Stigmidium fuscatae (Arnold) R. Sant.

Non-lichenized lichenicolous fungus.

     Perithecioid ascomata globose, 0.20-0.50 mm in diameter, raised and as if resting on the thallus of the host (which differentiates it from the submerged apothecia of this host), black, often abundant (giving a domino appearance !). Utriform asci with 4 or 8 spores. Ascospores hyaline, broadly elliptical, with rounded ends, 1=septate and giving two cells of unequal size often with a large vacuole in the center, 10-12 x 4-5 µm according to the literature, 10-13 x 4-5 µm according to our measurements. Parasitic of the thalli of Acarospora fuscata, rare (or passing unnoticed because it is moderately aggressive).