Lecanora horiza (Ach.) Linds.

Trans. Bot. Soc. Edinburgh, 9: 96, 1869. Basionym: Lecanora subfusca var. horiza Ach. - Lichenogr. Univ.: 394, 1810.
Synonyms: Lecanora laevis Poelt; Lecanora oleae Reichert & Galun; Lecanora palestinica Räsänen; Lecanora parisiensis Nyl.; Lecanora sienae B. de Lesd.?
Distribution: N - Emil (Nimis & al. 1996, Benesperi 2009, Fariselli & al. 2020), Lig (Valcuvia & al. 2000, Giordani & Incerti 2008). C - Tosc (Loppi & Putortì 1995, Loppi & al. 1995, 1997, 1997b, 1998, 1998b, 2002, 2002c, 2003, 2004, 2004c, 2006, Loppi 1996, 1996b, Loppi & De Dominicis 1996, Putortì & al. 1998, Putortì & Loppi 1999, Bacci & al. 2000, Benesperi 2000a, Senese & Critelli 2000, Loppi & Frati 2004, Frati & al. 2006b, Paoli & Loppi 2008, Brunialti & Frati 2010, Loppi & Nascimbene 2010, Brunialti & al. 2012b), Marc (Nimis & Tretiach 1999, Frati & Brunialti 2006), Umb (Ravera 2000, Panfili 2000b, Ravera & al. 2006, Panfili 2007), Laz (Bartoli & al. 1997, Loppi & Pirintsos 2000, Massari & Ravera 2002, Ruisi & al. 2005, Ravera 2008b, Ravera & Genovesi 2008), Abr (Recchia & al. 1993, Olivieri & al. 1997, 1997b, Loppi & al. 1999, Nimis & Tretiach 1999, Stofer 2006, Gheza & al. 2021), Mol (Nimis & Tretiach 1999, Caporale & al. 2008, Paoli & al. 2015), Sar (Zedda 2002, 2002b, Zedda & al. 2001, Rizzi & al. 2011). S - Camp (Ricciardi & al. 2000, Aprile & al. 2003b, Nimis & Tretiach 2004, Garofalo & al. 2010, Brunialti & al. 2013, Ravera & Brunialti 2013, Catalano & al. 2016), Pugl (Durini & Medagli 2002, 2004, Grube & al. 2004, Brackel 2011), Bas (Nimis & Tretiach 1999, Potenza 2006, Paoli & al. 2006, Potenza & al. 2010, Brackel 2011), Cal (Puntillo 1996, Incerti & Nimis 2006), Si (Merlo 1993, Nimis & al. 1994, 1996b, Ottonello & Salone 1994, Ottonello & al. 1994, 2011, Grillo & Cristaudo 1995, Ottonello 1996, Grillo & Carfì 1997, Grillo 1998, Grillo & al. 2002, 2007b, Grillo & Caniglia 2004, 2006, Caniglia & Grillo 2006b, Brackel 2008b, Liistro & Cataldo 2011).
Description: Thallus crustose, episubstratic, continuous to faintly rimose, white to pale yellowish white, sometimes delimited by a dark prothallus. Apothecia lecanorine, sessile to slightly constricted at base, 0.4-1(-1.2) mm across, with a dark reddish brown, often glossy, flat disc, and a smooth, persistent thalline margin. Thalline exciple corticate, the cortex 15-20 µm thick laterally, expanding to 40-85(-150) µm at base, with fine granules soluble in K (visible under polarized light), clearly separated from the medulla by a crystal-free zone; proper exciple colourless, with crystals soluble in K; epithecium red-brown to orange-brown, the pigment not dissolving in K, without crystals; hymenium colourless; paraphyses not or only slightly thickened at apex; hypothecium colourless, not inspersed with oil droplets. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 11-17 x (5.5-)6-9(-9.5) µm. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C-, KC-, P- or P+ pale yellow. Chemistry: atranorin, plus a complex of unknown terpenoids.
Note: a mainly Mediterranean species found on smooth bark of isolated broad-leaved trees, much rarer in the North than in Mediterranean Italy. According to Malícek (in litt.) the synonymisation of L. sienae with L. horiza might prove to be incorrect: although the former is a very variable species, L. sienae would represent a real extreme in its variation range.
Growth form: Crustose
Substrata: bark
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: absent
Submediterranean belt: very rare
Padanian area: absent
Humid submediterranean belt: common
Humid mediterranean belt: very common
Dry mediterranean belt: very 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 4.0
TSB 16584



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (38263)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (38263)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (38263)
2008.02.25



A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Isola di Marettimo
2008.04.05



A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Isola di Marettimo
2008.04.05



A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Isola di Marettimo
2008.04.05



G. Incerti CC BY-SA 04
TSB 30190