Placynthium dolichoterum (Nyl.) Trevis.

Placynthium dolichoterum (Nyl.) Trevis.

Sched. ad Lich. Ven. Exs.: nr. 98, 1869. Basionym: Pannaria dolichotera Nyl. - Lichenes Scand.: 127, 1861.

Synonyms: Parmeliella melantera (Stirt.) A.L. Sm.; Placynthium pluriseptatum (Arnold) Arnold

Distribution: N - Frl, Ven (Nascimbene & al. 2021), TAA (Nascimbene & al. 2022), Lig.

Description: Thallus crustose, rimose-areolate, dark dark olive-green to almost black, somewhat shiny, 0.15-0.5(-1) mm thick, the areoles isodiametrical, mostly angular, 0.15-0.8 mm wide, covered in verrucose-papillate, isidioid outgrowths throughout, forming up to 3(-4) cm wide patches, usually without a distinct prothallusor with a poorly evident blue hypothallus visible between the areoles. Upper cortex indistinct, the thallus otherwise paraplectenchymatous throughout, without a distinct medulla; lower cortex dark, paraplectenchymatous, giving rise to dark rhizohyphae. Apothecia biatorine, black, up to 1(-1.5) mm across, with an initially concave, then flat to convex, smooth, shiny disc and a thin, finally often excluded, shiny proper margin. Proper exciple dark purplish brown, 65-70 µm wide; epithecium dark blue-green; hymenium colourless, 75-80(-110) high; paraphyses distinctly septate, sparingly branched; hypothecium pale brown. Asci 8-spored, apically thickened, with an amyloid cap. Ascospores 3-5-septate, hyaline, narrowly cylindrical to fusiform, (25-)27-40(-50) x (3-)4-6(-7) μm. Pycnidia 90-150 μm across, the wall blue at least in upper part. Conidia bacilliform, (4-)5-6 x c. 1 μm. Photobiont cyanobacterial, Scytonema-like. Spot tests: all negative. Chemistry: without lichen substances.

Note: on basic siliceous or slightly calciferous rocks in humid-sheltered situations near or above treeline, on occasionally inundated boulders along mountain streams, also on mosses and inclined rock faces long moistened from seeping water. According to Roux & coll. (2014) it is fairly common in the Western Alps.

Growth form: Crustose

Substrata: rocks

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

Reproductive strategy: mainly asexual, by isidia, or isidia-like structures (e.g. schizidia)

Poorly known taxon in need of further study

Commonnes-rarity: (info)

Alpine belt: extremely rare

Subalpine belt: rare

Oromediterranean belt: absent

Montane belt: extremely rare

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

Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placynthium_dolichoterum.htm

France, 2014 - Vanoise, Mont Cenis - Haute-Savoie

Source: Czeika & Czeika, Herzogia 20: 44, 2007.

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Czeika & Czeika, Herzogia 20: 44, 2007.

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Juri Nascimbene CC BY-SA 4.0

Italy, Veneto, Alps

Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placynthium_dolichoterum.htm

France, 2014 - Vanoise, Mont Cenis - Haute-Savoie

Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placynthium_dolichoterum.htm

France, 2014 - Vanoise, Mont Cenis - Haute-Savoie

Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placynthium_dolichoterum.htm

France, 2014 - Vanoise, Mont Cenis - Haute-Savoie

Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placynthium_dolichoterum.htm

France, 2014 - Vanoise, Mont Cenis - Haute-Savoie

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