Flora of New Zealand Series

≡Leiophloea praetermissa Trevis., Consp. Verruc.: 10 (1860).

Description : Thallus epilithic, superficial, rimose to areolate, pale greyish white to pale grey-green, (60–)80–140(–200) μm thick, not gelatinous when moist. Perithecia 0.2–0.3(–0.4) mm diam., immersed, the thallus only slightly raised in vicinity of ostiole. Involucrellum not spreading, thick, dark-brown to black. Exciple continuous, ±hyaline. Ascospores elongate-ellipsoidal to broadly fusiform, 17–27 × 6–11 μm.

S: Southland (South Fiord Lake Te Anau). On siliceous, lakeshore rocks. Known also from Great Britain, Europe, Scandinavia, North America, Asia, Hong Kong, New Guinea and E Australia including Lord Howe I. (Swinscow 1968; McCarthy 1995e; Orange 2000; McCarthy 2001j: 191, 2003c; Santesson et al. 2004; Elvebakk & Bjerke 2006).

Cosmopolitan

Illustrations : Zschacke (1934: 245, fig. 111); Swinscow (1968: 43, fig. 2); Orange (2000: 418, fig. 4).

Verrucaria praetermissa is an aquatic lichen characterised by: an unusually pale grey-green, areolate thallus; immersed, 0.2–0.3 mm diam., perithecia; a brown-black basal layer; and ascospores 15–24 × 6.5–9.5 μm. It is distinguished by the pale thallus dotted with the black tops of the perithecia, and by the elongate ascospores. It grows on ±continuously inundated hard, siliceous rocks, rarely on limestones in lakes and rivers.