Buellia sequax (Nyl.) Zahlbr.

Cat. Lich. Univ., 7: 410, 1931. Basionym: Lecidea sequax Nyl. - Flora, 58: 302, 1875.
Synonyms: Buellia excelsa (Leight.) A.L. Sm.; Lecidea excelsa Leight.
Distribution: C - Tosc (Bungartz & al. 2004). Sar (Giralt & al. 2011). S - Camp (TSB 32280), Si (Bungartz & al. 2004)
Description: Thallus crustose, episubstratic, from thin and poorly developed to areolate or even bullate-subsquamulose, whitish to grey, sometimes delimited by a grey prothallus. Medulla white, with crystals insoluble in K, not amyloid, I-. Apothecia lecideine, black, initially adnate but soon becoming sessile, crowded, often coalescing, to 0.5-0.6(-0.7) mm across, with a flat to strongly convex, epruinose disc, and an initially thick, then thinner and finally excluded proper margin. Proper exciple well developed, brown throughout, N-, up to 80 μm thick, dispersa-type, the inner part with crystals insoluble in K; epithecium brown, N-; hymenium colourless, 70-90 μm high, inspersed with numerous oil droplets; paraphyses coherent, the apical cells 3-4(-5) μm wide, with a brown cap; hypothecium brown, up to 150 μm high. Asci 8-spored, clavate, Bacidia-type. Ascospores 1-septate, not constricted at septum. brown, ellipsoid with usually pointed ends, (11-)13-15(-18) x (5-)6-7(-8) μm; young ascospores slightly thickened at apex and strongly thickened at septum (Dirinaria-type) or usually only thickened at septum (Physconia-type), the thickenings almost disappearing in mature ascospores (Buellia-type), smooth, with ontogeny of type B. Pycnidia dark, immersed. Conidia bacilliform, 4-5 x 1-1.2 μm. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C-, KC-, P-. Chemistry: atranorin, chloroatranorin and diploicin, usually with additional isofulgidin.
Note: a mild-temperate, mainly Mediterranean-Atlantic, much misunderstood species (see Giralt & al. 2011) found on siliceous rocks in the Mediterranean area.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)
Poorly known taxon in need of further study

Commonnes-rarity: (info)

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


pH of the substrata:

(info)

1

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5

Solar irradiation:

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5

Aridity:

(info)

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4

5

Eutrophication:

(info)

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5

Poleotolerance:

(info)

0

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3

Altitudinal distribution:

(info)

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5





Felix Schumm; Owner: CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm; Owner: CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm; Owner: CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (21734)
2001/11/22



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger



Felix Schumm - CC BY-SA 4.0
[TSB 21734], Sardinia, Prov. Cagliari, WWF Oasis of Monte Arcosu, loc. Concale Petuntu, c. 600 m, on siliceous rocks . Leg. P.L. Nimis, 09.08.1989, rev.Rev. Ch. Scheidegger