MORPHOLOGICAL VARIABILITY IN EUNICE-VITTATA (CHIAJE, 1828) (POLYCHAETA, EUNICIDAE) IN THE RIA-DE-FERROL (GALICIA, NW SPAIN)

Various morphological measurements were made on a total of 197 specime ns of Eunice vittata from Ria de Ferrol (Galicia, NW Spain). For each specimen the morphological features studied were: first setiger with s ubacicular hooks, uniramous branchiae, and biramous branchiae; width o f the 10th setiger; and, for entire specimens, preserved body length a nd total number of setigers. Multivariate analysis (PCA) indicates tha t body size explains the variability of width, length, number of setig ers and first occurrence of subacicular hooks. Occurrence of biramous branchiae, while showing a correlation with other varying features, is highly variable, associated with size-independent factors. The relati ve growth of E. vittata is allometric. Increase in number of setigers prevails in the initial growth stages, but gradually the increase in s ize of existing segments contributes more and more to the increase in body size, first by the increase of segment length and finally by the increase of segment width.