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

= Allothyrium marcgraviae Syd., Annls mycol. 37(4/5): 393 (1939)
Type: S-F7209.

Epiphytes on the lower surface, forming extensive, 500– 600μm diam., blackened, web-like areas. Superficial hyphae 3–4μm diam., superficial, abundant, spreading over the host surface, black, branching at acute angles, appressoria not apparent. Sexual state: Thyriothecia 180–259μm diam., solitary, scattered or gregarious, superficial in hyphae, easily removed from the host surface, circular, dark brown to black, margin comprising a radiating arrangement of cells which fuse with the hyphae, opening with 20–25μm wide, star-like fissures when mature. Hamathecium comprising hyaline or brown, septate, hypha-like, pseudoparaphyses, which are constricted at the septum and separate asci. Asci 82–93×30– 41μm (x = 88×36μm, n=10), 8-spored, bitunicate, fissitunicate dehiscence not observed, clavate, oblong or widely cylindrical, with a knob-like pedicel up to 15–19μm, apically rounded, with ocular chamber when immature, not staining blue in IKI, asci vertically orientated in the thyriothecia. Ascospores 55–75×8–11μm (x = 64×10μm, n=10), fasciculate, elongate-clavate, hyaline when immature, becoming reddish brown to dark brown at maturity, 4–5- septate, highly constricted at the septum, septum bark brown in mature specimens, apical cell often larger and size of cells gradually decreasing to the basal cell, wall appears to be roughened, with mucilage. Asexual state: Unknown.

Material examined: BRAZIL, Santa Catarina, near Blumenau, on Marcgravia L. (Marcgravia schimperi) (Marcgraviaceae), collection date unknown, A. Schenck, Ex Herb. Sydow (S-F7209 type of Schenckiella marcgraviae); SPAIN, Tungurahua Province, near Baños, San Antonio, Hacienda, on leaves of Marcgravia rectiflora Tr. & Plannch, 7 June 1938, H. Sydow (S 691, holotype of Allothyrium marcgraviae Syd.); ibid. (BPI 647558, isotype of Allothyrium marcgraviae Syd.).

Fig. 1 Schenckiella marcgraviae (holotype of Schenckiella marcgraviae). a Herbarium package and specimens. b Thyriothecia on host. c Close-up of thyriothecium. d Surface view of thyriothecium. e Section through thyriothecium. Note the brown pseudoparaphyses separating the asci. f Asci with 8 ascospores, short pedicel and ocular chamber. g Brown pseudoparaphyses. h–m Asci. n–p Ascospores. Scale bars: d, g–n, p, q=20μm, e=100μm, f=50μm, o=10μm