Synonyms: Lithophyllum tortuosum (Esper) Foslie (1900a) p. 20; Tenarea tortuosa (Esper) Lemoine (1910) p. 368; not Lithophyllum lichenoides (Ellis) Rosanoff ex Hauck (1883) p. 268; Lithophyllum cristatum Meneghini (1840); Lithophyllum hieroglyphicum Zanardini (1843); Spongites cristata Kützing (1849) p. 698; Lithophyllum crassum, Rosanoff (1866) p. 95; Melobesia crassa Lloyd (1886); Lithophyllum lichenoides Philippi (1837) p. 389.

VEGETATIVE FEATURES

Thallus habit: hemispherical, cushion-like bearing many adventitious more or less erected lamellae with alveolated surface (A). Lamellae with entire margin; saw-like, hard, more or less anastomosed edge; basal crust strongly encrusting the substratum. Size: (4) 8-15 (45)cm diameter, height up to 2cm, lamellae thickness 0.8mm. Colour of living specimen: violet pink. Colour of dried specimen: violet grey (mauve).

Basal filaments: multilayered, straight, sometimes horizontal, rectangular cells (basal crust), long and narrow: 18-25 (30)µm long x 5 µm in diameter (lamellae) and 15-20µm long x 4-6-µm in diameter (basal crust). Erect filaments: multilayered, straight rectangular cells arranged in more or less loosely aggregated rows: 12-16µm long x 5-6µm in diameter (lamellae) and 10-15µm long x 4-5µm in diameter (basal crust) (B). Epithallial cells: arranged in 3-4 isodiametric rows: 4-6µm long x 3-6µm in diameter (B). Cell connections: secondary pit-connections.

Gametangial conceptacles: spermatangial with elliptical, elongated chambers: 83-130µm in diameter x 36-52µm high; carposporangial with flask-shaped chambers: 95µm in diameter x 95-100µm high. Tetra/bisporangial conceptacles: uniporate, slightly raised (C), hemispherical, elliptical chambers: 138-156µm in diameter x 65-91µm high, frequent presence of a central columella. Other features: old spermatangial conceptacles become buried in the thallus while spermatangial and carposporangial ones become sloughed off. Phenology: ---

Habitat: it grows on rocky substrata developing hemispherical cushion-like thalli, which may group to one another. In sheltered conditions the bio-constructions can be completely above the sea level up to 20-30cm. Bathymetric distribution: midlittoral. Geographic distribution: (Babbini & Bressan 1997):

Alboran Sea (A): Morocco; Western Mediterranean Sea (African shores) (B): Algeria, Tunisia; Middle Western Mediterranean Sea (C): Spain, France, Italy; North Western Mediterranean Sea (D): Spain, France, Italy; North Adriatic Sea (E): Italy, Croatia; Middle Adriatic Sea (F): Italy, Croatia; South Adriatic Sea (G): Italy, Albania; South Eastern Mediterranean Sea (H): Italy, Malta; Middle Eastern Mediterranean Sea (L): Italy, Greece; North Eastern Mediterranean Sea (M): Greece, Turkey.