Peltigera praetextata
A large impressive Dogtooth, the Childing Dogtooth, similar to Peltigera membranacea with wide thallus lobes which are tomentose on the top surface. Differs in the numerous scale-like, mainly marginal, schizidia on the upper surface of the thallus which is also less strongly bullate-ridged compared to P. membranacea. Common in sheltered situations in most of Britain and Ireland, but rather rare in the drier or deforested lowland areas
Thallus to 20 (–30) cm diam.; lobes 1–1.5 (–2) cm broad and 5–7 cm long; upper surface grey, brown-grey to dark brown, ± grey-tomentose (sometimes confined to lobe ends), with few to numerous scale-like schizidia, scattered or in dense overlapping clusters along the flat to upright margins of older parts and along fracture lines on the surface; lower surface with flattened veins, dark at the centre and pale towards the edge; rhizines dark towards the thallus centre, unbranched and ± smooth, not confluent. Apothecia rare, rounded, elongate or saddle-shaped. Ascospores 35–58 × 2.5–5 µm. Conidiomata unknown. Thallus with negative reactions; no lichen substances detected by TLC.
The separation of Peltigera membranacea and P. praetextata may present difficulties but the presence of schizidia and ± smooth rhizines in the latter species are diagnostic, although the schizidia are sometimes sparsely developed or even absent in abundantly fertile specimens.
On mossy trees, rotting logs, damp rocks and soil, often in sheltered situations.
Common, throughout Britain and Ireland, but very rare and declining in lowland central England and rare in the central plain in Ireland and in historically deforested parts of north east 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.
Text by Neil A Sanderson based on Cannon et al (2021)