Collemataceae Pseudoleptogium diffractum (Leptogium diffractum) Growth type foliose Chemical results negative. BLS conservation evaluation: NT NS Sc Rare, scattered and very local distribution on hard, damp limestone Blackish-brown thallus with narrow, radiating, finely divided convex lobes, the rosette centres with convex areoles or partially missing. Apothecia are very rare, spores multi-septate to weakly muriform, 15-30 x 8-12 µm. Similar: Other rosette-forming limestone lichens include Collema fragile, Leptogium massiliense and Placynthium subradiatum

Pseudoleptogium diffractum (Leptogium diffractum)
On limestone. Portland, Dorset. February 2016