Gyalidea fritzei
Thallus thin, superficial or immersed, smooth, rarely cracked, white or sometimes rusty red, often disappearing, effuse. Photobiont chlorococcoid algae.
Anamorph: no information available.
Teleomorph: ascomata apothecia, 200-600 µm diam., 100-200 µm high, emergent, sessile and scattered or in small clusters. Disc persistently deeply concave, almost perithecioid when young, pale orange to dark brown. True exciple well-developed, markedly fuscous brown to almost black, sometimes fissured. Epithecium pale green-brown. Hymenium (80-) 120-160 μm tall, pale brown above. Hypothecium very pale brown. Interascal tissue of abundate septate simple paraphyses 1-1.5 µm diam., within a gelatinous matrix. Asci (76-) 100-120 × (25-) 30-45 μm, clavate, thin-walled except for a slightly thickened apical tholus, K/I negative, with a ± small ocular chamber, 4- to 8-spored. Ascospores (18-) 24-35 (-43) × (10-) 12-16 (-21) μm, ellipsoidal, sometimes subglobose or attenuated at one end, muriform with 5-7 transverse septa and 2-3 longitudinal divisions, the septation irregular and the individual cells sometimes nearly globose, hyaline, smooth, without an epispore, gelatinous sheath or appendages.
Assessed by Woods & Coppins (2012) as Near Threatened. It is listed as Nationally Rare, and is a Priority Taxon for Biodiversity in Scotland. It is inconspicuous and therefore likely to be overlooked.
Resembles Gyalidea lecideopsis, which occurs on dry limestones and has the upper part of the hymenium darker. A specimen with apothecia with a regular, deeply fissured margin, and smaller, muriform spores, 16-18 × 7-9 μm, collected on galena in mid-Wales, may be a new species closely related to G. fritzei.
Rare but widespread in western and northern Britain, also in northern Ireland. BLS map here.
On somewhat basic rocks and pebbles, e.g. basalt and mica-schist in upland areas, often in seepage tracks and spasmodically wet situations. Sometimes on metalliferous ores.