Fissuroma (Aigialaceae: Pleosporales) appears to be hyperdiverse on Arecaceae: evidence from two new species from southern Thailand

Thailand and other tropical regions have high fungal diversity. Our investigation and examination of microfungi on palms (Arecaceae) revealed two new ascomycetous species of Fissuroma. Fissuroma arengae and F. wallichiae spp. nov. are introduced using morphological and phylogenetic evidence. The novel species have coriaceous ascomata, cylindrical-clavate asci and ascospores with a distinct and thin mucilaginous sheath. Fissuroma arengae is similar to F. wallichiae but can be distinguished by minor morphology, host substrate and gene base-pair differences. Phylogenetic analyses of combined LSU, ITS, SSU, tef1-alpha and rpb2 sequence data showed that these strains grouped within Fissuroma, further confirming this genus as monophyletic. The two new species are described and illustrated to support their taxonomic placement. Fissuroma appears to be a highly diverse genus often occurring on palms. It is likely that more research will result in numerous new taxa being discovered.