Revision of the genus Thyronectria (Hypocreales) from China

Cytological studies reveal high variation in ascospore number and shape and conidia produced directly from ascospores in Morchella galilaea

Spores are important as dispersal and survival propagules in fungi. In this study we investigated the variation in number, shape, size and germination mode of ascospores in Morchella galilaea, the only species of the genus Morchella known to fruit in the autumn. Based on the observation of five samples, we first discovered significant variation in the shape and size of ascospores in Morchella. One to sixteen ascospores were found in the asci. Ascospore size correlated negatively with ascospore number, but positively with ascus size, and ascus size was positively correlated with ascospore number. We noted that ascospores, both from fresh collections and dried specimens, germinated terminally or laterally either by extended germ tubes, or via the production of conidia that were formed directly from ascospores at one, two or multiple sites. The direct formation of conidia from ascospores takes place within asci or after ascospores are discharged. Using laser confocal microscopy, we recorded the number of nuclei in ascospores and in conidia produced from ascospores. In most ascospores of M. galilaea, several nuclei were observed, as is typical of species of Morchella. However, nuclear number varied from zero to around 20 in this species, and larger ascospores harbored more nuclei. One to six nuclei were present in the conidia. Nuclear migration from ascospores to conidia was observed. Conidia forming directly from ascospores has been observed in few species of Pezizomycetes; this is the first report of the phenomenon in Morchella species. Morphological and molecular data show that conidial formation from ascospores is not found in all the specimens of this species and, hence, is not an informative taxonomic character in M. galilaea. Our data suggest that conidia produced from ascospores and successive mitosis within the ascus may contribute to asci with more than eight spores. The absence of mitosis and/or nuclear degeneration, as well as cytokinesis defect, likely results in asci with fewer than eight ascospores. This study provides new insights into the poorly understood life cycle of Morchella species and more broadly improves knowledge of conidia formation and reproductive strategies in Pezizomycetes.

Ascomycetes from the Qilian Mountains, China - Hypocreales

To investigate fungi from the Qilian Mountains in Gansu Province, ascomycetous specimens were collected and hypocrealean fungi were examined. Eighteen species belonging to six genera in the families Hypocreaceae and Nectriaceae were identified, including 11 species of Hypomyces and Trichoderma in Hypocreaceae and seven species of Nectria, Stylonectria, Thelonectria, and Thyronectria in Nectriaceae. Among them, Stylonectria qilianshanensis and Trichoderma gansuanum are new to science. DNA sequence analyses of combined ACL1, ITS, RPB2, and TEF1 regions confirmed their taxonomic placements. Morphological distinctions between the new species and their close relatives are discussed. Hypomyces tremellicola is reported for the first time in China.

Nectria-related fungi causing dieback and canker diseases in China, with Neothyronectriacitri sp. nov. described

To clarify phylogenetic relationships amongst Nectria, Neothyronectria and Thyronectria in Nectriaceae, we examined detailed morphological characters and performed phylogenetic analyses of a concatenated dataset, based on the ITS, LSU, tef1 and tub2 DNA sequences of fungal specimens in China. Four species of nectria-related fungi were identified, i.e. Nectriadematiosa, N.pseudotrichia, Neothyronectriacitri and Thyronectriapinicola. The newly described species, Neothyronectriacitri, is characterised by its ascomatal wall with bright yellow scurf, unitunicate asci, each with 4-spored and ascospores allantoid to short-cylindrical, uniseriate, muriform, hyaline to slightly yellowish-brown. This species has affinities with other one known species of Neothyronectria and can be distinguished by molecular data.

Two new species of Geejayessia (Hypocreales) from Asia as evidenced by morphology and multi-gene analyses

Two new species of Geejayessia are introduced, based on materials collected from central China. Geejayessiaclavata sp. nov. is characterised by gregarious, red brownish to dark red, oval-subglobose to globose perithecia that are formed on a basal stroma; (4-7-)8-spored cylindrical asci; ellipsoidal or rarely broadly ellipsoidal, uniseptate, smooth or finely verruculose ascospores; clavate, aseptate microconidia and absence of macroconidia. Geejayessiasinica sp. nov. is characterised by red to bright red, pyriform, subglobose to globose, perithecia on a basal stroma, collapsing laterally when dry; subcylindrical to clavate asci with a rounded apex; ellipsoidal, uniseptate ascospores; and falcate, multiseptate macroconidia with an arcuate tip. Morphological distinctions of the new species from the related fungi are discussed. This is the first report of Geejayessia from Asia.