ITALIC 7.0

Placynthium rosulans (Th. Fr.) Zahlbr.

Cat. Lich. Univ., 3: 235, 1925. Basionym: Lecothecium corallinoides subsp. rosulans Th. Fr. - Bot. Not.: 12, 1863.

Synonyms: Placynthium pannariellum (Nyl.) H. Magn. var. rosulans (Th. Fr.) Degel.

Distribution: N - Piem (TSB 34355).

Description: Thallus crustose-placodioid, dark olive-green to olive-brown, developing on a dark blue-green hypothallus, forming 0.5-3 cm wide rosettes. Central parts of thallus irregularly areolate, the areoles 0.4-1.6 mm wide and up to 0.4 mm thick; marginal lobules flat to slightly convex, finely striate, 0.3-0.6(-1) mm long and 0.2-0.6(-1.2) mm wide, usually contiguous and radiating; prothallus absent or thin, dark blue. Upper cortex thin, olivaceous green; medulla white, rather thick; lower cortex paraplectenchymatous, with abundant dark rhizohyphae. Apothecia lecideine, sessile, 0.4-0.8(-1) mm across, with a concave to finally convex, dark brown to black disc, and a blackish to dark bluish brown, finally often excluded proper margin. Proper exciple dark bluish green; epithecium dark grey-brown; hymenium colourless, 120-130 µm high; paraphyses distinctly septate, sparingly branched; hypothecium colourless. Asci 8-spored, apically thickened, with an amyloid cap. Ascospores (1-)2-3-septate, hyaline, cylindrical to narrowly ellipsoid, (10-)12-18(-20) x (4-)5-6 µm. Pycnidia immersed, with a dark blue ostiolar region. Conidia 5-7 x c. 1 µm. Photobiont cyanobacterial, Scytonema-like. Spot tests: all negative. Chemistry: without lichen substances.

Note: a northern species found on moist siliceous rocks, e.g. in inundation zones along brooks, near or above treeline; known from a few localities in the Alps, but perhaps more widespread. The relationship with P. pannariellum still needs further study; in my opinion, the two taxa may prove to be not distinct.

Growth form: Crustose

Substrata: rocks

Photobiont: cyanobacteria, filamentous (e.g. Nostoc, Scytonema)

Reproductive strategy: mainly sexual

Periodically submerged (e.g. in creeks)

Poorly known taxon in need of further study

Commonnes-rarity: (info)

Alpine belt: very rare

Subalpine belt: extremely rare

Oromediterranean belt: absent

Montane belt: absent

Submediterranean belt: absent

Padanian area: absent

Humid submediterranean belt: absent

Humid mediterranean belt: absent

Dry mediterranean belt: absent

pH of the substrata:

1

2

3

4

5

(info)

Solar irradiation:

1

2

3

4

5

(info)

Aridity:

1

2

3

4

5

(info)

Eutrophication:

1

2

3

4

5

(info)

Poleotolerance:

0

1

2

3

(info)

Altitudinal distribution:

1

2

3

4

5

6

(info)

Predictive model

Herbarium samples

Index Fungorum GBIF

Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php

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

Herbarium: TSB (34348)
2002/01/07
center of thallus

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

Herbarium: TSB (34348)
2002/01/07
marginal lobes