Physconia fallax Essl.

Data Set Maintenance: Data set standard item. Data set author(s): Esslinger T. (99-11-16). Data set not to be published after submission.

Nomenclature: Current taxonomic status: accepted or basionymous. Taxonomic rank: species. Physconia. Physciaceae Zahlbr. (1898).

Biogeography: Continent: Northern America.

Ecology: Lignicolous or corticolous.

Thallus: Foliose, lobed; lobes with parallel margins, linear; rounded at the front; concave (irregularly) or usually plane; separate thallus parts.5-1.5 mm wide. Thallus Size and Differentiation: Up to 4.5 cm in diameter; apex not curved. Thallus Outline: Margin crenate. Upper Surface: Grey, brown, or grey-brown; pruinose; pruina abundant; often continuous or patchy; without hairs; not isidate; sorediate; soralia brown, grey-brown, or brownish yellow, peripheral (marginal on lobes), helmet-shaped or ear-shaped (by separation of the cortices (reminiscent of Xanthoria fallax)), linear (on lobe margins or axils), soredia coarse. Lower Surface: Black in the centre, brown or pale brown along the margin; rhizinate; rhizines moderately abundant, black, branched, squarrosely branched.

Upper Cortex: Outer cortical layer paraplectenchymatous. Medulla: White. Lower Cortex: Present; prosoplectenchymatous, of periclinal hyphae.

Reproduction Strategy: Only known as sterile, asexually reproducing form or with sexual (and possible asexual) stages. Ascocarps: Sparse, up to 2 mm in diam.. Margin: Lobulate (lobules often developing reflexed soralia on the ends).

Ascospores: 33-38 µm long, 15.5-18 µm wide.

Secondary Metabolites: Present; in soredia (or soralia), secalonic acid a.

Spot Tests: Present reactions. Cortex: KC –, – medulla: K – KC – soredia: K + deep yellow; KC + deep yellow or + orange (reactions may be obscured in the darker soredia).

(report generated 13.Nov.2007)