Pyrenodesmia helygeoides (Vain.) Arnold

Verh. zool.-bot. Ges. Wien, 47: 215, 1897.. Basionym: Lecanora helygeoides Vain. - Medd. Soc. Fauna Flora Fenn., 6: 148, 1881.
Synonyms: Callopisma diphyodes (Nyl.) Bagl. & Carestia sensu Baglietto & Carestia; Caloplaca diphyodes auct. ital. non (Nyl.) Jatta; Caloplaca diphyodes var. helygeoides (Vain.) H. Olivier; Caloplaca diphyodes var. helygeoides (Vain.) H. Olivier; Caloplaca helygeoides (Vain.) Dalla Torre & Sarnth.
Distribution: N - Frl (TSB 10027), TAA (Nascimbene 2003, Nascimbene & al. 2004, 2004b), Piem (Isocrono & al. 2004), Lig.
Description: Thallus crustose, episubstratic, rimose-areolate, dirty white-grey, pale brown or brown-black, to 0.3 mm thick, without a distinct prothallus. Apothecia zeorine/lecideine, round or irregular in outline, 0.2-1.2 mm across, slightly immersed to sessile, with a black, epruinose or initially faintly pruinose, flat to slightly convex disc, a thin, often soon excluded, whitish thalline margin, and a very thin, poorly evident proper margin which, when wet, appears as a darker ring around the disc. Thalline exciple corticate at least in upper part, brownish to grey in outer part, colourless within; epithecium pale brown, brown or almost colourless, K- or usually K+ weakly purple, C+ purple, N+ purple, without an epipsamma; hymenium colourless 73-110 μm high, usually inspersed with oil droplets; paraphyses sparingly branched, 1-5.2.5(-3) μm thick, the apical cells to 5.5 μm wide; hypothecium colourless, 70-125 μm high. Asci 8-spored, clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, 12.5-18 x 6.5-11.5 μm, the equatorial thickening (“septum”) 3-7 μm. Pycnidia black, immersed. Conidia 1-celled, hyaline, 3-4 x 1.5-2 μm. Photobiont chlorococcoid. Spot tests: cortex K+ weakly violet, C-, KC-, P-. Chemistry: cortex and sometimes epithecium with the Sedifolia-grey pigment.
Note: on siliceous rocks, incl. calciferous schists and serpentine, in alpine-subalpine sites. The species has been much misunderstood: it has been frequently synonymised with "Caloplaca" diphyodes, which is a more or less aquatic, lowland species described from central France, which is different from the Alpine populations and belongs to Kuettlingeria.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Poorly known taxon in need of further study

Commonnes-rarity: (info)

Alpine belt: very 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:

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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


P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (13369)
2001/11/13


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_5/Pyrenodesmia_heligeoides.htm
France, 14/9/2014 - Darois - Côte-d'Or - (21) - Au dessus de Val Suzon, Combe En Neudry, alt.: 470 m