Gyalidea roseola
Thallus crustose, thin, smooth or uneven-scurfy, not gelatinous when hydrated, effuse, white to pinkish (sometimes brown due to overlying algae). Prothallus absent. Photobiont Trentepohlia.
Anamorph: no information available.
Teleomorph: ascomata apothecia, 300-700 µm diam., shallowly urceolate, superficial and sessile, or partially immersed. Disc cream to pinkish or yellowish brown, concave, appearing translucent when wet. True exciple well-developed, elevated, smooth, slightly darker or concolorous with the disc. Hymenium 90-120 μm tall, colourless, without a pigmented epithecium. Interascal tissue of abundate septate simple paraphyses 1-1.5 µm diam., within a gelatinous matrix. Asci 70-100 × 15-25 μm, clavate, thin-walled except for a slightly thickened apical tholus, K/I negative, with a ± small ocular chamber, 8-spored. Ascospores (20-)29-34(-36) × (8-)12-14 μm, ellipsoidal, the apices obtuse, muriform with 3-5 transverse septa and 8-10-cells, the septa ± constricted, hyaline, with a thin perispore.
Chemistry: no lichen products recorded.
Assessed as Critically Endangered (B, D) by Woods & Coppins (2012). It was considered to be extinct in the British Isles by Gilbert et al. (2009), but was rediscovered in 2005 at a single site in the Southern Uplands in VC72, and at a further locality in Argyll in 2010. Further searches in 2017 confirmed that the species was still present at the site in VC72, and a new site a short distance away in VC77 was discovered.
The species is unusual in having apothecia with a pale rather than dark exciple, and in the association with a Trentepohlia photobiont (Thüs et al. 2009).
Reported from single sites in VC72 Dumfriess-shire, VC77 Lanarkshire, VC97 W Inverness and VC98 Argyll.
On shaded limestone or micaceous sandstone rocks in old lead mine workings.