Verrucaria hydrela
Description : Thallus very thin, continuous, to sparingly rimose, dark-green, gelatinous when moist, 20–40(–60) μm thick. Perithecia subimmersed to superficial with a rounded to subconical apex. The involucrellum diverges from the exciple, 0.2–0.5 mm diam., and 30–45 μm thick, brown-black, penetrating to exciple-base level. Exciple colourless, 15–25 μm thick. Centrum globose, 0.13–0.25 mm diam. Asci 58–88 × 17–25 μm. Ascospores ellipsoidal, 15.5–28 × 6.5–12 μm.
N: Wellington (Somes I.). S: Otago (Nenthorn, Emerald Creek, Trotter's Gorge, Dunedin, Bethune's Gully). On shaded, wet rocks at edge of streams. Known also from Great Britain, Europe, Scandinavia, N America and SE Australia (Swinscow 1968; McCarthy 1991b, 1995e, 2003c; McCarthy & Johnson 1995; Santesson et al. 2004; Elvebakk & Bjerke 2006).
Cosmopolitan
Illustrations : Zschacke (1934: 235, fig. 104); Swinscow (1968: 49, fig. 7).
Verrucaria hydrela is an aquatic to semi-aquatic species characterised by: a thin, continuous to rimose, medium to dark-green thallus; moderately large perithecia with a characteristic spreading involucrellum; a colourless exciple; and moderately large ascospores, 15.5–28 × 6.5–12 μm.
