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Physconia grisea (Lam.) Poelt

Data Set Maintenance: Data set compiled. Data set author(s): Helms G. (00-11-30).

Nomenclature: Current taxonomic status: accepted. Taxonomic rank: species. Physconia. Physciaceae Zahlbr. (1898); Lecanorineae; Lecanorales.

Taxonomic Literature: Purvis et al., Nat.His. Museum Pub.: 472, (1992).

Biogeography: Cosmopolitan; colline and submontane. Continent: Africa, Asia-Temperate, Australasia, Europe, and Northern America. Checklist records: Australia, Austria, Germany, Great Britain, Italy, New Zealand, Sweden and Norway, and United States and Canada (continental).

Ecology: Biotroph; lichenized; corticolous; episubstratic; growing sun-exposed; under conditions which are dry; substrate calciferous.

Thallus: Foliose, not subdivided or subdivided into main parts, irregular, continuous throughout, lobed; lobes horizontal; separate thallus parts.6-2 mm wide. Thallus Size and Differentiation: Up to 8 cm in diameter; apex rounded. Thallus Outline: Irregular; soon disappearing. Upper Surface: Grey or grey-brown, matt (in non-pruinose parts); pruinose; pruina abundant; whitish; continuous, at periphery; eciliate; without hairs; isidiate; isidia marginal (also laminal in the thallus-centre); sorediate; soralia lateral (also laminal in the thallus-centre). Lower Surface: Present, white or pale brown, brown in the centre, white along the margin, firmly attached attached; attached by holdfasts; rhizinate; rhizines central or peripheral, abundant, white, pale grey, or pale brown.

Photobiont Layer: Single-layered. Medulla: White.

Reproduction Strategy: Rarely with sexual (and possible asexual) stages. Ascocarps: Forming in the thallus centre, soon sessile or substipitate, sparse, up to 3 mm in diam.. Margin: Lecanorine, persistent, distinct; isidiate; not ciliate; not hirsute. Disk: Excavate or plane; grey-blue (due to pruina); pruinose, pruina abundant, pale grey (also bluish grey).

Ascospores: Physconia-type, 22-34 µm long, 12-17 µm wide.

Conidia: 4-7 µm long; 1-2 µm wide.

Spot Tests: Medulla: K –.

(report generated 13.Nov.2007)


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