Flora of New Zealand Series

Holotype: New Zealand: Otago, track from Mt Cargill to Bethune's Gully, tributary of Lindsay's Creek, c. 200 m, on moderately shaded, semi-aquatic, siliceous rock, 17.ix.1998, P.M. McCarthy 1323 – OTA.

Description : Thallus epilithic, diffuse to determinate, medium-green to grey-green, ±smooth, full, 20–50(–80) μm thick, continuous to sparingly cracked, somewhat gelatinous when moist, ecorticate, not impregnated with rock crystals and fragments, K−. Photobiont green, Trentepohlia, cells 8–20 × 5–15 μm. Prothallus not apparent. Basal layer absent. Perithecia ±superficial, moderately numerous. Perithecial apex usually rounded, occasionally plane. Ostiole inconspicuous. Involucrellum applanate to convex (0.28–)0.36(–0.48) mm diam., dull greyish black in surface view, purple-black in section and K+ reddish, 40–50 μm thick near ostiole tapering to c. 20 μm thick at base, overgrown and impregnated by thallus almost to apex, diverging from excipulum below ostiole. Old perithecia leaving a blackish involucrellar ring and a pale inner ring of subinvolucrellar hyphae. Centrum depressed-ovate, 0.18–0.26 mm diam. Exciple uniformly hyaline or slightly darker towards ostiole, 14–18 μm thick. Subhymenium 10–20 m thick. Paraphyses unbranched, c. 1 μm wide. Periphyses absent. Asci elongate-cylindrical or narrowly obclavate with a truncate apex and a distinct, apical, chitinoid ring, 95–118 × 15–17 μm. Ascospores colourless, 7-septate, mostly broadly fusiform to elongate-fusiform, usually straight, ends rounded to subacute, lacking a gelatinous sheath, contents granular, (22–)27(–33) × (6.5–)8.5(–10) μm. Pycnidia sparse, semi-immersed, applanate to convex, blackish above, hyaline below, 80–120 μm diam., with a simple conidiogenous layer. Conidia fusiform, (2–)3–5(–6) × 1–2 μm.

S: Otago (Bethune's Gully, Mt Cargill). On semi-immersed rock in streambed (Lindsay's Creek). Associating with Anisomeridium laevigatum, Porina fluminea, P. guentheri, P. leptalea and Trichothelium javanicum. Other aquatic lichens collected in the area include Anisomeridium carinthiacum, Strigula johnsonii, S.aff.decipiens, Verrucaria aquatilis, V. hydrela and V. rheitrophila (McCarthy 1999c).

Endemic

Illustration : McCarthy (1999c: 338, fig. 1D).

Porina otagensis is characterised by: the saxicolous, semi-aquatic habit; a thin thallus; small to moderately large perithecia with a thin, spreading, thallus-impregnated involucrellum; rather short and broad, 7-septate ascospores; and fusiform conidia.