Phaeographis inusta
Distinct from Phaeographis dendritica and P. smithii in the brown and K– thallus. The apothecia are typical branched and stellate and radiate out from a central point. P. lyellii shares a brown and K– thallus but this is waxier and the apothecia are arranged in parallel and are less branched and stellate. P. inusta is locally frequent in oceanic woods to the south west in some areas but rare in others.
Thallus thin, glossy or matt, pale grey to pale yellowish-brown, sometimes with an olivaceous tinge when fresh. Apothecia grey-black, matt, 0.1–0.25 mm wide, arthonioid, stellate, immersed with an indistinct thalline margin; true exciple thin, entire, lateral walls 12–15 µm thick broadening to 25 µm above; hymenium 45–75 µm tall. Ascospores 16–25 × 7–9 µm, 3- to 5-septate. No lichen products detected by TLC.
The apothecia lack a white thalline rim and are usually more stellate than P. lyellii. The shorter, 3- to 5-septate ascospores separate P. inusta from specimens of P. dendritica or P. smithii giving poor K and Pd reactions. Similarly from Graphis scripta s. lat., which also has somewhat narrower lirellae with a slit-like disc.
On deciduous trees, especially Hazel generally and Alder in Wales, in well-established woods; locally frequent but absent or rare in other areas. Appears to be spreading in lowland England into abandoned coppices as the Hazel bushes age.
Southern England, W. Wales, rare and localised in W. Ireland, recently recorded in N.W. England (Westmorland).
A strongly south western species occurring with very variable frequency, possibly most frequent where past coppicing intensity was lower, but apparently actively colonising into woods in new areas where coppicing has declined. Included in the Southern Oceanic Woodland Indicator list.
Britain: Notable & International Responsibility Species
Aptroot, A., Weerakoon, G., Cannon, P., Coppins, B., Sanderson, N. & Simkin, J. (2023). Ostropales: Graphidaceae, including the genera Allographa, Clandestinotrema, Crutarndina, Diploschistes, Fissurina, Graphis, Leucodecton, Phaeographis, Schizotrema, Thelotrema and Topeliopsis. Revisions of British and Irish Lichens 36: 1-23.
Text by Neil A Sanderson based on Aptroot et al (2023)