Flora of New Zealand Series

Type : Phyllopsora breviuscula (Nyl.) Müll.Arg. [=Lecidea breviuscula Nyl.]

Description : Thallus squamulose, rarely appearing subfoliose or crustose, commonly with a pale-whitish to dark-red marginal, byssoid prothallus, or prothallus only visible between thalline squamules. Squamules 0.1–1 mm diam. Isidia common, sometimes forming a dominant crust over the entire thallus. Upper cortex 5–60 μm thick, of anticlinally arranged, thin- to thick-walled hyphae with round to narrowly cylindrical lumina. Photobiont in a continuous layer, green, unicellular, 5–15 μm diam., ? Pseudochlorella. Medulla usually poorly developed, of loosely interwoven, non-amyloid hyphae, commonly containing lichen compounds. Lower cortex absent. prothallus pale- to dark-red, visible at margins or between squamules. Ascomata apothecia, to 1.5 mm diam., simple or aggregated. Disc plane to convex, pale yellow-brown to dark red-brown, epruinose, margins often slightly raised. Exciple of radiating hyphae, yellow-brown to dark-red, sometimes with crystals or pigments reacting K− or K+ red or purple-brown. Hypothecium similar to exciple. Hymenium I+ blue, 20–60 μm tall, epithecium indistinct. Hamathecium of paraphyses, straight, sparingly branched and anastomosing, apical cell slightly swollen, Asci elongate–clavate, with a well-developed tholus with a paler, conical masse axiale. Ascospores 8 per ascus, simple to 1-septate, colourless, ovoid, ellipsoidal to fusiform, smooth-walled, non-halonate, (4.5–)5–20 × 2.5 μm. Conidiomata pycnidia, spherical, immersed to superficial, outer wall yellow-brown to red-brown, ostiole pale to brown. Conidiophores irregular to branched. Conidiogenous cells elongate, enteroblastic. Conidia bacillar, straight or curved, 9–15 × 0.5–1 μm.

Phyllopsora, included in the family Ramalinaceae (Brako 1991; Ekman 1996a; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005) is distinguished from other genera in that family by the combination of a squamulose to subfoliose thallus with an obvious prothallus; an ascus type having an amyloid apical dome and a narrow, conical masse axiale; a distinctive apothecium composed of highly gelatinised hyphae with no clear distinction between exciple and hypothecium and with the same texture found at the centre and margins of the apothecium as well as in the paraphyses; by small, thin-walled, rarely septate ascospores; and by a chemistry comprising argopsin, atranorin, chlorophyllopsorin, furfuracein, methyl 2,7-dichloropsoromate, methyl 2,7-dichloronorpsoromate, norargopsin, norvicanicin, pannarin, vicanicin, zeorin. and several unidentified compounds. Timdal & Krog (2001: 60) record that valuable taxonomic characters for the genus are: growth form; presence and nature of vegetative propagules; pruinosity and pubescence of thallus; type and thickness of upper cortex; degree of pigmentation in exciple and hypothecium; ascospore size and shape; and to a certain extent, colour and thickness of the prothallus.

Presently, 25 species and 11 varieties are recognised in the genus, with a mainly pantropical to subtropical (rarely temperate) distribution (Swinscow & Krog 1981, 1986a, 1988; Galloway 1983a, 1985a; Brako 1989, 1991; Vězda 1995c; Timdal & Krog 2001; Upreti et al. 2003). Five taxa are here recorded from New Zealand, though the genus is still very much in need of further collection and study in the light of recent work on tropical taxa. Species are corticolous and characteristic of rotting logs or bark in lowland and coastal forest in deep to moderate shade.