Peltigera scabrosella
A rare boreal Dogtooth, the Little Scabby Dogtooth, only know from single a very large mossy boulder in a ravine in Nairn, where it will be very vulnerable to loss to random events. It has lobes, which are roughened but not tomentose and with upturned margins, separating it from the Peltigera membranacea group. Below are pale veins diffuse veins with clusters of fasciculate pale rhizines. Potentially could occur in other sites but so far these have not been found. One to look out for, potentially also in snow patches, an alternative habitat in Scandinavia, as well as in ravines.
Thallus to 2.5 cm diam., closely attached; lobes short and narrow, to 25 mm broad, ± imbricate, acute, the margins ascending, involute; upper surface grey to grey-brown, roughened-scabrid; lower surface pale, veins diffuse, ochraceous, rhizines white to pale brown, slender, simple. Apothecia round, on short elongations or directly on lobe ends. Ascospores 80–95 × 3.5–4 µm. Thallus with tenuiorin, methyl gyrophorate, gyrophoric acid (C+ red), T2, T3 and two unidentified triterpenoids.
Peltigera scabrosella has pale, simple rhizines which may be in loose bundles, a pale underside and a pink-red triterpenoid on TLC plates. In the similar P. scabrosa the rhizines are fasciculate or fibrillose, soon blackened and the lower side is darkened in the centre. Potentially overlooked as the common Peltigera membranacea, but this has down turned margins and is tomentose not scabrid. The upturned margins on the lobes of P. scabrosella are likely be a good field character for spotting this species.
On mosses over moist, conglomerate rock.
Very rare. Scotland (Cawdor Wood, East Inverness-shire).
Only known from single a very large mossy boulder in a ravine in Cawdor Wood, Nairn, where it will be very vulnerable to loss to random events. Potentially could occur in other sites but so far not found. The Nordic Lichen Flora describes it as being found on steep rocks, especially where water is trickling down but also on mossy ground in alpine snow beds in Scandinavia (Vitikainen, 2007).
Britain: Data Deficient
Scotland: Priority Taxon for Biodiversity in Scotland
Cannon, P., Magain, N., Sérusiaux, E., Yahr, R., Coppins, B., Sanderson, N. & Simkin, J. (2021). Peltigerales: Peltigeraceae, including the genera Crocodia, Lobaria, Lobarina, Nephroma, Peltigera, Pseudocyphellaria, Ricasolia, Solorina and Sticta. Revisions of British and Irish Lichens 20: 1-34.
Vitikainen, O. (2007) Peltigeraceae. Nordic Lichen Flora 3: 87-90.
Text by Neil A Sanderson based on Cannon et al (2021)