Lecanographaceae Zwackhia sorediifera (Opegrapha sorediifera) Growth type crustose. Identification: Bryan Edwards, Vince Giavarini Chemical results: Soralia K-, C+ pink-red, KC+ red, P-, UV- On bark of deciduous trees in damp woodlands (especially Salix and Acers) Smooth or scurfy brownish thallus with pale orange-yellow or buff punctiform soralia. Usually found sterile but when present apothecia are semi-immersed to sessile, the disc slit-like. Spores are 30-40(-58) x 4-5 µm, 10-14 septate. Microscope photograph below. Similar: O. corticola, larger soralia. C-, UV+/-pale fawn. O. multipuncta, fleck-like soralia. C-. Zwackhia viridis (O.viridis) is the fertile counterpart, C-, spores (8-)11-15 septate with distinct gelatinous sheath

Microscope photograph

Opegrapha sorediifera
Holton Lee, Dorset. March and November 2013