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Phaeophyta, Brown Algae

Spatoglossum solieri (Chauvin and Montagne) Kutzing

Phaeophyta,  Order: Dictyotales; Family: Dictyotaceae.


Spatoglossum refers to the colour and texture of the alga, which resembles a tongue. Solieri, is dedicated to the French researcher, Solieri.


The Spatoglossum solieri is a large, flattened, dark brown alga, with a thick, coarse thallus. Often a budding growth can be discerned on a mature branch. The thallus tends to divide into opposing rays, especially in younger individuals. The edges of the thallus seem torn and lobed. Older individuals are often covered in large numbers of epiphytes.


The alga reaches a height of 20 cm and more. The

Spatoglossum is longer than it is wide. Its thallus is several centimeters wide.


The Spatoglossum solieri is dark brown. When extracted from the water it turns dark green.

Special features

A unique feature of the Spatoglossum solieri is its brown colour that turns to green upon exposure to the air.


The alga is to be found in the subtidal zone, in potholes. Some have also been found in depths of over 30 m. Species found in the depths are smaller and more delicate than those common in the upper regions.

Biology and reproduction

The Spatoglossum solieri is apparently a migrant species  that arrived from the Red Sea following the opening of the Suez Canal. A dismembered thallus can retain its vitality for extended periods. The reproductive system resembles that of other family members. Reproductive spores (tetraspores) appear on both sides of the ‘leaf’.

Seasonality and distribution

The alga can be found along the shore throughout nearly the entire year. During some seasons the population shrinks, but soon afterwards, massive germination can be observed. Global distribution covers the Mediterranean and the Atlantic Ocean.

Additional species

The Spatoglossum asperum J. Agardh has also been reported in the region. It is difficult to determine if these are two separate species or it is an error in identification.

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