Abstract
Oxydothis species are associated with monocotyledons including Arecaceae (palms), Pandanaceae, Poaceae (Bamboo) and Liliaceae and have been recorded as endophytes, pathogens and saprobes. Species of Oxydothis form singly or in clusters, as darkened, raised regions or dots on the surface of host. This paper clarifies the placement of Oxydothis and related species based on morphological characteristics and phylogenetic analyses using recent collections from Thailand. Oxydothis species are characterized by cylindrical asci, with a J+ (rarely J-) subapical ring and filiform to fusiform, hyaline, 1-septate ascospores, tapering from the center to spine-like, pointed or rounded ends. Phylogenetic analyses generated from maximum likelihood and Bayesian analysis of combined ITS, LSU and SSU sequence data indicate that Oxydothis species form a distinct lineage related to Vialaeaceae and Iodosphaeriaceae. We introduce a new family Oxydothidaceae in Xylariales with six new species based on morphological characteristics and phylogenetic analyses. We provided notes on the lifestyle of this genus which may throw light on the nature of many saprobic microfungi.