ITALIC 8.0

Placidiopsis tenella (Nyl.) Zahlbr.

Cat. Lich. Univ., 1: 204, 1922. Basionym: Endocarpon tenellum Nyl. - Ann. Sci. Nat., Bot., sér. 3, 20: 316, 1853

Synonyms: Bohleria tenella (Nyl.) Trevis.

Distribution: S - Bas (Potenza & al. 2010), Cal.

Description: Thallus squamulose, whitish to greenish grey, sometimes pale brown, epruinose, the squamules 1-2 mm broad, irregularly rounded to crenate-lobulate, flattened to convex, smooth, contiguous, not imbricate. Lower surface pale, attached by 2.5-4 μm thick, colourless rhizohyphae. Upper cortex pseudoparenchymatous, 10-25 μm thick, covered by a 10-15 μm thick epinecral layer; medulla often poorly developed, subparaplectenchymatous; lower cortex absent or very poorly developed. Perithecia frequent, laminal, immersed in the squamules, globose, with a colourless wall and a dark apical involucrellum, 0.2-0.3 mm across, the involucrellum small, flat, appearing as a blackish rim around the ostiole. Exciple colourless to pale brown, of tangentially arranged, elongate cells; periphyses present around the ostiole, measuring 20-30 x 2.5-3 μm, interascal filaments absent; hymenial gel hemiamyloid. Asci 8-spored, clavate, thin-walled, I-, apically slightly thickened, with a small ocular chamber, 60-70 x 13-16 μm. Ascospores 1-septate, hyaline, narrowly ellipsoid, thin-walled, 14-18 x 6-7 μm. Photobiont chlorococcoid (Diplosphaera). Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.

Note: this is a critical taxon. According to Breuss (1996) the species was often confused with P. cinerascens, from which it mainly differs in the presence of a small involucrellum, being known with certainty only from Algeria and Calabria. Molecular data by Prieto & al. (2010) revealed the presence of 2 clades in samples of P. cinerascens and P. tenella, but did not find any correlation between those and the presence/absence of an involucrellum, so that they proposed to consider P. tenella as a synonym of P. cinerascens. Pending further study, I still maintain here the two species as separate.

Growth form: Squamulose

Substrata: soil, terricolous mosses, and plant debris

Photobiont: green algae other than Trentepohlia

Reproductive strategy: mainly sexual

Poorly known taxon in need of further study

Commonnes-rarity: (info)

Alpine belt: absent

Subalpine belt: absent

Oromediterranean belt: absent

Montane belt: absent

Submediterranean belt: extremely rare

Padanian area: absent

Humid submediterranean belt: absent

Humid mediterranean belt: extremely rare

Dry mediterranean belt: extremely rare

pH of the substrata:

1

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5

(info)

Solar irradiation:

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5

(info)

Aridity:

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(info)

Eutrophication:

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(info)

Poleotolerance:

0

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3

(info)

Altitudinal distribution:

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6

(info)

Predictive model

Index Fungorum GBIF

P.L. Nimis; Owner: Department of Life Sciences, University of Trieste

Herbarium: TSB (15753)
2001/11/28