Xenochalara, a new genus of dematiaceous hyphomycetes for chalara-like fungi with apical wall building conidial development
Ceratocystis autographa Bakshi is unusual amongst the ophiostomatoid fungi in that it produces two distinct anamorphs, typifying different teleomorph genera. A chalara-like anamorph characteristic of the genus Ceratocystis sensu stricto Ellis and Halst. and a Sporothrix Hektoen and C.F. Perkins anamorph typical of the genus Ophiostoma Syd. and P. Syd., have been described for the fungus. In a recent study, an isolate resembling C. autographa, that was collected from Juniperus L., was shown to have a different type of conidiogenesis to that of typical species of Chalara (Corda) Rabenh. Furthermore, cycloheximide tolerance and the presence of rhamnose in the cell walls of this isolate also suggested that it was more closely related to Ophiostoma than to Ceratocystis s. str. Parsimony analysis of ribosomal DNA sequence data in this study showed that this isolate formed a monophyletic group, distinct from Ceratocystis isolates and from Ophiostoma ulmi (Buisman) Nannf. The chalara-like anamorph from Juniperus is also distinct from typical Chalara anamorphs of Ceratocystis s. str. in that it produces conidia from phialides via apical wall building, in contrast to the ring wall building typical of Chalara species. We, therefore, propose the establishment of a new genus, Xenochalara gen. nov., for this and other chalara-like species producing conidia by apical wall building.