The genus Melanconis (Diaporthales)

Pseudocryphonectriaelaeocarpicola gen. et sp. nov. (Cryphonectriaceae, Diaporthales) causing stem blight of Elaeocarpus spp. in China

Cryphonectriaceae is a diaporthalean family containing important plant pathogens of which Cryphonectriaparasitica is the most notorious one. An emerging stem blight disease on Elaeocarpusapiculatus (Elaeocarpaceae) and E.hainanensis was observed in Guangdong Province of China recently. Typical Cryphonectria blight-like symptoms including cankers on tree barks with obvious orange conidial tendrils were observed. Forty-eight isolates were obtained from diseased tissues and conidiomata formed on the hosts E.apiculatus and E.hainanensis. These isolates were further identified based on both morphology and molecular methods using the combined sequence data of the internal transcribed spacer (ITS) region, large subunit of the nrDNA (LSU), the translation elongation factor 1-alpha (tef1) and DNA-directed RNA polymerase II second largest subunit (rpb2) genes. As a result, the fungus represents an undescribed genus and species within the family Cryphonectriaceae. Hence, Pseudocryphonectriaelaeocarpicola gen. et sp. nov. is proposed herein to represent these isolates from diseased barks of E.apiculatus and E.hainanensis. Pseudocryphonectria differs from the other genera of Cryphonectriaceae in having dimorphic conidia. Further inoculation results showed that P.elaeocarpicola is the causal agent of this emerging blight disease in China, which can quickly infect and kill the hosts E.apiculatus and E.hainanensis.

Two new species of Diaporthe (Diaporthaceae, Diaporthales) associated with tree cankers in the Netherlands

Diaporthe (Diaporthaceae, Diaporthales) is a common fungal genus inhabiting plant tissues as endophytes, pathogens and saprobes. Some species are reported from tree branches associated with canker diseases. In the present study, Diaporthe samples were collected from Alnusglutinosa, Fraxinusexcelsior and Quercusrobur in Utrecht, the Netherlands. They were identified to species based on a polyphasic approach including morphology, pure culture characters, and phylogenetic analyses of a combined matrix of partial ITS, cal, his3, tef1 and tub2 gene regions. As a result, four species (viz. Diaporthepseudoalnea sp. nov. from Alnusglutinosa, Diaporthesilvicola sp. nov. from Fraxinusexcelsior, D.foeniculacea and D.rudis from Quercusrobur) were revealed from tree branches in the Netherlands. Diaporthepseudoalnea differs from D.eres (syn. D.alnea) by its longer conidiophores. Diaporthesilvicola is distinguished from D.fraxinicola and D.fraxini-angustifoliae by larger alpha conidia.

Morphology and Phylogeny of Gnomoniopsis (Gnomoniaceae, Diaporthales) from Fagaceae Leaves in China

Gnomoniopsis (Gnomoniaceae, Diaporthales) is a well-classified genus inhabiting leaves, branches and fruits of the hosts in three plant families, namely Fagaceae, Onagraceae and Rosaceae. In the present study, eighteen Gnomoniopsis isolates were obtained from diseased leaves of Fagaceae hosts collected from Fujian, Guangdong, Hainan, Henan, Jiangxi and Shaanxi provinces in China. Morphology from the cultures and phylogeny based on the 5.8S nuclear ribosomal DNA gene with the two flanking internally transcribed spacer (ITS) regions, the translation elongation factor 1-alpha (tef1) and the beta-tubulin (tub2) genes were employed to identify these isolates. As a result, seven species were revealed, viz. Gnomoniopsis castanopsidis, G. fagacearum, G. guangdongensis, G. hainanensis, G. rossmaniae and G. silvicola spp. nov, as well as a known species G. daii. In addition, G. daii was firstly reported on the host Quercus aliena.

Micromelanconis kaihuiae gen. et sp. nov., a new diaporthalean fungus from Chinese chestnut branches in southern China

Melanconis-like fungi are distributed in several families of Diaporthales, mainly Juglanconidaceae, Melanconidaceae, Melanconiellaceae and Pseudomelanconidaceae. A new Melanconis-like genus of Pseudomelanconidaceae was discovered on branches of Chinese chestnut (Castanea mollissima) in southern China, which was confirmed by both morphology and phylogenetic analysis of combined ITS, LSU, tef1a and rpb2 sequences. The new genus Micromelanconis is characterized by two types of conidia from natural substrate and manual media of PDA, respectively. Conidia from Chinese chestnut branches are pale brown, ellipsoid, multiguttulate, aseptate with hyaline sheath. While conidia from PDA plates are pale brown, long dumbbell-shaped, narrow at the middle and wide at both ends, multiguttulate, aseptate, and also with hyaline sheath. All Pseudomelanconidaceae species were only reported on tree branches in China until now. More interesting taxa may be discovered if detailed surveys on tree-inhabiting fungi are carried out in East Asia in the future.

Mycosphaerangium and Neomelanconium (Cenangiaceae) are closest relatives: phylogenetic relationships, morphology and a new species

Based on molecular phylogenetic analyses of a multigene matrix of partial nuSSU-ITS-LSU rDNA, RPB1, RPB2 and TEF1 sequences and by morphological evidence, the genus Mycosphaerangium is shown to be the closest relative of Neomelanconium, and confirmed to be a member of the Cenangiaceae (Leotiomycetes). While Mycosphaerangium and Neomelanconium share many traits like similar conidia, conidiogenesis, asci and ascospores, their apothecia differ particularly in excipular features and are therefore recognized as distinct genera. Mycosphaerangium tiliae, described from North America, is excluded from the genus but shown to represent the sexual morph of the European Neomelanconium gelatosporum, and it is therefore synonymized with the latter. Based on morphology, Neomelanconium deightonii is assumed to be congeneric with Neomelanconium gelatosporum, and it is lectotypified. Dermatea tetraspora and Phaeangium magnisporum, the basionyms of Mycosphaerangium tetrasporum and M. magnisporum, respectively, are lectotypified as well, and for M. tetrasporum, the asexual morph is recorded for the first time. Mycosphaerangium quercinum sp. nov. is described as a new species from various Quercus hosts in Europe, where it is shown to be widely distributed. It morphologically and ecologically closely resembles the North American M. tetrasporum, but differs in paraphysis and ascospore morphology and by croziers at its ascus base. The three accepted species of Mycosphaerangium and the two of Neomelanconium are described and illustrated. Mycosphaerangium magnisporum, M. quercinum and M. tetrasporum are recorded to be constantly associated with species of Coryneum, indicating a fungicolous habit, but no evidence for fungal associations has been found in Neomelanconium deightonii and N. gelatosporum.