Petrakina Cif., in Petrak & Ciferri, Annls mycol. 30(3/4): 225 (1932)
Epiphytes, biotrophic or saprobic on the surface of leaves appearing as blackened spots. Superficial hyphae not observed. Sexual state: Thyriothecia superficial, scattered, central ostiole present as star-like opening. Upper wall comprising brown-walled, complexly arranged hyphae, branched at margin, poorly developed at the base. Hamathecium of septate, pseudoparaphyses, anastomosing between and above the asci, embedded in a gelatinous matrix. Asci 6–8-spored, rarely 8-spored, bitunicate, fissitunicate, clavate to broadly cylindrical, short pedicel or pedicel sometimes absent, apically rounded, ocular chamber absent. Ascospores overlapping 2-seriate, oblong to fusoid, muriform, hyaline to pale brown when immature and brown at maturity, smooth-walled. Asexual state: Unknown.
Notes: Petrakina mirabilis was introduced from Typha latifolina in Petrak and Cifferi (1932). A second species, Petrakina discoidea M.L. Farr & M.E. Palm was introduced by Farr and Palm (1985). They illustrated orbicular thyriothecia of Petrakina discoidea, opening by stellate dehiscence and presence of copious, hyaline to light brown, superficial hyphae which much more typical of Asterinaceae. Petrakina mirabilis is mostly typical of Asterinaceae, however the cells of the upper wall of the thyriothecia (meandering and several layers thick), copious pseudoparaphyses, fusiform asci and muriform ascopores are atypical. Micropeltidaceae may also need consideration, but Petrakina is also atypical of this family (Wu et al. 2011). We decided to place it in Dothidoemycetes genera incertae sedis.
Type species: Petrakina mirabilis Cif., Annls mycol. 30(3/4): 225 (1932) Fig. 45
Species