Flora of New Zealand Series

Type : Biatora lucida (Ach.) Fr. [=Psilolechia lucida (Ach.) M.Choisy]

Description : Thallus crustose effuse, ecorticate, leprose, leprose-granular, or rarely granular-areolate, consisting predominantly of ±globular or short, filament-like goniocysts. Goniocysts comprising a cluster or chain of photobiont cells surrounded by short-celled hyphae (c. 1–3 μm wide, mostly constricted at septa); interconnected by occasional, slender, long-celled hyphae 1–2 μm wide. Photobiont green, Trebouxia or Stichococcus. Trebouxia cells ±globose, 5–10 μm diam., to ellipsoidal, 9–12 × 7–8 μm. Stichococcus cells ±cuboid to oblong, 3.5–12 × 2.5–4 μm, usually arranged in characteristic pairs or short chains; occasionally some cells misshapen, irregularly globose or ellipsoidal, up to 8 μm wide. Ascomata apothecia, convex, immarginate from the beginning, soon ±globose, small, 0.1–0.5 mm diam., sometimes becoming tuberculate and up to 1(–1.5) mm diam., variously coloured. Hymenium shallow, 25–35 μm tall, hyaline, I+ blue; epithecium pigmented. Paraphyses ±conglutinate in K, scanty to numerous, simple or 1–2-branched, occasionally anastomosing, septate, 1–2 μm wide, apices often thickened to 3 μm wide, but never pigmented or surrounded by a gel-like cap. Hypothecium convex-hemispherical to ±globose, 50–70 μm thick, hyaline or pigmented, I−. Exciple indistinct, sometimes visible as a narrow zone of radiating hyphae adjoining the reflexed edge of hymenium, with protruding hyphae 1.5–2 μm wide and to 60 μm long. Asci 8-spored, cylindrical-clavate, apical tholus I+ pale-blue with a central, elongate dark-blue tube-like structure (Hafellner 1984: 306; Malcolm & Galloway 1997: 187), the wall is non-amyloid but is surrounded by a thin, dark-blue outer layer. Ascospores oblong-ovoid to tear-shaped, simple, rarely 1-septate, hyaline, without a perispore, small, 4–7 × 1–2 μm.

Psilolechia is a genus of four species (Kirk et al. 2001), formerly included in the family Micareaceae (Hafellner 1984, 1987; Eriksson et al. 2004; Pennycook & Galloway 2004), but now transferred to Pilocarpaceae (Andersen & Ekman 2005; Eriksson 2005). All species of Psilolechia are found in shaded, humid situations such as on vertical rocks and walls, in underhangs, and on clay banks or among exposed tree roots, rocks, stones, soil and plant debris. P. lucida is commonly seen on building materials in towns in the Northern Hemisphere. With the exception of P. lucida, the genus is still rather poorly known and collected, although it is widely distributed in temperate regions of the world (Europe, Macaronesia, North America, Costa Rica, Hawai'i, and Australasia). Two species are known from New Zealand (Coppins & Purvis 1987), but the genus is still very poorly collected and understood here.