Porina chlorotica
≡Verrucaria chlorotica Ach., Lichenogr. universalis: 283 (1810).
Description : Thallus on rocks, continuous, cracked or areolate, pale to medium grey-brown or greenish brown, to 0.1 mm thick, ecorticate; prothallus blackish or not apparent. Photobiont Trentepohlia; cells 6–14 × 5–12 µm. Perithecia superficial, hemispherical to subglobose, 0.18–0.32 mm diam.; apex rounded or very slightly pointed; ostiole inconspicuous. Involucrellum dull- black, contiguous with and almost enclosing the exciple, not enclosing algae, greenish black to purple-black in thin section. Exciple 10–15 µm thick, hyaline to black. Centrum 0.13–0.22 mm wide. Asci ±cylindrical-clavate, 80–112 × 6–10 µm. Ascospores fusiform or oblong, 3-septate, 16–32 × 4–6 µm; perispore usually not apparent. Pycnidia hemispherical, c. 0.1 mm diam., black. Conidia fusiform, 2–3 (–4) × 0.7–1 µm.
N: Wellington (Titahi Bay) on coastal slate. S: Otago (Maungatua) on siliceous rocks. Elsewhere in its range it is a pioneer species colonising small, siliceous pebbles, generally in shaded, humid habitats. It is known from Great Britain, Europe, Scandinavia, Asia, North America, Hawai'i, South Africa, Juan Fernandez, Australia, Christmas I. And Macquarie I. (Purvis & James 1992e; McCarthy 1993b, 2001f, 2001l, 2003c; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Diederich & Sérusiaux 2000; Scholz 2000; Aptroot 2002d). A detailed list of taxonomic synonyms and of the geographical distribution of this species is given (together with a map) by McCarthy (2003d: 28–31, fig. 3).
Cosmopolitan
Illustrations : Keissler (1938: 301, figs 96–99); Swinscow (1962: 22, fig. 1); Dobson (2000: 316; 2005: 356).
Porina chlorotica is characterised by: the saxicolous habit; the thin, olivaceous brownish or green-black thallus; the rather small, prominent, shiny black perithecia; and 3-septate ascospores (McCarthy 2001f: 121).
