Pyrenula macrospora

Pyrenula macrospora
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Eurotiomycetes
Order:	Pyrenulales
Family:	Pyrenulaceae
Genus:	Pyrenula
Species:	P. macrospora
Binomial name
Pyrenula macrospora (Degel.) Coppins & P.James (1980)
Synonyms [1]
Pyrenula nitida var. macrosporaDegel. (1941) Pyrenula chlorospila var. macrospora(Degel.) Maas Geest. (1958)

Pyrenula macrospora is a species of corticolous (bark-dwelling crustose lichen in the family Pyrenulaceae. ^[2] The lichen has a smooth olive-brown to fawn thallus marked with small white spots, and produces curved ascospores within convex fruiting bodies. It grows on the smooth bark of deciduous trees in oceanic climates, where it is found mainly in western coastal regions of Europe, Asia, and Macaronesia.

Taxonomy

The species was originally described by Gunnar Degelius in 1941 as Pyrenula nitida var. macrospora. ^[3] Rudolf Arnold Maas Geesteranus thought that the taxon was more appropriately classified as a variety of Pyrenula chlorospila . In 1980, Brian John Coppins and Peter Wilfred James raised it to full species status. ^[4]

Description

The thallus (the main body of the lichen) is olivaceous to fawn or dark brown, and typically has a smooth surface, including around the perithecia. White pseudocyphellae are present, measuring about 40–120  μm in diameter. ^[5]

Perithecia measure mainly 0.5–0.9 mm across (occasionally as small as 0.4 mm or as large as 1.2 mm) and form convex projections. The exciple contains numerous colourless crystals, and the hymenium lacks anthraquinones. Ascospores are 3-septate and measure mostly 27–33 × 10–13 μm (overall range 24–36 × 8–13 μm). Pycnidia are frequent and appear as dark dots about 100–180 μm in diameter, usually most evident on younger parts of the thallus and often clustered along boundaries between adjacent thalli. Conidia are curved, measuring 10–16 × about 0.8 μm. Spot tests are C–, K+ (yellow), KC–, and Pd+ (faintly yellow); under ultraviolet light the thallus shows a weak yellow fluorescence that may be absent, attributed to an unidentified substance. ^[5]

Habitat and distribution

Pyrenula macrospora occurs in temperate areas of the Old World. ^[6] It has a strongly oceanic distribution, and has been recorded from Asia, Europe, and Macaronesia. It grows on the smooth bark of deciduous trees. ^[5] In Britain, Pyrenula macrospora has been treated as an "oceanic-widespread" lichen, a biogeographic pattern associated with Atlantic-influenced climates and characterised by concentrations along the western seaboard and relative scarcity away from the Atlantic coast. ^[7]

A bioclimatic-envelope modelling study based on British records (1960–2006) linked the species' predicted occurrence mainly to winter temperature and winter precipitation. Under UKCIP02 (the UK Climate Impacts Programme's 2002 climate-change scenarios) projections for the 2050s, the same study projected an increase in climatically suitable area for P. macrospora, including a possible expansion into more easterly parts of Britain. ^[7]

See also

• List of Pyrenula species

References

1. "GSD Species Synonymy. Current Name: Pyrenula macrospora (Degel.) Coppins & P. James, in Hawksworth, James & Coppins, Lichenologist 12(1): 107 (1980)". Species Fungorum . Retrieved 19 December 2025.
2. "Pyrenula macrospora (Degel.) Coppins & P. James". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved 19 December 2025.
3. Degelius, G. (1941). "Lichens from the Azores, mainly collected by Dr. H. Persson". Göteborgs Kungliche Vetenskaps- och Vitterhets Samhälles Handlingar. 6B. 1 (7): 1–46 [8].
4. Hawksworth, D. L.; James, P. W.; Coppins, B. J. (1980). "Checklist of British lichen-forming, lichenicolous and allied fungi". The Lichenologist. 12 (1): 1–115 [107]. doi:10.1017/S0024282980000035.
5. 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 (PDF). Revisions of British and Irish Lichens. Vol. 37. p. 33.
6. Aptroot, André (2012). "A world key to the species of Anthracothecium and Pyrenula". The Lichenologist. 44 (1): 5–53 [31]. doi:10.1017/S0024282911000624.
7. Ellis, Christopher J.; Coppins, Brian J.; Dawson, Terence P.; Seaward, Mark R.D. (2007). "Response of British lichens to climate change scenarios: Trends and uncertainties in the projected impact for contrasting biogeographic groups". Biological Conservation. 140 (3–4): 217–235. doi:10.1016/j.biocon.2007.08.016.