By combining an examination of stomach contents yielding a snapshot of the most recent trophic niche and the structure of parasite communities reflecting a long-term feeding niche, this study aimed at gaining more comprehensive information on the role of the small-sized deep-water velvet belly lantern shark Etmopterus spinax in the local food webs of the Galicia Bank and the canyon and valley system of the Avilés Canyon, which have been both proposed for inclusion in the Natura 2000 network of protected areas. As far as is known, this study provides the first comparative parasite infracommunity data for a deep-sea shark species. Component parasite communities in E. spinax were relatively rich, whereas the infracommunities were rather depauperate, with similar low diversity at both localities. The significant differences in the composition and structure of both parasite communities and prey assemblages indicate differential effects of the two deep-sea ecosystems on both long-term and most recent trophic niches of E. spinax. These results underline the importance of the use of multivariate analyses for the assessment of geographical variation in shark populations based on parasites and diet data.

Marine protected areas are considered a useful tool to preserve and recover the biodiversity of ecosystems. It is suggested that fisheries not only affect populations of target and bycatch species but also their parasite communities. Parasites can indicate fishery effects on host species and also on the whole local community, but the effects of fisheries and protection measures on parasite communities are relatively unknown. This study analyses parasite communities of the white seabream Diplodus sargus sargus in order to assess potential effects exerted by protection measures within and by fisheries outside a reserve in the western Mediterranean Sea. This small scale analysis offered the opportunity to study different degrees of fishery effects on parasite infracommunities, without considering climatic effects as an additional factor. Parasite infracommunities of fishes from the no-take zone (NTZ) differed in their composition and structure compared with areas completely or partially open to fisheries. The detected spatial differences in the infracommunities derived from generalist parasites and varied slightly between transmission strategies. Monoxenous parasites were richer and more diverse in both fished areas, but more abundant in the no-take, whereas richness and abundance of heteroxenous parasites were higher for the NTZ. In addition to host body size as one factor explaining these spatial variations, differences within parasite infracommunities between the areas may also be linked to increased host densities and habitat quality since the implementation of the NTZ and its protection measures.

A new cucullanid, Dichelyne (Cucullanellus) romani n. sp. (Nematoda: Cucullanidae), is described from the digestive tract of two notacanthid fishes, Notacanthus chemnitzii Bloch and N. bonaparte Risso (Notacanthiformes: Notacanthidae), from the Northeast Atlantic and Western Mediterranean. The presence of a precloacal sucker and ten pairs of caudal papillae in males allocates it to the subgenus Cucullanellus Törnquist, 1931. The new species differs from other members of this subgenus in its larger body size, smaller spicule/body length ratio, the distribution of caudal papillae, and the position of deirids and excretory pore. Both notacanthid fishes act as definitive hosts with slightly larger nematode specimens detected in N. chemnitzii. A wide intraspecific variability was found in the distribution of caudal papillae, and in some specimens the position of deirids, excretory pore and length of intestinal caecum also varied. A complete list of all assigned species of the subgenus Cucullanellus is presented and discussed as there are several uncertainties regarding the validity and synonymy of some species. This is the first species of Dichelyne Jägerskiöld, 1902 in a notacanthid fish and one of the only two records in deep-sea fish species.

Three snake eels (Ophichthidae) were found in three common pandoras (Pagellus erythrinus) from the north-western Mediterranean: two in the stomach and one embedded in the body cavity. This incidence corroborates previous records of snake eels found within fish. The role of the eels as possible prey, parasites or pseudoparasites is briefly discussed.

A new aporocotylid, Skoulekia erythrini n. sp., is described from the heart, cephalic kidney and gill blood vessels of the common pandora Pagellus erythrinus (L.) collected from several localities of the western Mediterranean off Spain. The new species differs from the type- and only species of the genus, S. meningialis Alama-Bermejo, Montero, Raga & Holzer, 2011 in possessing a symmetrical body (vs laterally curved), short tegumental spines (3-4 vs 7-10 µm) without hooked ends, diffuse (vs conspicuous) oesophageal gland-cells, a relatively longer oesophagus, a testis that is shorter in relation to body length and a much smaller seminal vesicle (17-34 × 10-26 vs 33-101 × 27-97 μm). Elongated ellipsoidal eggs of S. erythrini n. sp. were found trapped in gill vessels in histological sections. Phylogenetic analyses based on partial 28S rDNA and ITS2 sequences supported the placement of the new species within Skoulekia and the close relationships of this genus with Psettarium Goto & Ozaki, 1929 and Pearsonellum Overstreet & Køie, 1986. Skoulekia meningialis is described from a new sparid host, Diplodus puntazzo (Walbaum), collected off Santa Pola, Spain. The new morphological data for the two Skoulekia spp. and a re-examination of three paratypes of S. meningialis pinpointed features amending both the description of S. meningialis and the generic diagnosis of Skoulekia.