Capnodiales » Mycosphaerellaceae

Virosphaerella

Virosphaerella Videira & Crous, in Videira et al., Stud. Mycol. 87: 377 (2017).

Index Fungorum number: IF 822705; Facesoffungi number: FoF 08568, 2 morphological species (Species Fungorum 2021), 2 species with molecular data.

Phytopathogenic, producing leaf spots or not. Ascomata amphigenous or epiphyllous, black, sub epidermal to erumpent, ovoid, globose or sub globose, apical ostiole, wall consisting of 2–3 layers of medium brown textura angularis. Asci aparaphysate, fasciculate, subsessile, subcylindrical to narrowly obovoid, straight to slightly curved, 8-spored. Ascospores bi- to tri-seriate, overlapping, hyaline, guttulate, thin walled, straight to slightly curved, fusoid, fusoid-ellipsoidal with obtuse ends, medianly 1-septate or slightly longer in the basal cell, slightly constricted at septum, widest just above the septum, or in the middle of the apical cell, tapering toward both ends, but with more prominent taper towards lower end, mucilaginous sheath visible around spore. Ascospore germination from both ends in two patterns (remaining hyaline): Type I (Crous 1998), growing parallel to the long axis of the spore, with lateral branches parallel or perpendicular to the long axis of spore, irregular in width, constricted at the median septum of the spore, slightly distorting; Type B (Crous 1998), germ tube growing parallel to the long axis of the spore, regular in width, not distorting or becoming constricted at septum. Spermatogonia, when present, amphigenous, dark brown, subepidermal to erumpent, globose to subglobose. Spermatia hyaline, smooth, rod-shaped, with obtuse ends (Adapted from Videira et al. 2017).

 

Type species: Virosphaerella pseudomarksii (Cheew., K.D. Hyde & Crous) Videira & Crous

 

Notes: Virosphaerella was introduced by Videira et al. (2017) with V. pseudomarksii as type species. Virosphaerella ascospore morphology is similar to that of Paramycosphaerella but differs by producing a discernable mucilaginous sheath around the ascospores (Cheewangkoon et al. 2008). V. pseudomarksii, previously known as M. pseudomarksii is characterized by a visible mucilaginous sheath, which is absent in germinating ascospores of M. marksii. V.  pseudomarksii resembles M. marksii (Carnegie and Keane 1994) in having asymmetrical apical ascospores cells and ascospores germination patterns. However, germinating ascospores of V. pseudomarksii is characterized by a mucilaginous sheath, which is absent in germinating ascospores of M. marksii. Also, ascospores of V. pseudomarksii is slightly longer and wider compared to those of M. marksii. Virosphaerella is currently, a distinct genus in Mycosphaerellaceae.

 

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