Schenckiella Henn., Bot. Jb. 17: 523 (1893).

Allothyrium Syd., Annls mycol. 37(4/5): 393 (1939)

Epiphytes, forming blackened, web-like areas. Superficial hyphae abundant, black, branching at acute angles, appressoria not apparent. Sexual state: Thyriothecia solitary, scattered or gregarious, superficial in hyphae, easily removed from the host surface, circular, dark brown to black, opening with starlike fissures. Hamathecium comprising hyaline or brown, septate, hypha-like, pseudoparaphyses, constricted at the septum and separate asci. Asci 8-spored, bitunicate, fissitunicate, clavate, oblong or widely cylindrical, with a knob-like pedicel, apically rounded, with ocular chamber, not staining blue in IKI, asci vertically orientated in the thyriothecia. Ascospores fasciculate, elongate-clavate, hyaline when immature, becoming reddish-brown to dark brown at maturity, trans-septate, strongly constricted at the septum, apical cell larger and size of cells gradually decreasing to the basal cell. Asexual state: Unknown.

Notes: Schenckiella was introduced by Hennings (in Bot. Jb. of Engler 1893) and has remained monotypic and is represented by Schenckiella marcgraviae Henn. Allothyrium was introduced by Sydow (1939) and is represented by A. marcgraviae Syd. and has remained monotypic until now and is identical to Schenckiella marcgraviae and is thus a synonym. This is a very unusual genus with a unique combination of characters, with nonappressoriate surface hyphae, Asterina-like thyriothecia, elongated clavate asci, brown pseudoparaphyses, which are rarely observed in the Dothideomycetes, and 4–5-septate brown ascospores. Schenckiella only appears to occur on leaves of Marcgravia, a genus in the family Marcgraviaceae, native to the Caribbean Islands, Central America, and South America. Schenckiella also typical with Parasterinopsis with ascospores, but just differs in lacking appressoria, thus it is unclear how this fungus feeds on the host. Future study is needed, and collections should be made on this host family to establish if the genus is monotypic.

Type: Schenckiella marcgraviae Henn., Bot. Jb. 17: 523 (1893)