Calicium pinastri
This lichen forms a thin grey thallus on Pinus bark with tiny epruinose black stalked apothecia 0.3–0.4mm high. The size of the cylindrical asci with uniseriately arranged spores is diagnostic at 30–35 x 4–5μm. This separates the species from stunted epruinose specimens of Calicium glaucellum, which has similar but longer and slightly narrower asci that are 35–41 x 3.3–4.5μm. A pine bark specialist, rarely recorded from lignum, first found in 2018 in native pinewood in Speyside and on introduced Scots Pine colonising glades in ancient Beech dominated pasture woodland in the New Forest. Also recorded from Oak lignum in the New Forest. Likely to occur elsewhere in Britain. See Peksa (2006).
Thallus very thin, grey and sometimes with a greenish tinge, or ± immersed. Apothecia (0.2–) 0.33-0.4 mm, 2–3 times as high as the width of the stalk, not pruinose, I–; head 0.14–0.2 mm diam., obconical to lenticular, with a flat or slightly convex upper surface. Stalk often rather short, glossy black, not pruinose, 0.09–0.15 mm diam., consisting of dark brown interwoven strongly sclerotized hyphae, the surface layer paler and forming a ± distinct colourless coat. Asci when mature cylindrical with uniseriately arranged spores, 30–35 × 3.7-5.4 µm. Ascospores when young smooth, when mature with an ornamentation of irregular cracks, broadly ellipsoidal, 9.5-13.5 × 5.1–6.4 µm. Thallus C–, K–, KC–, Pd–.
Close to Calicium glaucellum, but the apothecia lack pruina at the edge of the exciple, the ascospores have an ornamentation of irregular cracks rather than minute longitudinal ridges, and the asci are shorter and relatively broader. Calicium parvum, is also found on Pine bark, but has a verrucose thallus and clavate asci.
On bark of Scots Pine, recorded once on Oak lignum. Found in both old growth native pinewoods and on introduced younger Pines where the truncks are better lit. Peksa (2006) describes C. pinastri to be more tolerant to desiccation of habitats, and occurring often in more open sites, compared to Calicium parvum.
England (Hampshire, New Forest) and Scotland (Moray, East Ross & Cromarty); rarely recorded but probably overlooked and potentially widespread.
Difficult to assess but the data in Peksa (2006) suggest it is likley to be less threatened than Calicium parvum.
Cannon, P., Prieto, M., Coppins, B., Sanderson, N., Scheidegger, C. & Simkin, J. (2021). Caliciales: Caliciaceae, including the genera Acolium, Amandinea, Buellia Calicium Diploicia, Diplotomma, Endohyalina, Monerolechia, Orcularia, Pseudothelomma, Rinodina and Tetramelas. Revisions of British and Irish Lichens 15: 1-35.
Peksa, O. (2006) Calicium parvum (Caliciaceae) – a new calicioid lichen to the Czech Republic. Silva Gabreta 12: 51-56 Link
Text by Neil A Sanderson, based Cannon et al (2021)