Synonyms: Collema lichinodeum Nyl. ex Cromb.; Omphalaria radiata (Sommerf.) Forssell; Synalissa lichinodea (Nyl. ex Cromb.) Arnold; Thyrea radiata (Sommerf.) Zahlbr.
Description: Thallus foliose, loosely attached, dark green and gelatinous when wet, black and hard when dry, with radiating, usually divergent, linear and strap-shaped, sometimes weakly channelled, 5-8 mm long, 0.3-0.8(-1) mm wide, sparingly dichotomously branched lobes, forming up to 3 cm wide rosettes. Central parts of thallus with clusters of globose to clavate isidia, sometimes also with globose hormocystangia producing hormocysts measuring c. 30 x 10 μm. Apothecia extremely rare (not known in European material), immersed in the thallus. Asci 8-spored, cylindrical, prototunicate, without a distinct apical apparatum. Ascospores 1-celled, hyaline, broadly ellipsoid, 14-23 x 8-12 μm. Pycnidia rather frequent, immersed. Conidia simple, hyaline, bacilliform, 3.5-5.5 x c. 1 μm. Photobiont cyanobacterial (Nostoc, in disintegrating chains) ), the individual cells 4.5-5.5 μm wide. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on long-time moist, mostly calcareous rocks, often amongst bryophytes, near and above treeline; known from cool to cold parts of the Holarctic region, with a few records from the Eastern Alps (Austria). To be looked for in the Italian Alps.