The genus Oxydothis: New palmicolous taxa and phylogenetic relationships within the Xylariales

Abstract

Oxydothis (Xylariales) is an ascomycete genus, commonly encountered on decaying monocotyledons, such as palms. During our study on diversity of palmicolous fungi in northern Thailand, we encountered three new species of Oxydothis: O. cyrtostachicola, O. inaequalis and O. wallichianensis, and these are described and illustrated in this paper. The three novel species differ from other morphologically similar Oxydothis species in ascomata shape and ostiole position, ascal ring, and ascospore morphology. Phylogenetic affiliations of the new taxa with members of related ascomycete families within the Xylariales are discussed based on morphology and nrDNA sequence data. The phylogenetic relationships of Oxydothis and its familial placement remain obscure based on the 28S nrDNA sequence analyses. Large sub unit nrDNA (28S) gene sequences do not provide significant phylogenetic information concerning the evolutionary relationships of these xylariaceous fungi. ITS nrDNA sequence analyses, however, indicate that Oxydothis is more closely related to members of the Amphisphaeriaceae than Diatrypaceae or Xylariaceae.