Flora of New Zealand Series

≡Lichen gemmatus Ach., Lich. suec. prodr.: 17 (1799)["1798"].

Description : Flora (1985: 3–4).

N: S: Throughout. On the rough bark of introduced deciduous trees (Fraxinus, Quercus, Ulmus) in urban areas, though susceptible to atmospheric pollution. Widespread in Europe and Scandinavia (Poelt 1969; Nimis 1993; Santesson 1993; Diederich 1989; Boqueras 2000; Llimona & Hladun 2001) and also in Great Britain (Purvis et al. 1992) and North America (Esslinger & Egan 1995; Harris 1995; Nimis & Martellos 2003). First collected in New Zealand from the Bay of Islands by Joseph Hooker and recorded as Verrucaria alba in Babington (1855: 307); Verrucaria gemmata in Hooker (1867: 593) and as Acrocordia gemmata in Hellbom (1896: 137).

Cosmopolitan

Illustrations : Swinscow (1970: 224, fig. 2); Wirth (1987: 40); Dobson (1992: 41; 2000: 48; 2005: 54); Boqueras (2000: 62, fig. 5 D).

Acrocordia gemmata may be confused with Anisomeridium biforme, but this latter species has smaller perithecia (<0.5 mm diam.). It is characterised by: a thin, filmy whitish, smooth to cracked thallus; black, compound perithecia, 0.2–1 mm diam., erupting through surface of bark, or leaving small pits; one to several brownish apical ostioles; and ellipsoidal, 1-septate ascospores, 15–30 × 7–13 μm, the upper cell larger with a very complex dimple at apex, 2–5 μm diam.