Strigula fossulicola
Description : Thallus crustose, foliicolous, subcuticular, determinate, continuous, non-lobate or with shallow, rounded lobes, usually mottled-white, pale-grey or pale-green, smooth to minutely uneven, dull to slightly glossy to 5 mm diam., 20–50(–70) μm thick, ecorticate, without a prothallus. Photobiont Cephaleuros, cells irregularly oblong, 8–16 × 5–8 μm. Perithecia very numerous, almost completely immersed, solitary or 2–3 together. Involucrellum apical to dimidiate, convex, jet-black and glossy when exposed, often appearing dark-grey when partly overgrown by thallus, 0.25–0.4(–0.5) mm diam., 25–50 μm thick; surface commonly uneven, transition from thallus usually not abrupt. Ostiole inconspicuous. Exciple c. 10 μm thick, medium- to dark-brown towards apex, colourless at base and lower sides. Centrum depressed-globose, 0.2–0.35 mm diam. Subhymenium c. 10 μm thick. Paraphyses simple to sparingly branched, 1–2 μm thick. Periphyses absent. Asci clavate, 28–35 × 5.5–7 μm; lateral walls c. 1 μm thick; apex rounded, ocular chamber minute, tubercular, seen only when immature, lateral walls and apex I−, ascoplasm I+ red-brown. Ascospores 8 per ascus, colourless, elongate-ellipsoidal to elongate-fusiform, 1-septate, 8–10 × 2–2.5 μm, spore halves separating at septum early in development, 16 per ascus, irregularly massed, contents with 1–2 oil bodies, 4–5(–6) × 2–2.5 μm. Pycnidia of two types: (1) 60–100 μm diam., immersed, glossy black above, pale- to dark-brown below, with a simple conidiogenous layer and elongate-fusiform microconidia, 2–3 × 0.5 μm; (2) 80–120 μm diam., immersed, glossy black above, colourless to brown below, macroconidia ellipsoidal, (2–)2.5–4 × 1.5–2 μm, simple, with 2 oil bodies, often appearing 1-septate through a median concentration of cytoplasmic material, bounded by a very thin gelatinous sheath, apices occasionally with gelatinous appendages to 1 μm long.
N: Northland (Ngaiotonga Saddle, Pukekawa, Ravensthorpe). On leaves of Alectryon excelsum and Beilschmiedia tawa, the known New Zealand collections all made by the late John Bartlett (Sérusiaux 1998a: 150). Also known from Lord Howe I. (McCarthy 1996, 2003c, 2006).
Australasian
Illustrations : McCarthy et al. (1996b: 241, fig. 1); Sérusiaux (1998: 148, fig. 3).
Strigula fossulicola is characterised by: semicircular thalli with small, rounded lobes, growing near margins of leaves or around leaf wounds or tears; immersed perithecia; small, clavate asci (28–35 × 5.5–7 μm); and small ascospores (8–10 × 2–2.5 μm), breaking into two parts at the septum while still within the ascus.
