Keissleriella fusispora, Keissleriella fusispora
Anamorph: not known.
Teleomorph: ascostromata perithecial, ca 150 µm diam., globose, dark brown, immersed in the substratum with only the papillate ostiolar region protruding. Ostiole surrounded by dark brown thick-walled aseptate erect or convergent setae 43-52 x 3-4.5 µm in size, the apices acute. Peridium composed of several layers of thin-walled angular and flattened cells, the outer layers with darker and thicker walls and surrounded by a weakly developed tomentum of brown and sometimes verrucose hyphae. Interascal tissue of copious cellular thin-walled pseudoparaphyses 1.5-2 µm diam. Asci 64-83 x 7.5-9.5 µm [55-85 x 7.5-10.5 µm fide Scheuer 1988], cylindric-clavate, short-stalked, thick-walled and fissitunicate, 8-spored. Ascospores arranged biseriately, 15.5-19.5 x 3-4 µm [18-24 x 3-4 µm fide Scheuer 1988], fusiform, not curved, at maturity hyaline and 3-septate [1-septate fide Scheuer 1988], constricted at the median (primary) septum and with the cell immediately above distinctly swollen, degenerating spores sometimes becoming pale brown, with a thin mucous sheath.
Not formally assessed. Known only from a single collection from GB&I, but the species is very inconspicuous and could be overlooked.
Differs from K. culmifida primarily by its narrower ascospores, but the original collections from Austria have 1-septate spores rather than the 3-septate ones seen here. The two may not be conspecific.
Immersed in dead leaves of Carex binervis, presumably as a saprobe.
In GB&I, only known from Hoy (Orkney Is, Scotland). Originally described from the eastern Alps.