Gyalolechia fruticum Arup, Nimis & Vondrák

Lichenologist, 57: 3, 2025.
Synonyms:
Distribution: C- Tosc (Arup & al. 2025), Laz (Arup & al. 2025), Sar (Arup & al. 2025). S - Pugl (Arup & al. 2025), Si (Arup & al. 2025).
Description: Thallus crustose, up to 3(-4) cm in diam., at first very thinly episubstratic and c. 0.1 mm thick, then 0.2(-0.4) mm thick, bright orange in sun-exposed specimens to yellow, rarely or almost white with a yellowish hue in shade-forms, continuous and smooth to rimose-areolate, often with a rough surface, usually surrounded by a pale prothallus. Algal layer c. 50 µm thick, discontinuous in young, thin thalli, continuous in well-developed thalli, overlain by an up to 80 µm thick epinecral layer, which is, in yellow-orange thalli, inspersed with anthraquinone crystals; true cortex and medulla absent. Apothecia biatorine, at first semi-immersed, then sessile, circular to finally irregular in outline, (0.2-)0.3-0.8(-1.1) mm across, with an initially deep orange, finally often dark rusty red to dark orange-red (rarely blackening with age), slightly concave to slightly convex, epruinose disc, the proper margin slightly paler orange but never yellow, smooth, at first c. 0.1 mm thick and slightly raised, finally level with disc or excluded. Proper exciple prosoplectenchymatous, with orange anthraquinones at surface, usually colourless inside, the hyphae arranged in a fan-shaped way, the outermost cells almost spherical, up to 4 µm wide; epithecium brownish orange, K+ purple-red, C–; hymenium colourless, (40-)50-70(-80) µm high, not inspersed with oil droplets; paraphyses simple or forked in upper part, not anastomosing, c. 1.5-2 µm thick at base, the apical cells (2-)2.5-3.5(-4) µm wide; hypothecium colourless, 90-110 µm high, formed of a thin prosoplectenchymatous tissue below a strongly developed subhymenium, usually densely inspersed with very small oil droplets not dissolving in K. Asci 8-spored, clavate, Teloschistes-type, 40-60 x 12-15 µm. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, (9-)10-14 x (4-)5-8(-9) µm, the equatorial thickening (“septum”) 4-6 µm. Pycnidia usually numerous, c. 0.1-0.2(-0.25) mm in diam., half- to fully immersed, visible as orange-red to dark red (rarely almost black) dots, with conidiophores of Umbilicaria-type (sensu Vobis 1980). Conidia short-bacilliform, 3-4 x 0.8-1(-1.3) µm. Photobiont chlorococcoid (Trebouxia decolorans). Spot tests: thallus and apothecia K+ purple-red, C-, KC-, P-, UV+ orange. Chemistry: thallus and apothecia with unchlorinated anthraquinones: parietin and emodin predominate in the apothecia, fragilin in the thallus.
Note: a recently-described, Mediterranean-Macaronesian species growing on coastal shrubs, more rarely on lignum, most often on undisturbed sand dunes. For further details see Arup & al. (2025).
Growth form: Crustose
Substrata: bark
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: absent
Submediterranean belt: absent
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: very rare
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


P.L. Nimis CC BY-SA 4.0
TSB 17325 – Italy, Sicily, Prov. Agrigento, Island of Linosa, Monte Nero, on Pistacia along the coast. 1992. Leg. P.L. Nimis - 35.858854 12.870150


Ulf Arup
Spain, Canary Islands, Tenerife, on Euphorbia balsamifera, Leg. Klepsland


J. Machac
Greece, Rhodos, epiphytic, Leg. H. Vondrak 27405


J. Machac
Greece, Rhodos, epiphytic, Leg. H. Vondrak 27463



P.L. Nimis CC BY-SA 4.0
TSB 17325 – Italy, Sicily, Prov. Agrigento, Island of Linosa, Monte Nero, on Pistacia along the coast. 1992. Leg. P.L. Nimis - 35.858854 12.870150



P.L. Nimis CC BY-SA 4.0
TSB 17325 – Italy, Sicily, Prov. Agrigento, Island of Linosa, Monte Nero, on Pistacia along the coast. 1992. Leg. P.L. Nimis - 35.858854 12.870150



P.L. Nimis CC BY-SA 4.0
TSB 6369 – Italy, Lazio, Prov. Rome, Presidential Estate of Castelporziano, on Juniperus macrocarpa on coastal dunes, 2-3 m, 1985. Leg. P.L. Nimis - 41.692302 12.379358



P.L. Nimis CC BY-SA 4.0
TSB 9972 - Italy, Lazio, Prov. Rome, Torvaianica (Pomezia), on bark of shrubs on coastal dunes, 4 m, 1987. Leg. P. L. Nimis & M. Tretiach - 41.612991 12.479019



P.L. Nimis CC BY-SA 4.0
TSB 6369 – Italy, Lazio, Prov. Rome, Presidential Estate of Castelporziano, on Juniperus macrocarpa on coastal dunes, 2-3 m, 1985. Leg. P.L. Nimis - 41.692302 12.379358



P.L. Nimis CC BY-SA 4.0
TSB 9972 - Italy, Lazio, Prov. Rome, Torvaianica (Pomezia), on bark of shrubs on coastal dunes, 4 m, 1987. Leg. P. L. Nimis & M. Tretiach - 41.612991 12.479019



P.L. Nimis CC BY-SA 4.0
TSB 9972 - Italy, Lazio, Prov. Rome, Torvaianica (Pomezia), on bark of shrubs on coastal dunes, 4 m, 1987. Leg. P. L. Nimis & M. Tretiach - 41.612991 12.479019



P.L. Nimis CC BY-SA 4.0
TSB 6369 – Italy, Lazio, Prov. Rome, Presidential Estate of Castelporziano, on Juniperus macrocarpa on coastal dunes, 2-3 m, 1985. Leg. P.L. Nimis - 41.692302 12.379358



Juri Nascimbene & Pier Luigi Nimis
Italy, Lazio, Roma, Tenuta Presidenziale di Castelporziano
27.06.2024
on Juniperus and Phillyrea, coastal sand dunes



Juri Nascimbene & Pier Luigi Nimis
Italy, Lazio, Roma, Tenuta Presidenziale di Castelporziano
27.06.2024
on Juniperus and Phillyrea, coastal sand dunes



Juri Nascimbene & Pier Luigi Nimis
Italy, Lazio, Roma, Tenuta Presidenziale di Castelporziano
27.06.2024
on Juniperus and Phillyrea, coastal sand dunes



Source: Arup U., Nimis P.L., Vondrák J., Svoboda S., Søchting U. 2025. A new epiphytic species of Gyalolechia with a maritime, Mediterranean-Macaronesian distribution. Lichenologist, 57, 2: 1-8.
Morphology and habitat of Gyalolechia fruticum. A & B, the type specimen. A, with predominant apothecia. B, with predominant pycnidia (red dots). C, whitish thallus without anthraquinones (Vondrák 27405). D, yellowish thallus with anthraquinones (Vondrák 27463). E, the dunes of Castelporziano (Italy), with old shrubs in the background. F, old Juniperus macrocarpa with suitable microhabitats for G. fruticum (Greece, Chrissi) (source: freepic.com). G, G. fruticum with Seirophora villosa on a twig of Pistacia (Italy, Castelporziano). Scales = 0.5 mm. In colour online.



Source: Arup U., Nimis P.L., Vondrák J., Svoboda S., Søchting U. 2025. A new epiphytic species of Gyalolechia with a maritime, Mediterranean-Macaronesian distribution. Lichenologist, 57, 2: 1-8.
Anatomy of Gyalolechia fruticum in vertical sections. A, thallus and apothecium, algal cells forming colonies in a discontinuous layer between phorophyte bark tissue (below) and an epinecral layer (above). B, detail of thallus; vivid fungal cells (stained) are mostly restricted to algal colonies, whereas the epinecral layer is without living mycobiont cells. C, biatorine apothecium, with inspersed hypothecium and occasional algal colonies in lower exciple. D, pycnidium with distinct anthraquinone pigmentation around the ostiolum. E, apothecium in polarized light with glowing anthraquinones, but without POL+ crystals in the hypothecium. F, polarilocular ascospore (13 μm in length). G, ascus with ascospores. H, Teloschistes-type ascus. I, conidiophores and conidia. A, B & I, in lactoglycerol cotton blue; C–G, in water; H, in Lugol’s solution after K treatment. Scales: A, C–E = 100 μm; B = 50 μm; G & H = 10 μm; I = 20 μm. In colour online.