Phaeophyta, Brown Algae
Dictyopteris membranacea (Stackhouse) Batters
Phaeophyta, Order: Dictyotales; Family: Dictyotaceae.
The scientific name of the genus refers to the branching characteristics of the thallus, which are also characteristic of the family and the order. Membranacea refers to the membranes at the edges of the plant’s central axis. This is an accepted synonym for Dictyopteris ambigua (Clemente) Cremades.
The Dictyopteris membranacea is an erect brown alga that is easily identified. It is made of elongated stipes of thin membranous thalli at the centre of which a central axis runs prominently. The stipes are rounded at the edges, but some deteriorate with maturity. The branching is dichotomous and irregular. New branches can be seen regenerating at the bottom of the alga, near its holdfast. Dark spots can be seen upon the algal surface, especially on the side from which the vein protrudes, which are actually clusters of sterile hair.
The alga reaches a length of 30 cm, more or less, but most individuals found at sea do not exceed 10 cm. The stipes are several millimeters to 1 cm in width.
The alga has a warm brown hue.
The central vein, which is dark and prominent, enables simple identification of the species. The ‘leaves’ are more or less uniform in width throughout their length.
The Dictyopteris membranacea can be found in the subtidal zone, in potholes and rocks that face the sea. Individuals have been found at depths between 30-50 m.
Biology and reproduction
The Dictyopteris membranacea develops through a row of apical cells found at the top of each branch. The branches are made of 2-3 layers of cells although, near the vein, a larger number of layers can be seen. The reproductive organs also develop near the vein, but fertile individuals are hard to find. The sexual generation and the asexual generation are similar in shape.
Seasonality and distribution
The Dictyopteris membranacea is quite common during the winter and summer months, but becomes scarcer during the autumn. The species’ global distribution includes the Mediterranean, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean.
Another species of Dictyopteris: Dictyopteris polypodioides (De Candolle) Lamouroux. is mentioned in literature from this area, but this may be a synonym for Dictyopteris membranacea (Stackhouse) Batters. Another accepted synonym for Dictyopteris membranacea is Dictyopteris ambigua (Clemente) Cremades.
The Dictyopteris is considered to be a tasty alga, and many species of animals consume it. It is a popular ingredient in Hawaiian cuisine.