


Australian Biological Resources Study
| Checklist of the Lichens of Australia and its Island Territories | ||
| Introduction | A–D | E–O | P–R | S–Z | Oceanic Islands | References | ||
| Myriotrema viridialbum (Kremp.) Hale | ||
| Mycotaxon 11: 135 (1980) Thelotrema viridialbum Kremp., Flora 49: 221 (1876); — Ocellularia viridialba (Kremp.) Müll.Arg., Flora 70: 398 (1887); — Rhabdodiscus viridialbus (Kremp.) Vain., Ann. Acad. Sci. Fenn., ser. A, 15(6): 184 (1921). T: Rio de Janeiro, Brazil, A.Glaziou 3193; lecto: M, fide M.E.Hale (in herb.); isolecto: C. | ||
| Thallus usually epiphloeodal, to c. 700 µm thick,  pale yellowish to greenish grey or olive, dull to glossy, smooth, continuous to  rugose, rarely verrucose, usually rimose. True cortex ±continuous, yellowish, to  c. 50 µm thick, consisting of periclinal hyphae. Algal layer well developed,  continuous; calcium oxalate crystals absent or sparse, then large and clustered;  medulla distinct. Vegetative propagules not seen. Ascomata to c. (0.5–) 0.8 mm diam.,  mostly ±rounded, apothecioid, occasionally solitary but often fused, immersed  to ±emergent in older ascomata, then hemispherical to urceolate. Disc occasionally  becoming partly visible from above, pale flesh-coloured, pruinose. Pores small  to gaping, to c. (0.3–) 0.6 mm diam., ±rounded, entire to slightly split;  proper exciple often becoming apically or completely visible from above,  off-white, sometimes slightly shrunken, incurved. Thalline rim margin becoming  moderately wide to gaping, ±rounded, thick, predominantly ±entire, whitish or  brighter than the thallus; thalline rim incurved. Proper exciple fused to  partly or entirely free, thick to thin, with or without a thin hyaline area  internally, completely or marginally greyish, sometimes faintly amyloid.  Hymenium to c. 160 µm thick, not inspersed, occasionally with large ±columnar  aggregates of bacilliform crystals (soluble in K), strongly conglutinated;  paraphyses thick, irregular, often distinctly septate, ±interwoven, with  thickened irregular tips; lateral paraphyses and true columella absent;  columella-like structures sometimes present in fused ascomata. Epihymenium  hyaline, with greyish granules. Asci 8-spored; tholus thin to thick. Ascospores  submuriform, subglobose to ellipsoidal or somewhat clavate, with ±rounded to  subacute ends, rarely acute, hyaline, strongly amyloid, 10–20 × 5–12 µm, with 3–6  × 1–2 (–3) locules; locules ±rounded, subglobose to lentiform; end cells the  same shape, hemispherical or conical; septa thick, often irregular; ascospore  wall thick, often thinly halonate; endospore thick. Pycnidia immersed or in distinct thallus warts, with a brownish  pore area surrounded by a bright ±eroded ring. Conidia fusiform, to c. 6 × 1 µm. CHEMISTRY: Thallus K–, C–, P–, UV±; containing hypoprotocetraric acid (major), 4-O-demethylnotatic acid (minor to trace), convirensic acid (minor to trace), conhypoproto-cetraric acid (minor to trace), conprotocetraric acid (trace), ±lichexanthone. | ||
| Rare on bark in rainforest in north-eastern Qld, at altitudes of 600–1100 m. Previously known from the Neotropics. | ||
| Mangold et al. (2009) | ||
| Checklist Index | 
| Introduction | A–D | E–O | P–R | S–Z | Oceanic Islands | References | 
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