Sticta canariensis
Thallus of green algal morph 1-5 (-15) cm diam., often forming extensive patches. Lobes to 10 mm diam., elongate and dichotomously branched, discrete or overlapping, apices ± truncate, bright green when wet, ± shiny, smooth, often with a median channel. Lower surface flat to somewhat ribbed, whitish to red-brown, ± darkening to black-brown towards centre, ± uniformly felted-tomentose with small, scattered, rounded, white cyphellae 300-600 µmm diam. Composite thalli of the cyanobacterial and green morphs occur together, easily distinguished when wet as contrasting bright green leaflets arising from dark blue-black, lobed thalli.
Thallus of cyanobacterial morph 1-5 cm diam., often forming extensive colonies. Lobes to 20 mm diam., overlapping, margins rounded, irregularly incised, very thin and wrinkled, ± minutely dissected into small, terete or often flattened, branched isidia to 500 µm diam., often aggregated. into dense clusters, 0.2-1 mm diam., occasionally becoming densely imbricate and covering the entire surface of older parts of the thallus. Upper surface pale grey to dark grey-brown, matt, sometimes white-marbled. Lower
surface finely white-tomentose, pale brown-white, ± reticulately ridged, with white, scattered cyphellae.
Anamorph: conidiomata only associated with the green algal morph; pycnidia, flat or slightly elevated, with a dark brown apex. Conidia 5-7 μm long, straight, both ends slightly swollen.
Teleomorph: ascomata only associated with the green algal morph; apothecia, rarely developed; disc to 7 mm diam., red-brown. Thalline exciple paler, entire or crenulate, of small, ± rounded cells with ± uniformly thickened, hyaline walls. Epithecium red-brown, K–, conglutinated. Hypothecium dense, pale grey-brown, not clearing in K. Interascal tissue of simple paraphyses ca 3 μm diam., not swollen at the apex. Ascospores (20-)23-28(-32) × 6-7(-8) μm, 1(-3)-septate, hyaline.
The species was assessed as of Least Concern by Woods & Coppins (2012), but a separate assessment of the green algal morph alone concluded that it was Vulnerable (D2). It is protected under the Nature Conservation (Scotland) Act 2004 and the NERC Act 2006, and the UK has International Responsibility for the species.
The green algal morph is unmistakeable. The cyanobacterial morph could be confused with Sticta sylvatica, but differs in the dissected thallus margin fringed with flattened isidia.
The cyanobacterial morph is host to Corticiruptor abeloneae (with pale apothecia) and Hemigrapha atlantica (with black apothecia).
The species has a hyper-oceanic distribution centred on western Scotland and north Wales, with outlying populations in SW Scotland, Cumbria, central Wales, Devon and Cornwall. It is fairly widley distributed in oceanic areas of Ireland. BLS map here.
Amongst mosses on trees and rocks in perpetually moist, very sheltered, deeply shaded sites, often under a canopy of herbaceous vegetation, e.g. Pteridium.