Porina fluminea
Holotype: New Zealand. Wellington, Akatarawa Valley, Waterfall creek, 360 m, on stable siliceous rocks emergent from bed of shaded forest stream, 1.vi.1993, P.N. Johnson 670 – CHR 494624.
Description : Thallus crustose, epilithic, continuous, very dark greyish green, brighter green when wet, matt, smooth, 20–40 μm thick, ecorticate; marginal prothallus visible as fine, blackish lines separating contiguous thalli. Perithecia very numerous, hemispherical, slightly to almost completely overgrown by thalline tissue, (0.2–)0.3(–0.37) mm diam.; apex rounded; ostiole inconspicuous or minutely papillate. Involucrellum apical or dimidiate with a dark-greenish grey to green-black, outer layer 15–25 μm thick, paler within and containing photobiont cells. Centrum subglobose to depressed-ovate, 0.1–0.15 mm diam. Exciple hyaline, 12–20 μm thick. Periphyses absent. Paraphyses simple, c. 0.8 μm thick. Asci elongate-cylindrical to almost elongate-fusiform, apex rounded to subacute, 90–100 × 16–18 μm. Ascospores hyaline, 5-septate, elongate-ellipsoidal, subcylindrical or subfusiform, usually with rounded ends, irregularly biseriate in ascus, (18–)23(–30) × (5–)6.5(–8) μm. Pycnidia numerous, semi-immersed to almost entirely immersed, green-black above, hyaline below, 60–90(–100) μm diam. Conidia elongate-fusiform, 2.3–5 × 0.8 μm.
N: Wellington (Akatarawa Valley). S: Otago (Bethune's Gully Dunedin). On streamside rocks. Known also from alpine New South Wales (McCarthy 2003a, 2003c, 2003d, 2006).
Australasian
Illustration : McCarthy & Johnson (1995: 500, fig. 1).
Porina fluminea is characterised by: the aquatic, saxicolous habit; the thin, dark, continuous thallus; small perithecia variously overgrown by thalline tissue; and persistently 5-septate ascospores. McCarthy & Johnson (1995: 501) discuss differences between P. fluminea and the eastern Australian P. heterocarpa P.M. McCarthy, and the Malesian P. muluensis P.M.McCarthy & Coppins.
