Littoral pycnogonids from the Chafarinas Islands (Alboran Sea, western Mediterranean)

A faunistic, ecological and zoogeographical study has been carried out on pycnogonids from the Chafarinas Islands, located off the north Mediterranean coast of Morocco. Eight perpendicular transects off the coast line have been prospected, collecting 30 samples in different substrata. Each sample was obtained by scraping of a 25 x 25 cm area. A total of 710 specimens belonging to 21 species, 7 genera and 4 families, have been identified. Ammothella longioculata from the Iberian Peninsula and Trygaeus communis from southern Spain are recorded for the first time. Halopteris scoparia is the richest substratum in pycnogonids. The taxocoenosis is characterised by the following species sorted by decreasing occurrence: Callipallene tiberi, Achelia echinata, A. vulgaris, C. spectrum and Ammothella longipes. The family Callipallenidae is the most abundant (49 % of the specimens) and Ammotheidae the richest in species (10 species). Finally, the bathymetric distribution of specimens found in H. scoparia is analysed and the geographical distribution of species recorded from these islands is typical of the Mediterranean.