens, H. purpureonitens, and H. bovei var. microspora-were grouped together, but the fourth species, H. cf archeri, was separated. The phylogenetic tree does not support the monophyletic group of sect. Annulata in this study. In addition, these molecular data could be used to confirm the recognition of new species based on morphological features and they are valuable for the creation of the Hypoxylon DNA sequence database.