Collema nigrescens (Huds.) DC.

in Lamarck & de Candolle, Fl. Franç., éd. 3, 2: 384, 1805. Basionym: Lichen nigrescens Huds. - Fl. Angl.: 450, 1762.
Synonyms: Collema nigrescens f. quinqueseptatum (Kernst.) Zahlbr.; Collema nigrescens var. rosaceum Flot.; Collema vespertilio (Lightf.) Hoffm.; Lathagrium fasciculare (L.) A. Massal.; Lathagrium nigrescens (Huds.) Gray; Lichen verspertilio Lightf. nom. illegit.; Synechoblastus nigrescens (Huds.) Trevis.; Synechoblastus nigrescens f. quinqueseptatum Kernst.; Synechoblastus vespertilio (Lightf.) Hepp
Distribution: N - VG, Frl, Ven (Caniglia & al. 1999, Nascimbene & Caniglia 2003c), TAA (Nascimbene & al. 2007b), Lomb (Valcuvia & Truzzi 2007b), Piem (Isocrono & al. 2004, Giordani & Malaspina 2016), VA (Piervittori & Isocrono 1999), Emil (Gasparo & Tretiach 1996, Benesperi 2009, Brackel 2015, Fariselli & al. 2020), Lig (Brunialti & al. 1999, Giordani & al. 2002, Brunialti & Giordani 2003, Giordani & Incerti 2008). C - Tosc (Tretiach & Nimis 1994, Loppi & al. 1998, 2002c, Putortì & al. 1998, Loppi & Frati 2006, Benesperi & al. 2007, Pasquinelli & al. 2009, Loppi & Nascimbene 2010, Benesperi 2011, Brackel 2015), Marc (Nimis & Tretiach 1999, Frati & Brunialti 2006), Umb (Ravera 1998, Ravera & al. 2006), Laz (Massari & Ravera 2002, Munzi & al. 2007, Brackel 2015), Abr (Recchia & al. 1993, Olivieri & al. 1997, 1997b, Loppi & al. 1999, Nimis & Tretiach 1999, Caporale & al. 2016, Gheza & al. 2021), Mol (Nimis & Tretiach 1999, Caporale & al. 2008, Brackel 2020), Sar (Zedda 1995, 2002, 2002b, Zedda & al. 2001, Rizzi & al. 2011, Cossu 2013). S - Camp (Aprile & al. 2003b, 2011, Nimis & Tretiach 2004, Catalano & al. 2016), Pugl (Nimis & Tretiach 1999), Bas (Nimis & Tretiach 1999, Potenza 2006, Brackel 2011), Cal (Puntillo 1995, 1996, Incerti & Nimis 2006), Si (Nimis & al. 1994, Ottonello & al. 1994, 2011, Ottonello 1996, Ottonello & Romano 1997, Schicchi & al. 1997, Grillo 1998, Grillo & Caniglia 2004, 2006, Brackel 2008b, 2008c, Ottonello & Puntillo 2009, Liistro & Cataldo 2011).
Description: Thallus foliose, homoiomerous, subgelatinous when wet, 1-5(-10) cm diam., adnate, broadly lobed. Lobes 0.5-1 cm wide, (60-)90-150 µm thick when wet, rounded and often somewhat ascending at apex, densely pustulate and coarsely ridged, dark olive-green to brown or rarely black, often pale yellowish brown in old parts. Isidia present or absent, granulose to slightly oblong, up to 0.2 mm wide. Lower surface greenish brown, pitted with a few hapters. Upper and lower cortices absent. Apothecia common in non-isidiate morphs, crowded (0.4-)0.6-1(-1.5) mm across, with a plane to convex, brownish red disc and an entire, often isidiate thalline margin. Proper exciple thin, euthyplectenchymatous; hymenium colourless, 85-110 µm tall. Asci 8-spored, clavate, the apex thick, with a I+ blue apical dome and a I+ blue annulus projecting downwardly. Ascospores (4-)5-12-septate, hyaline, acicular to bacilliform, straight or spirally curved, 50-90(-110) x 3-4.5 µm. Pycnidia immersed or semi-immersed, on both sides of the thallus, pale. Conidia bacilliform or with slightly swollen ends, 4.5-6 x 1-1.8 µm. Photobiont cyanobacterial (Nostoc), in long chains. Spot tests: all negative. Chemistry: without lichen substances.
Note: a mainly temperate species found on more or less isolated trees (depending on air humidity), more common in the past, presently absent from heavily disturbed areas of the North, but locally still frequent in humid, semi-natural habitats, with optimum in Tyrrhenian Italy; the species is more wide-ranging in altitude and latitude than the closely related C. subnigrescens. The recent record from Tuscany by Pasquinelli & Puccini (2010), judging from the pictures and the description, is certainly wrong.
Growth form: Foliose, broad lobed
Substrata: bark
Photobiont: cyanobacteria, filamentous (e.g. Nostoc, Scytonema)
Reproductive strategy: mainly asexual, by isidia, or isidia-like structures (e.g. schizidia)
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: extremely rare
Submediterranean belt: very rare
Padanian area: absent
Humid submediterranean belt: rather common
Humid mediterranean belt: common
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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P.L. Nimis CC BY-SA 4.0
TSB 36982



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (27109)
2001/12/04
detail of isidia



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (9785)
2001/12/04



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (30652)
2002/12/03
fertile specimen


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25



Curtis Randall Björk – CC BY-SA 4.0
Near Metchosin, British Columbia, Canada


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/


Degelius G. 1954. The lichen genus Collema in Europe: Morphology, Taxonomy, Ecology. Symbolae Bot. Upsal. 13, 2: 1-499.


Degelius G. 1954. The lichen genus Collema in Europe: Morphology, Taxonomy, Ecology. Symbolae Bot. Upsal. 13, 2: 1-499.


Zahlbruckner A. 1926. Lichenes (Flechten). In: Engler A. (ed.): Die natürlichen Pflanzenfamilien. 2nd ed., vol 8, W. Engelmann, Leipzig, 270 pp.



P.L. Nimis CC BY-SA 4.0
TSB 9785



P.L. Nimis CC BY-SA 4.0
TSB 9785



P.L. Nimis CC BY-SA 4.0
TSB 9785



P.L. Nimis CC BY-SA 4.0
TSB 9785



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (9785)
2001/12/04
detail of apothecia