Characterisation of synnematous bark beetle-associated fungi from China, including Graphium carbonarium sp. nov.

Abstract

Ophiostomatoid fungi on trees are typically bark beetle associates that cause sapstain in timber and some are pathogens. Very little is known regarding the ophiostomatoid fungi associated with bark beetles in China and the aim of this study was to identify a collection of these fungi with synnematous anamorphs. Micromorphology and DNA sequences of the internal transcribed spacer regions (ITS) of the ribosomal DNA and the partial β-tubulin gene were used for identifications. The isolates could be divided in six morphological groups. DNA sequence comparisons with published data confirmed that these groups represented six species, four in the Ophiostomatales (Sordariomycetidae) and two in the Microascales (Hypocreomycetidae). The majority of these were isolated from conifer hosts. Ophiostoma quercus, O. setosum, Pesotum fragrans (Ophiostomatales) and Graphium pseudormiticum (Microascales) were found on Tsuga dumosa infested by a Pissodes sp. In addition, O. quercus and P. fragrans were found associated with Tomicus yunnanensis on Pinus yunnanensis, P. fragrans with a Pissodes sp. on P. armandi, and O. piceae with Ips subelongatus on Larix olgensis. Only two species, O. quercus and a new species in the Graphium penicilliodes complex, described here as Graphium carbonarium sp. nov., were isolated from Pissodes galleries on Salix babylonica. These results include several new fungus-host and fungus-insect associations, and G. pseudormiticum is reported here for the first time from China.