Rhodophyta, Order: Corallinales; Family: Corallinaceae. A recent investigation reveals that the Mediteranean Pseudolithophyllum expansum species is - in fact - Lithophyllum frondosum (Furnari et al., 1996.(

Etymology

Lithophyllum, means ‘stone-loving’ and frondosum, means ‘leafy’, which describes the structure of the thallus, which seems covered by foliage.

Description

The Lithophyllum frondosum is a calcified and flat alga, hard as rock to touch. However, it easily breaks upon careless

handling or when dislocated from a wall. The colony creates round thalli, arranged one atop the other, generally resembling an arrangement of roses.

Size

The colony can reach 20 cm. A single thallus is usually smaller than 5 cm in diameter and 1-2 mm thick.

Colour

The Lithophyllum frondosum is chalky pink, sometimes edging towards purple.

Special features

The alga is characterized by its colony shape, which resembles a rose, and by its habitat - hidden regions in the ocean depth.

Habitat

The Lithophyllum frondosum grows in places that are never exposed: in the inner, lowest edge of a notch created by waves, and in underwater caves.

Biology and reproduction

The Lithophyllum frondosum has a three-stage life cycle. Apparently, it is not eaten by herbivores due to its rigid thallus.

Seasonality and distribution

The alga is perennial, and the thallus seems to live for several

years, although this has not been investigated in this region. The species is common in the north-eastern region of the Atlantic Ocean, and some claim that it is a Lessepsian species that entered the region from the Red Sea (the Indian Ocean).

Additional species

Extensive studies to catalogue the calcifying algae of the Eastern Mediterranean have not yet been done, since specialized knowledge is required for this task. Many species are identified according to photographs using electron- microscopy. In many cases, the calcium must first be melted using acid. Other species reported in the area include:

Lithophyllum byssoides (Lamarck) Foslie

Lithophyllum incrustans Philippi.