On the presence of the rhodophyte Plocamium raphelisianum (Plocamiales, Florideophyceae) on southern European coasts

Abstract

The presence of Plocamium raphelisianum P. Dangeard, originally described from the Moroccan coasts, along most of the shores of the Iberian Peninsula is highlighted in this paper. A detailed description of this poorly studied species is presented, showing its differentiation from P. cartilagineum (Linnaeus) P. Dixon, a close congeneric species with which it has been frequently mistaken. The morphological variability of the species according to local environmental conditions is discussed. Salient traits in P. raphelisianum are its repeatedly pinnate ramification with series of (2)3 ramuli and its purplish red colour with a bluish iridescence when submerged in seawater. Male gametophytes are described for the first time as well as the various habitats where this species can be frequently found. Most of the previous records of P. raphelisianum from the Iberian Peninsula were revised and confirmed enlarging notably its known area of distribution from the Atlantic coast of Guipuzcoa to the Mediterranean shores of Valencia, and also including the first report of the species from the Canary Islands. Finally, the relationship between P. raphelisianum and P. suhrii Kützing, a seemingly close congeneric species from South Africa is discussed.

Keywords

• plocamium
• plocamium raphelisianum
• plocamium suhrii
• morphology
• ecology
• distribution
• iberian peninsula
• canary islands