Xanthocarpia lactea auct. non (A. Massal.) A. Massal.

Framm. Lichenogr.: 25, 1855. Basionym: Callopisma ochraceum var. lacteum A. Massal. - Flora, 35: 572, 1852.
Synonyms: Blastenia lactea (A. Massal.) Trevis.; Callopisma luteoalbum var. lacteum A. Massal.; Caloplaca lactea (A. Massal.) Zahlbr.; Gyalolechia calcicola Galløe nom. inval.; Gyalolechia lactea (A. Massal.) Arnold; Placodium pyraceum var. lacteum (A. Massal.) A.L. Sm.
Distribution: N - VG, Frl (TSB 5345), Ven (Navarro-Rosinés & Hladun 1996, Arup & al. 2013), TAA (Nascimbene & al. 2022), Lomb, Piem (Morando & al. 2016), VA (Favero-Longo & Piervittori 2009), Emil (Nimis & al. 1996, Fariselli & al. 2020), Lig (Giordani & al. 2016). C - Tosc (Navarro-Rosinés & Hladun 1996, Loppi & al. 1998, 2004b), Marc (Nimis & Tretiach 1999), Umb (Genovesi & Ravera 2001, Ravera & al. 2006, Panfili 2007), Laz (Bartoli 1997b), Abr (Nimis & Tretiach 1999, Gheza & al. 2021), Mol (Nimis & Tretiach 1999, Caporale & al. 2008, Genovesi & Ravera 2014), Sar (Rizzi & al. 2011). S - Camp (Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl (Nimis & Tretiach 1999, Durini & Medagli 2002, 2004, Gianfreda & Matino 2020), Bas (Nimis & Tretiach 1999), Cal (CLU 12735), Si (Nimis & al. 1994, Ottonello & Salone 1994, Ottonello & al. 1994, 2011, Monte & Ferrari 1996, Poli & al. 1997, 1998, Grillo 1998, Caniglia & Grillo 2001, 2005, 2006, Grillo & al. 2001, 2002, 2007b, 2009, Grillo & Caniglia 2004, Brackel 2008c, Liistro & Cataldo 2011).
Description: Thallus crustose, endosubstratic, poorly visible or reduced to a few whitish granules, without a distinct prothallus. Apothecia 0.1-0.3 mm across, sessile, scattered, with a flat to slightly concave, yellow-orange disc covered in an abundant yellow pruina, and a concolorous, thin, smooth, persistent proper margin. Thalline margin poorly developed, sometimes visible only on the lower part of apothecia, finely granulose. Proper exciple prosoplectenchymatous, colourless within; epithecium brownish yellow, c. 10 µm thick, K+ red; hymenium colourless, 70-80 µm high; paraphyses simple or sparingly branched in upper part, 1.2-2 µm thick at base, the apical cells swollen, up to 5 µm wide; hypothecium colourless. 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, 11-14(-16) x 6-8.5(-9.5) µm, the equatorial thickening (“septum”) (1-)2-3(-3.5) µm (c. 1/8 of spore length). Photobiont chlorococcoid. Spot tests: apothecia K+ red. Chemistry: apothecia with parietin (major), fallacinal, emodin, teloschistin and parietinic acid (minor), corresponding with chemosyndrome A of Søchting (1997).
Note: a mainly Mediterranean early coloniser of small calcareous pebbles in open habitats (e.g. stony ground in dry grasslands). X. lactea s.str. is a strictly Mediterranean lichen, and some records from the Alps could refer to other Xanthocarpia-species. The name, as applied to the lichen described here, is illegitimate, as it is based on Callopisma ochraceum var. lacteum A. Massal., the type of which is a pale form of X. ochracea, while Caloplaca lactea (A. Massal.) Zahlbr. was based on Callopisma luteoalbum var. lacteum A. Massal., (see Navarro-Rosinés & Hladun 1996), which means that the epithet lactea based on the latter basionym cannot be recombined into Xanthocarpia.
Growth form: Crustose endolithic
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Pioneer species

Commonnes-rarity: (info)

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

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 04
TSB 5345



P.L. Nimis CC BY-SA 04
TSB 41376



P.L. Nimis CC BY-SA 04
TSB 41376


Courtesy Danièle et Olivier Gonnet - https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_X/Xanthocarpia_lactea.htm
France, session AFL 2015 - Saint-Sozy - Le Pied Saint Jean - Lot


Courtesy Danièle et Olivier Gonnet - https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_X/Xanthocarpia_lactea.htm
France, session AFL 2015 - Saint-Sozy - Le Pied Saint Jean - Lot


Courtesy Danièle et Olivier Gonnet - https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_X/Xanthocarpia_lactea.htm
France, session AFL 2015 - Saint-Sozy - Le Pied Saint Jean - Lot


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote


Manuel Gil
Spain, Canary Islands, Lanzarote