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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 polytretum Hale

Bull. Brit. Mus. (Nat. Hist.), Bot. 8: 291 (1981)

T: Kegalla, Sabaragamuwa, Sri Lanka, M.E.Hale 50238; holo: US; iso: BM.

  Thallus endophloeodal to epiphloeodal, to c. 300 µm thick, pale olive to yellowish grey or greyish, occasionally with paler patches due to an uneven algal layer, glossy, smooth, continuous to slightly rugose, non-rimose. True cortex continuous, slightly yellowish, to c. 30 µm thick, consisting of periclinal to irregular hyphae. Algal layer well developed, continuous, but occasionally partly thinning or absent; calcium oxalate crystals abundant, small to large, clustered, rarely scattered; medulla sometimes distinct. Vegetative propagules not seen. Ascomata usually inconspicuous, to c. 0.35 mm diam., ±rounded, apothecioid, solitary to marginally or rarely entirely fused, often densely clustered, immersed. Disc often becoming partly visible from above, pale flesh-coloured, epruinose to slightly pruinose. Pores to c. 0.2 mm diam., ±rounded to somewhat irregular, entire, rarely slightly split; proper exciple not visible from above. Thalline rim margin thin, brighter than the thallus, forming a narrow to moderately broad fawn to off-white ring, level with the thallus to somewhat raised; thalline rim incurved. Proper exciple fused, thin, hyaline to pale yellowish internally, pale orange to yellowish brown marginally, sometimes greyish brown apically, non-amyloid. Hymenium to c. 70 µm thick, not inspersed, strongly conglutinated; paraphyses straight to slightly bent, ±irregular and distinctly septate, parallel to slightly interwoven, with thickened somewhat irregular tips; lateral paraphyses and columellar structures absent. Epihymenium hyaline, occasionally with fine greyish granules. Asci 8-spored; tholus initially thick, not visible at maturity. Ascospores transversely septate, oblong to ellipsoidal or somewhat fusiform, with ±rounded to narrowly rounded ends, hyaline, usually strongly amyloid, 10–18 (–22) × 6–8 µm, with 3 or 4 locules; locules mostly ±rounded, subglobose to oblong or slightly irregular; end cells having the same shape or hemispherical to conical; septa thin to thick, ±regular; ascospore wall thick, occasionally thinly halonate; endospore thick. Pycnidia not seen.
CHEMISTRY: Thallus K–, C–, P+ yellowish to reddish; containing 2-hydroxy-hypoprotocetraric acid (major), convirensic acid (trace), 2-hydroxynornotatic acid (trace), hypoprotocetraric acid (trace).
  Rare on bark in rainforest in north-eastern Qld. Palaeotropical.  
  Mangold et al. (2009)  

Checklist Index
Introduction | A–D | E–O | P–R | S–Z | Oceanic Islands | References

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