Porina mastoidea
≡Pyrenula mastoidea Ach., Ges. Naturforsch. Fr. Berl. Mag. 6: 16 (1814).
Description : Thallus epiphloeodal or epilithic, continuous to areolate, pale-grey, pale khaki-grey or pale grey-green, matt to glossy, smooth to irregularly rugulose, (50–)100(–200) µm thick, K+ dull orange-brown or red-brown, corticate, usually with a brown-black basal layer; prothallus whitish, brown-black or not apparent. Photobiont Trentepohlia; cells 8–16 × 8–13 µm. Perithecia convex to hemispherical, 0.36–0.9 mm diam.; wall containing a layer of colourless crystals; apex plane to convex; ostiole inconspicuous or in a shallow depression or a papilla; periostiolar area usually black, 0.05–0.2(–0.3) mm diam. Involucrellum apical to dimidiate, pale- to medium-brown below the apex, 20–40 µm thick. Exciple 20–25 µm thick, pale yellow-brown to orange-brown. Centrum 0.25–0.44 mm wide. Asci elongate-cylindrical, 115–162 × 16–25 µm. Ascospores fusiform to elongate-cylindrical, 7(–8)-septate, 32–66 × 6–13 µm; perispore 1.5–3.5 µm thick. Pycnidia semi-immersed to almost completely immersed, 80–140 µm diam., resembling miniature perithecial verrucae. Conidia fusiform to elongate-fusiform, 3–5 × 1 µm.
N: Wellington. On rocks and tree bark. Still very poorly known and collected here. A widely distributed tropical taxon. A detailed geographical distribution of the species (plus map) is given in McCarthy (2003d: 66–68; 67, fig. 6).
Pantropical
Illustration : McCarthy (1993b: 74, fig. 19).
Porina mastoidea is characterised by: the corticolous and saxicolous habit; pale-grey to pale grey-green, smooth to wrinkled thallus (K+ orange-brown or red-brown); perithecia in swollen thalline verrucae; fusiform to elongate-cylindrical, 7(–8)-septate ascospores, 32–66 × 6–13 µm, with a well-developed perispore.
