Pyrenula chlorospila
Thallus crustose, olive-green to pale brown or fawn, immersed, smooth, not areolate. Pseudocyphellae 40-120 μm diam., white, rather variably developed. Photobiont Trentepohlia.
Anamorph: no information available.
Teleomorph: ascomata perithecia, small, 200-400 µm diam., often rather densely arranged, forming very low projections in the thallus or hardly protruding. Involucrellum developed around and closely adhering to the exciple, not clearly distinct, composed of filamentous hyphae interspersed with bark cells and often crystals. Ostiole central. Exciple containing hyaline calcium oxalate crystals. Hymenium not inspersed with droplets, without anthraquinones. Interascal tissue composed of very narrow branched and anastomosed hyphae, the ostiole lined with periphyses. Asci cylindrical, long-stalked, multilayered in structure, the apex thickened, with an internal apical beak and a refractive subapical cap, I–, K/I–, fissitunicate, 8-spored. Ascospores (25-) 28-32 (-35) × (9-) 11-13 (-14) μm, broadly fusiform, the apices obtuse, with three transverse distosepta, the cell lumina appearing lenticular to angular, smooth, without anepispore, gelatinous sheath or appendages.
Chemistry: thallus C–, K+ yellow, KC–, Pd+ faintly yellow, UV± whitish (unidentified substance).
Assessed by Woods & Coppins (2012) as of Least Concern.
Throughout southern and western Britain, also common in Ireland. BLS map here.
On smooth, shaded bark of deciduous trees, often associateed with Pyrenula macrospora; locally abundant.