Muellerella lichenicola  

Anamorph: conidiomata pycnidial, ca 50 µm diam., immersed in the host thallus with the ostiole slightly protruding, the wall dark brown and composed of angular cells, lined with small ± isodiametric cells subtending the conidiogenous cells. Conidiogenous cells 4-5.5 x ca 3 µm, conical to doliiform, the apical part slightly attenuated, proliferating percurrently with inconspicuous periclinal thickening, collarettes not visible. Conidia 3-3.5 x 1-1.5 µm, bacillar to ellipsoidal, hyaline, thin-walled, without a gelatinous sheath or appendages.
Teleomorph: ascomata perithecia, 80-130 µm diam., ± globose, the ostiole distinctly papillate, black, composed of an outer laer of dark brown thick-walled isodiametirc cells 5-10 µm diam. and a less strongly developed compressed inner layer. Interascal tissue absent, the ostiole lined with hyaline periphyses to ca 15 µm in length.  Asci 63-70 x 20-26 µm, ellipsoidal to clavate, ± sessile, the apex rounded, thick-walled and sometimes with a broad ocular chamber but without distinct wall layers, probably with rostrate dehiscence, containing between 64 and ca 100 spores. Ascospores 5.5-6.5 (-7) x 3-3.5 µm [5-6 x 2.5-3 µm fide Triebel 1989], ellipsoidal to ovoid-ellipsoidal, with a single median non-constricted septum, dark brown, fairly thick-walled, smooth, without a perispore or gelatinous sheath/appendages.