Synonyms: (basyonim) Millepora tortuosa Esper (1796) p. 118; Goniolithon tortuosum (Esper) Foslie (1898) p. 9; Lithophyllum tortuosum (Esper) Foslie (1900) p. 20; Crodelia incrustans f. tortuosa (Esper) Heydrich (1911) p. 13.

VEGETATIVE FEATURES

Thallus habit : hemispherical cushion-like thalli with alveolated surface due to numerous adventitious erect and fragile lamellae. Thalli more or less anastomosing, growing from a basal crust not closely adherent, therefore easily detachable. The margin of lamellae is always roughly folded up and curled up, sometimes just thickened; whitish edge, lighter than the rest of thallus. Size: cushion-like thalli 24 (10)cm in diameter, up to 0.15mm thick. Colour of living specimen: pale pink, violet grey. Colour of dried specimen: yellow ivory-white.

Thallus organization: isobilateral structure (A). Basal crust: multistratose, unilayered thallus. Thickness of lamellae: 50-70µm; basal crust: 90-120µm. Basal filaments: unilayered, oblique, sinuate rectangular cells: 40-50µm long x 5-10µm in diameter (lamellae) and 80-100µm long x 4-15 (20)µm in diameter (basal crust). Erect filaments: present in conceptacles and contiguous lamellae. Epithallial cells: generally triangular, in longitudinal section 4-6µm. Cell connections: secondary pit-connections. Other features: trichocytes sometimes present (B).

Gametangial conceptacles: unknown. Tetra/bisporangial conceptacles: uniporate, conical or subhemispherical (C), elliptical, arising from both sides of lamellae; greater diameter 400-550µm, lower diameter 350-500µm, 150-175µm high. Phenology: ---

Habitat: species always submerged. Numerous alveoli of the surface seem to maintain the necessary damping for short periods of surfacing. It can occasionally be recorded under the canopy of Cystoseira amentacea (C. Agardh) Bory. Small Ceramium, Polysiphonia and Laurencia species are often found as epiphytes on thallus surface. Bathymetric distribution: littoral and upper sublittoral. Geographic distribution (Babbini & Bressan 1997):

North Western Mediterranean Sea (D): France; North Adriatic Sea (E): Croatia; Middle Adriatic Sea (F): Croatia; South Adriatic Sea (G): Italy, Albania; Middle Eastern Mediterranean Sea (L): Greece, Turkey, Syria; North Eastern Mediterranean Sea (M): Greece, Turkey.