Taxonomic And Ecological Studies On Rock-inhabiting Fungi In China

Rock-inhabiting fungi (RIF) are mostly slow-growing, melanised and meristematic fungi which tolerate wide ranges of stresses, such as high fluctuations in temperature, low water activity, solar irradiations, and low nutrient availability. Rock-inhabiting fungi (RIF) are peculiar organisms that can survive in hostile conditions by adaptations including melanisation that protects cells against UV radiations, the typical isodiametrical (meristematic) growth form that ensures an optimal volume surface ratio to enhances their survival, and oligotrophic features that aids them to grow on sparse, airborne nutrients available on rock surfaces. Some of RIF produce internal asexual spores that allow them to save energy and form microcolonies to protect them from harsh habitats. RIF have often been overlooked due to their tiny necrosis in nature, slow growth and the lack of diagnostic features. The development of a molecular phylogeny provides an essential tool for the identification and taxonomy of these fungi. In the past two decades, RIF have started to attract the attention of mycologists and many new taxa have been found and described. However, there are a few investigations on RIF in China. In this study, we investigate RIF in China and a number of RIF have been isolated and identified.1. Rock sample collection and RIF isolation. Three hundred and forty-eight rock samples were collected from Qinghai-Tibetan plateau including Shigatse, Nyingchi and Qamdo, and Sichuan, Yunnan, Guangxi, Jiangxi, Anhui, Henan, Hebei and Beijing. Total1215fungi were isolated. After identification,85dry specimens and339slides were deposited in Herbarium Mycologicum, Academia Sinica. Total81species belonging to21genera and747isolates were identified by the multigene sequence analysed coupled with morphological characteristics. Three new genera Rupestriomyces, Spissiomyces and Anthracina, and39new species were discovered in this study.2. Taxonomy of RIF in Dothideomycetes. Phylogenic analysis revealed that two new genera, Rupestriomyces and Spissiomyces affiliated in incertae sedis, Dothideomycetes, were described. The RIF in this group of fungi belong to11genera, e.g. Catenulostroma, Cladosporium, Coniosporium, Cryomyces, Devriesia, Elasticomyces, Oleoguttula, Phaeothecoidea, Rachicladosporium, Rupestriomyces and Spissiomyces. There are19new species in Dothideomycetes, e.g. Catenulostroma spissicolonia, C. catenulata, Coniosporium globulosa, C. crassiparies, C. aridis, C. gemmiformis, C. meristema, Devriesia catenata, D. separata, D. intermedia, Oleoguttula nagquisa, Phaeothecoidea endoconidia, Rupestriomyces sinensis, R. ampulliformis, R. torulosus, Spissiomyces aggregates, S. ramosus and S. globosu. The detailed morphological characteristics and phylogenic position have been described and discussed for each species.3. Taxonomy of RIF in Eurotiomycetes. The most of RIF in Eurotiomycetes are in Trichomeriaceae. We confirmed that Trichomeriaceae is a family in Chaetothyriales according to the phylogenetic tree based on18S,28S and mtSSU sequences. A new genus Anthracina was identified and in Trichomeriaceae (Eurotiomycetes, Chaetothyriales). The genera Anthracina, Bradymyces, Knufia and Trichomerium are similar in morphology but are well distinguished from phylogenetic tree based on28S,18S, mtSSU, ITS, TEF1, RPB1and TUB sequences. The RIF in this group of fungi belong to6genera, e.g. Anthracina, Bradymyces, Cladophialophora, Exophiala, Knufia and Trichomerium. Twenty new species in Eurotiomycetes are also described including Anthracina ramosa, A. saxincola, Bradymyces catenulatus, B. circinatus, B. pullus, B. yunnanensis, Cladophialophora catenata, C. ellipsoidea, C. volcanic, C. aggregata, Exophiala ellipsoidea, E. indurata, E. clavispora, E. gemmipara, E. multa, Knufia gemmata, K. calcarecola, K. separate, Trichomerium lapideum and T. cicatrices. The detailed morphological characteristics and phylogenic position have been described and discussed for each species.4. Frequency and distribution for RIF. The dominant genus was Knufia and the common genera were Bradymyces, Catenulostroma, Coniosporium, Cladophialophora, Devriesia, Exophiala, Knufia, Rupestriomyces and Spissiomyces in identified isolates. The dominant species were Knufia sp.(8.7%), Catenulostroma catenulata (5.4%) and Bradymyces pullus (4.2%). The dominant species are varied in different regions such as there are Knufia sp.(6.7%), Bradymyces pullus (4.2%) and Exophiala opportunistic (4.1%) in Qinghai-Tibetan plateau, while there are Catenulostroma catenulate (5.4%), Rupestriomyces torulosus (4.0%), Trichomerium lapideum (3.8%) in the Eastern China. This study revealed a high diversity of RIF. More studies on investigation, systematics and ecology of RIF should be further conducted to improve our understanding on this group of fungi.