Rhizocarpon tavaresii Räsänen

Arch. Soc. Zool.-Bot. Fenn. Vanamo, 3: 85, 1949.
Synonyms: Diplotomma geographicum f. tenellum (Müll. Arg.) Jatta?; Rhizocarpon geographicum f. tenellum Müll. Arg.?
Distribution: C - Tosc, Sar. S - Bas (Puntillo & al. 2012), Cal (Puntillo 1996), Si.
Description: Thallus crustose, episubstratic, areolate, bright yellow-green, dull, delimited by a thin dark prothallus, forming patches 1-5 cm in diam. Areoles contiguous, angular, 0.1-0.6 mm wide, often subdivided into smaller units by cracks, mostly flat. Cortex c. 35 μm thick; medulla white, I+ blue. Apothecia lecideine, black, developing inbetween the areoles, 0.2-0.7 mm across, round to angular, with a flat to slightly concave disc and a thin proper margin. Proper exciple brown and K+ brownish red in outer part, paler within; epithecium greenish, poorly delimited against the hymenium, K+ intensifying green or red; hymenium greenish, (65-)120-160 μm high; paraphysoids strongly conglutinate, richly branched and anastomosing, apically clavate; hypothecium brown, 50-100 μm high, K-. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus, lacking an ocular chamber, Rhizocarpon-type. Ascospores strongly muriform, dark brown, oblong-ellipsoid, 25-40 x 13-16 μm. Photobiont chlorococcoid. Spot tests: medulla K-, C-, KC-, P+ red-brown or P+ yellow. Chemistry: cortex with rhizocarpic acid; medulla with stictic or psoromic acids.
Note: a mainly south European, poorly known taxon found on basic siliceous rocks at relatively low elevations.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Poorly known taxon in need of further study

Commonnes-rarity: (info)

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

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


Pier Luigi Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (18195)