Arthonia urceolata (Elenkin) Calat., Barreno & V.J. Rico

Bibl. Lichenol., 88: 70, 2004. Basionym: Conida urceolata Elenkin - Izv. Imp. St. Petersburgsk. Bot. Sada, 1, 4: 147, 152-154, 1901.
Synonyms:
Distribution: C - Tosc (Brackel 2016). S - Camp (Brackel 2016, 2021).
Description: Thallus inapparent, not lichenized, the hyphae developing within the thalli of epilithic Circinaria-species. Apothecia arthonioid, immarginate but often surrounded by a collar deriving from the thallus of the host lichen, brown-black to black, rounded, 0.1-0.5 mm across, mostly flat, usually clustered, immersed in small, discoloured, orbicular patches on the host thallus, finally only slightly raised. Proper exciple very poorly developed; epithecium brown, K-; hymenium colourless to straw-coloured, I+ reddish or purple, K/I+ blue; paraphysoids soon degenerating in a cinnamon brown mass; hypothecium poorly developed, colourless or yellowish, I+ and K/I+ blue. Asci 8-spored, broadly clavate to ovoid, semi-fissitunicate, with a large apical dome and a distinct ocular chamber. Ascospores 1-septate, not constricted at septa, with unequal cells, at first hyaline but finally turning pale yellowish brown, oblong-ellipsoid, 12-18 x 4.5-8 μm. Photobiont absent. Spot tests: K-, C- KC-, P-. Chemistry: without lichen substances.
Note: a non-lichenised parasite of Circinaria-species, especially of vagrant forms, widespread in Central Asia and in the central part of the Iberian Peninsula. Italian records need re-confirmation, being based on reports of A. glaucomaria by Jatta (1909-1911) “in thallo Aspiciliae calcareae L. in Etruria et in Campania”.
Growth form: Lichenicolous fungus
Substrata: rocks
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)
paras Circinaria spp.

Commonnes-rarity: (info)

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


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