ITALIC 8.0

Rhizocarpon atroalbescens (Nyl.) Zahlbr.

Cat. Lich. Univ., 4: 322, 1927.. Basionym: Lecidea atroalbescens Nyl. - Flora, 67: 216, 1884.

Synonyms: Rhizocarpon eupetraeoides auct. non (Nyl.) Blomb. & Forssell

Distribution: N - Piem (TSB 33166).

Description: Thallus crustose, episubstratic, areolate, yellow-green to yellow-grey, forming up to over 5 cm wide patches, delimited by a conspicuous black prothallus, the areoles (0.3-)0.7-1.5 mm wide, smooth or rough due to shallow cracks, flat to slightly convex, aggregated and angular or scattered and more rounded. Medulla white, I+ blue-violet (rarely I-). Apothecia lecideine, black, round to angular, innate between areoles, 0.3-1.5 mm across, with a flat to slightly convex disc and a thin, finally excluded proper margin. Proper exciple olive-brown in outer part, pale brown to colourless within; epithecium olive-green to green- brown, K- or K+ purple-red; hymenium pale green to colourless, often with dark vertical streaks originating from the hypothecium; paraphysoids strongly coherent, richly branched and anastomosing, the apical cells sometimes slightly capitate; hypothecium dark brown. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus that is K/I- in lower part and K/I+ blue near the apex, lacking an ocular chamber, Rhizocarpon-type. Ascospores 1-septate, dark green to dark brown, broadly ellipsoid, 22-34 x 9-17 μm. Photobiont chlorococcoid. Spot tests: medulla, exciple and hypothecium K- or K+ red, C-, KC-, P- or P+ yellow-orange. Chemistry: rhizocarpic acid, plus norstictic or psoromic or bourgeanic acids.

Note: on weakly calciferous rocks near and above treeline; probably more widespread in the Alps. For nomenclatural matters see Fryday & al. (2024).

Growth form: Crustose

Substrata: rocks

Photobiont: green algae other than Trentepohlia

Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

Alpine belt: rare

Subalpine belt: very 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

P.L. Nimis CC BY-SA 04

TSB 33166

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

Herbarium: TSB (33166)
2001/12/01
detail of areole