Graphis handelii
Draft
Similar to Graphis scripta (i.e. with non-striate lirellae), but the thallus has a K+ yellow→red (crystals) reaction (as with G. elegans), and the hymenium is inspersed with oil droplets and ± exposed in mature ascomata. Mature ascospores of British material measure 25–45 × 7–9 μm and are 6- to 9-septate, smaller poorly formed spores also typically occur, the smallest measured being 17 x 6µm and 5 septate.
A pantropical species but recently reported from Portugal (there with rather smaller ascospores; illustrated by Lepista & Aptroot 2016) and now west Ireland and S. England. Potentially overlooked for G. scripta s. lat., or for apparently young specimens of G. elegans. The lirellae of G. handelii often partially fall out, with new lirellae regenerating in the scar; this can give the impression of striate lirellae as found in G. elegans. Graphis crebra is similar but has pruinose hymenia and has been recorded in Devon.
So far recorded from Hazel, Beech and Holly in southern old growth oceanic woodlands, potential more widespread.
First collected from Hazel in Atlantic Hazel wood in the Burren, Clare in 2009, but identified only recently. In 2021, also found on the acid bark of older Holly and Beech in the New Forest in old-growth woodlands (S. Hampshire).
Not evaluated, but probably at least a Notable species, potentially a Red List 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)