Larval nematodes (Spiruroidea : Cystidicolidae) in Octopus vulgaris (Mollusca : Cephalopoda : Octopodidae) from the northeastern Atlantic Ocean

Larval nematode parasites (Spiruroidea: Cystidicolidae) are recorded for th e. first time in Octopus vulgaris Cuvier, 1797 in the northeastern Atlantic Ocean. Prevalence was 16% and mean intensity was 1.46 worms/host. Body len gth of larval nematodes ranges from 8.3 to 9.3 mm, with a distance from the anterior end to nerve ring from 187.5 to 200 mu m, and to excretory pore 1 94.6-350 mu m. Anatomical characteristics, such as deirid, nerve ring, ceph alic alae, excretory pore, pseudolabia amphids, sclerotized protuberance, a nd anus, examined using light microscopy (LM) or scanning electron microsco py (SEM), are illustrated. The nematode was designed as a cystidicolid "Typ e A" larva. The hemocytic infiltration present in the host tissue around th e nematode capsule and the mechanical compression in the infected organs de note the pathogenicity of this nematode. In the study area, O. vulgaris may play the role of an intermediate or paratenic host in the nematode life cy cle.