Celothelium ischnobelum (Nyl.) M.B. Aguirre

Bull. Brit. Mus. Nat. Hist., Bot. ser., 21: 139, 1991. Basionym: Melanotheca ischnobela Nyl. - Flora, 59: 238, 1876.
Synonyms: Leptorhaphis carrollii A.L. Sm.; Leptorhaphis ischnobela (Nyl.) Coppins; Tomasellia ischnobela (Nyl.) Keissl.; Verrucaria myriospora Leight.
Distribution: C - Tosc. S - Camp (Puntillo & al. 2000).
Description: Thallus crustose, endosubstratic, smooth and continuous, greenish-white, pale yellow to cream-coloured, somehow shiny, sometimes delimited by a dark brown prothalline line, composed of colourless to pale brown, thin-walled, smooth, cylindrical, <4 μm thick hyphae constricted at septa, mixed with bark cells, associated with trentepohlioid algae below the surface. Perithecia black, shiny, brittle, smooth, scattered or clustered in small groups, circular to ellipsoid, 0.45-1 mm across, at first immersed, then projecting, hemispherical to flattened, dimidiate, the ostiole located in a small central papilla. Involucrellum blackish, brittle, covering groups of perithecia, c. 50 μm thick, composed of bark material mixed with reddish-brown, thick-walled, smooth, 2-3 μm thick hyphae, forming a clypeus of textura epidermoidea; exciple intergrading with the involucrellum, mainly differentiated at the margins of perithecia, sometimes extending below, colourless to brownish, c. 30-40(-50) μm thick, consisting of colourless to brown hyphae intermixed with bark cells forming a textura intricate; paraphysoids < 2 μm thick; hymenial gel I+ blue. Asci 8-spored, cylindrical, bitunicate, the outer layer thin and smooth, the inner without an apparent internal apical beak, I- but with a meniscus staining I+ dark blue near the apex. Ascospores 8-many-septate, hyaline, thread-like, sometimes helically twisted, 80-110 x 1.5-2.5 μm, thin-walled. Pycnidia black, shiny, circular to elongated, smooth, at first immersed, then projecting, hemispherical-dimidiate, with a dark brown to blackish wall. Macroconidia multiseptate, thread-like, hyaline, 60-100 x 1.5-2 μm. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a mild-temperate to subtropical, doubtfully lichenised species found on smooth bark, especially of Corylus and Ilex in sheltered and humid situations, with an apparently western distribution in Europe; to be looked for further in Tyrrhenian Italy. The species is included in the Italian red list of epiphytic lichens as “Endangered” (Nascimbene & al. 2013c).
Growth form: Crustose
Substrata: bark
Photobiont: 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: extremely rare
Humid mediterranean belt: extremely rare
Dry mediterranean belt: absent


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Poleotolerance:

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Altitudinal distribution:

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Natural History Museum, University of Oslo, Norway- CC BY-SA NC