Acarospora squamulosa (Schrad.) Trevis.

Riv. Per. Lav. Regia Accad. Sci. Lett. Arti Padova, 1: 263. 1853. Basionym: Lichen squamulosus Schrad. - Ann. Bot. (Usteri), 22: 84. 1797
Synonyms: Acarospora chalcophila H. Magn.; Acarospora fuscata var. peliscypha (Th. Fr.) Nyl.; Acarospora montana H. Magn.; Acarospora nitrophila var. chalcophila (H. Magn.) Clauzade & Cl. Roux; Acarospora peliscypha Th. Fr.; Acarospora rugulosa Körb.?
Distribution: N - TAA, Lomb, Piem (Matteucci & al. 2015b), VA (Piervittori & Isocrono 1999, Matteucci & Vanacore Falco 2015). C - Sar.
Description: Thallus crustose, episubstratic, areolate-subsquamulose, pale brown to dark chestnut brown, mostly shining, usually forming large patches. Areoles very variable in size and shape, 0.5-3.5 mm wide, usually convex, sometimes subglobose, black in lower part along the margins, dispersed or contiguous. Upper cortex 30-50 µm thick, the cortical cells 3-5 µm wide, overlain with an amorphous layer; algal layer continuous; medulla white; lower cortex 10-15 µm thick, black. Apothecia lecanorine, at first impressed, but soon prominent, 0.3-1.4 mm across, with a very rough, strongly rugose, often umbonate, dark reddish brown disc surrounded by a thick, shiny, prominent thalline margin. Excipullum 6-15(-30) µm thick at the base, 30-60 µm thick in upper part, I-; epithecium brown; hymenium colourless, 90-100 µm high, I+ greenish blue or brownish yellow; paraphyses 1.5-2 µm thick, more or less swollen at apex, the apical cells 2.5-5 µm wide; hypothecium opaque, 25-50 µm high. Asci 100-200-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, subcylindrical, 3-6 x 1.2-2 µm. Pycnidia immersed, with a colourless wall. Conidia 1.7-2 x c. 1 µm. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C+ red, KC+ red, P-. Chemistry: gyrophoric acid.
Note: an arctic-alpine to boreal-montane, probably circumpolar species found on siliceous, often iron-rich substrata, on exposed birds' perching rocks (e.g. windy ridges, isolated boulders), with optimum near or above treeline. See also note on A. bullata. For nomenclatural matters see Knudsen & al. (2019).
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Species of metal-rich rocks

Commonnes-rarity: (info)

Alpine belt: very rare
Subalpine belt: rare
Oromediterranean belt: extremely rare
Montane belt: extremely rare
Submediterranean belt: absent
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
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; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (33838)
2001/12/09



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (33838)
2001/12/09


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


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


Magnusson A. H. (1935) Acarosporaceae, Thelocarpaceae. - In: Rabenhorst G. L.: Kryptogamen-Flora von Deutschland, Österreich, und der Schweiz-. 2nd- IX. Die Flechten. Abt. 5- 1. Gebr. Borntraeger. Leipzig, pp. 1-318. – Public Domain