Taxonomy and Phylogeny of Ascomycetes with Emphasis on Hypocrealean Entomopathogens from China and Thailand

Abstract

Ascomycetes historically being used to accommodate a group of fungi that sexually reproduce via ascospores where these ascospores are formed in a ‘sac-like’ structure called an ascus. Many species in ascomycetes have apparently lost the ability to form the sexual stages and were classified as hyphomycetes or coelomycetes based on their asexual reproduction. However, with the aid of modern techniques such as molecular data analyses, these ascomycetes, hyphomycetes and coelomycetes were linked in different taxonomic ranks. Documentation of known and novel ascomycetes based on fresh collections accompanying with polyphasic approaches is essential for understanding their natural classification. Ascomycetes often live as parasites/pathogens, endophytes and saprobes, exploring hosts spanning three life kingdoms (animal, fungi and plant). Investigation of ascomycetes in China and Thailand during 2018 to 2022 have resulted in the discovery of 43 arthropod-pathogenic fungi, three fungicolous fungi, 11 lignicolous saprobes and one plant symbiotic fungus. Majority of arthropod-pathogenic fungi taxonomically concentrate in Hypocreales (Sodariomycetes, Ascomycota). In this study, morphology-phylogeny analyses have revealed six new entomopathogenic species, viz. Hirsutella hongheensis, Ophiocordyceps tianshanensis, Paraisaria alba, P. arcta, P. rosea, Simplicillium formicae; four new sexual/host/geographic records, viz. Beauveria majiangensis, Lecanicillium uredinophilum, Ophiocordyceps globiceps, O. vespulae; 33 reference species viz. Akanthomyces kanyawimiae, A. samoensis, Beauveria bassiana, B. medogensis, B. pseudobassiana, Blackwellomyces roseostromatus, Cordyceps cateniobliqua, C. cateniannulata, C. cicadae, C. fumosorosea, C. inthanonensis, C. neopruinosa, C. qingchengensis, C. pruinosa, C. rosea, C. tenuipes, Gibellula gamsii, Metarhizium pemphigi, M. purpureonigrum, Moelleriella chiangmaiensis, M. raciborskii, Nomuraea rileyi, Ophiocordyceps blattae, O. camponoti-leonardi, O. crinalis, O. irangiensis, O. nutans, O. pseudolloydii, O. sporangifera, O. thanathonensis, Orbiocrella petchii, Purpureocillium takamizusanense and Samsoniella hepialid. A website called invertebratefungi.org dedicated to the fungi on invertebrates was established. It focuses on providing an up-to-date classification of invertebrate fungi with notes on genera and species, keeping abreast of the current literature. Hypocrealean entomopathogenic taxa explore various arthropods and present highly diverse phenotypes. The distribution and evolutionary relationships of fungal, arthropod, microinvertebrate and plant associated fungi within clavicipitoids were studied based on ancestral character state analysis. Specific morphological features (such as stromal form, perithecia arrangement, ascospores, secondary spore and conidiophore structures) were exmined if they are phylogenetically informative. Fungicolous fungi associated with arthropod-pathogens inadvertently appear in our visual fields during the survey of entomoapthogenic fungi. DNA-based phylogeny and morphological analyses have revealed two hyperparasites viz. Pleurocordyceps ophiocordycipiticola sp. nov (on Ophiocordyceps cylindrica) and Simplicillium lanosoniveum (on Ophiocordyceps unilateralis) and one Elaphomyces-infecting fungus, Perennicordyceps elaphomyceticola. Lignicolous saprobes are a major part of microfungi, serving as an excellent decomposer of dead wood. In this thesis, seven new saprobic taxa are introduced based on multi-loci phylogeny and morphological observation, which including two new genera (Camporesiomyces and Neohormodochis) and five new species (i. e. Camporesiomyces mali, Fitzroyomyces hyaloseptisporus, Neohormodochis septispora, Phacidiella kunmingensis and Pseudochaetosphaeronema kunmingense). Six known species occurring on dead twig are identified and they are Astrocystis bambusicola, Apiospora guiyangensis, Discosia pini, Ostropomyces pruinosellus, O. thailandicus and Sarocladium kiliense. Epichloë sylvatica is an endophytes associated with Microstegium sp. (Poaceae).