Squamarina nivalis Frey & Poelt

in Poelt, Mitt. bot. Staatss. München, 2: 353, 1958.
Synonyms:
Distribution: N - TAA, Piem (Ravera & al. 2023b), VA (HAL-19091).
Description: Thallus squamulose to subcrustose, yellowish white, but usually cretaceous white-pruinose, closely adpressed, forming up to 5 cm wide, orbicular to irregular rosettes. Squamules 1-3 mm broad, contiguous, convex, the marginal ones more flattened, slightly longer or wider than the central ones, and indistinctly radiating; lower surface pale brown also in central parts. Upper cortex paraplectenchymatous, well delimited against the thick, white medulla. Apothecia frequent, rounded, lecanorine/zeorine, at first immersed, then adnate, 1-3 mm across, with a pale to reddish brown, flat to finally convex disc and a smooth, thin, often finally excluded thalline margin. Epithecium brownish, granular, 10-30 μm thick, with crystals sometimes penetrating into the hymenium; hymenium colourless, 70-85 μm high, hemiamyloid; paraphyses slightly thickened above; hypothecium colourless. Asci 8-spored, elongate-clavate, with a thin, outer amyloid layer and a thickened, amyloid tholus devoid of an ocular chamber, penetrated by an axial tube the sides of which stain I+ deeper blue, approaching the Porpidia-type. Ascospores 1-celled, hyaline, ellipsoid, thin-walled, (8-)11-15 x 5-8 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC- (or cortex KC+ yellowish), P-, UV-. Chemistry: cortex with usnic and isousnic acids.
Note: on wind-exposed outcrops of calcareous schists above treeline, sometimes on calciferous soil, reaching the nival belt in the Alps, where it is probably more widespread but certainly not common. The sample from Valle d’Aosta was collected by B. Feige near Plan Masson near Breuil, at 2500 m. The species is an altitudinal vicariant of the very similar S. lentigera, the distinction between the two species would need confirmation by a DNA-study.
Growth form: Crustose
Substrata: rocks, soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

Alpine belt: extremely rare
Subalpine belt: absent
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:

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Solar irradiation:

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Aridity:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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Predictive model
Herbarium samples
Index Fungorum GBIF


Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)



Pier Luigi Nimis - CC BY-SA 4.0
Alpi Cozie Ridge NW above Crissolo N above Pian di Melzè S-exposed slopes of calcareous schist (TSB 35340)