Flora of New Zealand Series

≡Discosiella novae-zelandiae Nag Raj, Can. J. Bot. 59: 2528 (1981).

Holotype: New Zealand. South Auckland, Papakura, Kirk's Bush on leaves of Beilschmiedia taraire, 20.xii.1973, B. Kendrick KNZ 32B – PDD 40205.

Description : Thallus foliicolous, subcuticular, on surface of leaves, almost never at leaf margins or along leaf scars, forming circular colonies, 3–6 (–10) mm diam., abundant, pale-green to ash-green (white when moribund), glossy surface, smooth to subirregular, margin always rounded, 0.1–0.3 mm wide, sometimes deeply digitate, the marginal lobes giving thalli a typically crenulate appearance, 40–50 μm thick, without a prothallus. Photobiont Cephaleuros, cells rectangular to rounded, 8–20 × 4–7 μm, yellowish green, arranged in rows. Perithecia rather sparsely developed, but numerous when present, slightly flattened; apex hemispherical to subconical, solitary or 2–3-together, typically arranged in a circle, immersed at first, later with more than half of outer surface exposed, black or greenish when still covered with thallus, smooth, glossy, 0.25–0.35(–0.4) mm diam., 0.2 mm tall; ostiole central. Involucrellum black, expanding laterally under thallus, 0.5– 0.6 mm diam., 25–35 μm thick near ostiole. Exciple pale-brown, less than 10 μm thick. Centrum rather flattened, 300–340 × 100 μm. Paraphyses simple or sparingly branched, c. 1 μm thick. Asci obclavate, apex thickened with a small ocular chamber, 55–60 × 10–12 μm. Ascospores 8 per ascus, biseriate in ascus, fusiform, ends acute becoming rounded, 1-septate, distal cell enlarged and somewhat swollen at maturity, not breaking into halves at septum, and without any terminal gelatinous appendages, 16–18(–22) × (3–)4.5–5 μm. Pycnidia producing abundant macroconidia, even on thalli with perithecia and sometimes overgrowing them, circular, 100–130 μm diam., solitary to aggregated in linear or irregular groups of 2–10, hemispherical, black, glossy with distinct, central ostiole; conidiogenous cells lining base of cavity cylindrical or slightly inflated at base; macroconidia abundant, sometimes protruding from pycnidium as a cylindrical, whitish cirrus, subapically produced, subcylindrical (ellipsoidal to bacillar) with rounded ends, proximal end with obconical, sublateral appendage, distal end with cap- or fan-shaped gelatinous appendage, 1-septate, septum thickened (1–1.5 μm thick) with a central pore (polarilocular), 13–17 × 3–4.5 μm. Microconidia not seen.

N: Northland (Church Road Scenic Reserve near Kaitaia, Orewa), Auckland (Titirangi), South Auckland (Ravensthorpe near Bombay Hills). On leaves of Beilschmiedia taraire and B. tawa.

Endemic

Illustrations : Nag Raj (1981: 2522, figs 11–13; 2524, fig. 25; 2530, figs 64–71); Sérusiaux (1998a: 148, figs, 5, 6; 149, fig. 7C, D).

Strigula novae-zelandiae is characterised by: the foliicolous habit; the circular thalli with a crenulate to a deeply digitate margin; and numerous pycnidia producing polarilocular macroconidia (it is the only species in Strigula having macroconidia with such thick septa separating the two cells – the septum is always perforated centrally). Originally described in the genus Discosiella Syd. & P.Syd. g Raj 1981), a genus that represents the anamorph of Strigula.