Pyrenula laevigata


Pyrenula laevigata

(Pers.) Arnold (1885)
Conservation Status
LC NS Sc IR (Key)
BLS Number
Taxon Photo
General Description

A characteristic Pyrenula of smooth bark communities in temperate rainforest habitats. Distinguished by the silvery or cream to pale yellow-brown thallus lacking pseudocyphellae, with prominent black pycnidia, which characteristically for lines along the edge of the thallus where it meets another thallus of the same species. Mycomicrothelia confusa can look similar and is also found in oceanic woodland, but lacks the distinctive pycnidia in lines. Locally abundant in western Scotland and in parts of western Ireland, but rare in the west beyond and very local in western Ireland.


Thallus immersed, silvery or cream to pale yellow-brown; pseudocyphellae absent. Perithecia 0.45–0.66 mm diam., forming projections in the thallus, somewhat flattened in section, with an involucrellum separable from the exciple and spreading somewhat; hymenium not containing anthraquinones, K–. Ascospores (14–) 17–22 (– 26) × (7–) 8–9 (–11) μm, 3-septate. Pycnidia black, to ca 100 μm diam., scattered or in lines; conidia 10–19 × ca 0.5 μm, curved. Thallus C–, K+ yellow, KC–, Pd–, UV–.

The status of this taxon in Britain and Ireland deserves closer study as it is primarily continental in distribution. A K+ fleeting blue reaction has been reported in the hymenium of this species, but has not been detected in British or Irish material. Mycomicrothelia confusa can look similar and is also found in oceanic woodland, but lacks the distinctive pycnidia in lines and has very different spores, see also P. occidentalis.


On smooth bark, especially of Hazel, in oceanic woodlands and characteristic of temperate rainforests.

Distribution Map
Key to map date classes

Local, rare in S.W. England (N. Devon), N. Wales (Cardigan, Merioneth) and N.W. England, abundant in W. Scotland, and very patchy in W. Ireland. 

Threats & Status

A characteristic and constant species of undescribed hyperoceanic Graphidion communities confined to temperate rainforest habitats. The lichen has very strong populations in the western Highlands and isles, but rare and threatened beyond in Britain. 

Britain: Notable, International Responsibility species

Scotland: Priority Taxon for Biodiversity in Scotland 

Wales: Vulnerable


Cannon, P., Coppins, B., Aptroot, A., Sanderson, A. & Simkin, J. (2023). Perithecial genera I, including Acrocordia, Alloarthopyrenia, Anisomeridium, Antennulariella, Arthopyrenia, Celothelium, Cyrtidula, Dichoporis, Eopyrenula, Julella, Leptorhaphis, Leptosillia, Lithothelium, Mycomicrothelia, Mycoporum, Naetrocymbe, Pyrenula, Rhaphidicyrtis, Sarcopyrenia, Swinscowia and Tomasellia. Revisions of British and Irish Lichens 37: 1-59.

Text by Neil A Sanderson