Sordariomycetes, Sordariomycetidae, Diaporthales, Cytosporaceae
Saprobic, parasitic on the host plant in terrestrial habitat or on mangroves in marine habitat (Sutton 1980, Norphanphoun et al. 2018, Shang et al. 2019, this study). Sexual morph: see Adams et al. (2005, 2006), Shang et al. (2019). Asexual morph: Conidiomata, dark brown to black, eustromatic, pycnidial, solitary to gregarious or confluent, globose to subglobose, conical or irregular in shape, multilocular and convoluted, thick-walled, glabrous, ostiolate; the locules radiating and enlarging from the centre, separated by conidiomatal wall, but united in the ostiolar region. Ostiole circular, erumpent, prominent, centrally located, with or without a furfuraceous ring. Conidiomatal wall composed of thick-walled, dark brown to subhyaline cells of textura angularis to textura intricata or textura oblita. Conidophores arising from innermost wall layer of locular wall, hyaline, cylindrical to subcylindrical, branched, septate, smooth-walled. Conidogenous cells hyaline, phialidic subcylindrical to lageniform, determinate, integrated or discrete, thick and smooth-walled. Conidia hyaline, allantoid, unicellular, smooth-walled, eguttulate.
Type species: Cytospora chrysosperma (Pers.) Fr., Syst. mycol. (Lundae) 2(2): 542 (1823)
Notes: Cytospora species are widely distributed around the world and occur as endophytes, saprobes or plant pathogens (Adams et al. 2005, 2006, Norphanphoun et al. 2017, 2018, Lawrence et al. 2018, Shang et al 2019). Some species can cause dieback and canker on economically important orchard crops, such as Juglans, Malus, Prunus, Punica, Vitis and Ziziphus (Wang et al. 2011, Palavouzis et al. 2015, Fan et al. 2015a, 2020, Lawrence et al. 2017, 2018, Venter et al. 2017), and ornamental plants, urban and forest trees (Adams et al. 2005, 2006, Fan et al. 2015b, 2020, Norphanphoun et al. 2017, 2018, Jami et al. 2018, Zhu et al. 2018).
Cytospora is characterized by stromatic, pycnidial, unilocular to multilocular and labyrinthine conidiomata with long necks, cylindrical, branched conidophores, usually phialidic conidogenous cells and hyaline, unicellular, allantoid conidia (Sutton 1980, this study). Ascomata are stromatic, perithecial, multilocular, globose to subglobose, with long or short necks, containing 8-spored, unitunicate, clavate, sessile asci with a J- apical ring and hyaline, allantoid, aseptate ascospores (Adams et al. 2005, Norphanphoun et al. 2018, Shang et al. 2019).
Conidia and ascospores in many Cytospora species are similar in shape and dimension, and specific morphological distinctions are limited (Adams et al. 2005, 2006, Norphanphoun et al. 2017, Fan et al. 2020). This lack of distinct morphological characters caused Cytospora taxonomy to be largely dependent on host association, leading to many of the described species being identifiable only by host. However, this reliance on host association provides a far from natural classification, as several species are not restricted to a single specific host, or a single host may have more than one Cytospora species (Norphanphoun et al. 2017, Lawrence et al. 2018, this study). Adams et al. (2002, 2005, 2006) applied molecular data to identify Cytospora species and overcome these difficulties. Approximately 650 epithets of Cytospora are listed in Index Fungorum (2019), but many are considered as synonyms of previously described taxa or treated as dubious (Kirk et al. 2008). However, more than 150 species are estimated in Cytospora (Kirk et al. 2008, Norphanphoun et al. 2017, 2018, Lawrence et al. 2017, 2018, Fan et al. 2018, Zhu et al. 2018, Fan et al. 2020). The taxonomy and nomenclature of Cytospora has been discussed in Norphanphoun et al. (2017), Lawrence et al. (2018) and Fan et al. (2010), and will not be presented here. We describe two new taxa, C. globosa and C. phialidica, from Italy based on morphology and phylogeny, and one new host record of C. prunicola. We also provide a detailed description and illustration for an unidentified Cytospora and describe and illustrate two other species (C. parasitica and C. tanatica).
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.