ITALIC 8.0

Acarospora variegata H. Magn.

K. svenska Vetensk-Akad. Handl., Ser. III 7, 4: 278, 1929.

Synonyms:

Distribution: N- Frl (Knudsen & al. 2024).

Description: Thallus crustose, endo- to episubstratic, white or brownish, rimose or areolate, 2-10 cm wide, 0.5-1 mm thick the areoles 0.6-0.7 mm wide. Hyphae either scattered, 3-4 μm thick, and encrusted with crystals, or as thin as 0.5 μm, sometimes appearing as chains of c. 2 μm wide, round to oval cells, becoming gelatinized and forming a white, obscure matrix inspersed with large to very fine substrate particles and scattered algal cells. Cortex 25-40 μm thick; algal layer not coherent, the algal cells clustering around the sides of emerging apothecia and scattered beneath them; a distinct medulla is lacking. Apothecia usually elevated, 0.2- 0.3 mm across, the disc brown, usually slightly lower than the brown, epruinose margin. Proper exciple 30-60 μm wide; epithecium brownish: hymenium colourless, (100-)120-150(-170) μm high, the hymenial gel IKI+ blue, euamyloid in thick sections, in squash preparations K/I+ pale blue, but in some forms IKI+ blue turning red in part, but becoming dirty bluish brown and blue mixed; paraphyses 1-2 μm thick, the apical cells sometimes with visible gel caps; subhymenium c. 50 μm thick, IKI+ blue in part, the hypothecium merging with subhymenium and indistinct, but sometimes visible at base of the proper exciple. Asci multispored, clavate, the apical dome K/I-, 80-120 x 10-18 μm. Ascospores 1-celled, hyaline, narrowly ellipsoid, 2-5 x c. 1 μm. Photobiont chlorococcoid. Spot tests: thallus K-, C+ red, KC+ red, P-. Chemistry: gyrophoric acid unevenly present in the epithecium and/or in the margin of apothecia and the cortex.

Note: a recently-resurrected, apparently very rare and declining species known from a few sites in Central Europe (see Knudsen & al. 2024) growing on base-rich siliceous rocks.

Growth form: Crustose

Substrata: rocks

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: extremely rare

Padanian area: absent

Humid submediterranean belt: absent

Humid mediterranean belt: absent

Dry mediterranean belt: absent

pH of the substrata:

1

2

3

4

5

(info)

Solar irradiation:

1

2

3

4

5

(info)

Aridity:

1

2

3

4

5

(info)

Eutrophication:

1

2

3

4

5

(info)

Poleotolerance:

0

1

2

3

(info)

Altitudinal distribution:

1

2

3

4

5

6

(info)

Predictive model

Courtesy K. Knudsen. Source: Knudsen, K., Kocourková, J., Peksa, O., Beck, A., Velmala, S. & Wirth, V. 2024 Three poorly known Acarosporaceae of Central Europe: new reports from Czech Republic, Germany, and Italy. – Herzogia 37: 5 –15.

Acarospora variegata, Nylander 24831 (H). A – Habit of the epilithic areolate thallus. B – Detail of the thallus areoles with elevated apothecia. Scale: A, B=1 mm.

Courtesy K. Knudsen. Source: Knudsen, K., Kocourková, J., Peksa, O., Beck, A., Velmala, S. & Wirth, V. 2024 Three poorly known Acarosporaceae of Central Europe: new reports from Czech Republic, Germany, and Italy. – Herzogia 37: 5 –15.

Acarospora variegata, Nylander 24831 (H). A – Habit of the epilithic areolate thallus. B – Detail of the thallus areoles with elevated apothecia. Scale: A, B=1 mm.