Flora of New Zealand Series

Type : Placynthiella arenicola Elenkin [=Placynthiella hyporhoda (Th.Fr.) Coppins & P.James]

Description : Thallus crustose, effuse, dull-greenish to dark-brown often tinged reddish or reddish brown, of minutely granular or granular-isidiate goniocysts, or rounded granular areolae, corticate with an outer layer of brown-walled, pseudoparenchymatous hyphae. Photobiont green, ? Chlorella, cells 7–10 μm diam. Ascomata apothecia, adnate to sessile, reddish brown to black, thalline exciple absent, proper exciple present but often becoming excluded, disc concave to convex. Exciple brown, pseudoparenchymatous. Hymenium I+ greenish blue. Hamathecium of paraphyses, slender, 1–1.5 μm diam., often branched, apices swollen with a dark-brown cap, 2.5–5(–7) μm diam. Asci clavate, 8-spored, Trapelia -type (Purvis et al. 1992: 661, fig. 33m; Malcolm & Galloway 1997: 187), apical dome not, or weakly, amyloid. Ascospores simple, ellipsoidal, thin-walled, smooth, non-halonate, sometimes with a single large oil drop or several smaller oil droplets. Conidiomata unknown.

Placynthiella is a genus of seven species (Ryan et al. 2004a), included in the family Agyriaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). It is discussed in Coppins & James (1984: 243–246), Coppins et al. (1987) and in Nimis & Poelt (1987: 218–220 – as Saccomorpha), and a helpful discussion on the validity of the genus name (versus Saccomorpha Elenkin) is recorded in Nimis et al. (1997). Two species are known from New Zealand, where they are found on peaty soils, rotting wood, stumps and old fence posts.