Two species of deep-sea skates, Amblyraja frerichsi and Notoraja martinezi, are reported for the first time in Peruvian waters, representing the first record of their respective genera from the country. Earlier, A. frerichsi was known from both the southwestern Atlantic (off Brazil, Uruguay, and Argentina) and southeastern Pacific (off Chile), while N. martinezi was known from Costa Rica to Ecuador in the eastern-central and southeastern Pacific. This study contributes to the limited knowledge of deep-sea fish diversity along the South American west coast, and stresses the need of further taxonomic research in the region, particularly in light of the ecological importance of this group of fishes in marine ecosystems and its conservation state worldwide.

A new species of Loimopapillosum Hargis, 1955 is described based on specimens collected from the gills of the diamond stingray, Hypanus dipterurus (Jordan & Gilbert, 1880) (Myliobatiformes: Dasyatidae) captured off Puerto Pizarro, Tumbes Region, northern Peru. Loimopapillosum pascuali n. sp. is distinguished mainly from the type and only species, Loimopapillosum dasyatis Hargis, 1955, by its funnel-shaped male copulatory organ, with an asymmetrical base; the superficial root of the anchor with distal knobs; the deep root of the anchor with a constriction at its base; a single testis; and the number of head organs. Available sequences for members of Monocotylidae in the GenBank as well as partial sequences for the gene 28S and 18S ribosomal DNA from L. pascuali n. sp. were included in phylogenetic analyses, suggesting that Loimoinae (represented in this study by L. pascuali n. sp. and Loimosina sp.) is nested within the Monocotylidae Taschenberg, 1879. Therefore, we confirm the rejection of Loimoidae Price, 1936 and its reincorporation as a subfamily of Monocotylidae, as previously suggested. Loimopapillosum pascuali n. sp. represents the first species of this genus in South America.

Based on data from 151 underwater surveys (scuba) between 2002 and 2007, the present study assessed the reef fish fauna from a scarcely known region on the north-eastern Brazilian coast (Ceará State). A checklist of 179 taxa is provided and the zoogeographic patterns are analysed and discussed, including six other localities. Based only on assemblage composition, the reef fish fauna from Ceará showed a strong resemblance (73%) with the reefs of Risca do Zumbi (RN) and Paraiba (PB). The data from the visual censuses including abundance values corroborate the evaluation based only on composition and suggest ecological factors as the main drivers of the fish assemblages in the region.

Myxosporeans are among the most common parasites of marine fish. Their economic importance is mainly as pathogens of both wild and farmed fish, but they have also been used as biological tags in population studies of their fish hosts. Here we review the literature and show the distribution of different families of Myxosporea infecting marine fishes in the world's oceans – the North Atlantic, South Atlantic, North Pacific, South Pacific and Indian. We also analyse their distribution in different orders of marine fishes. New families, genera and species of marine Myxosporea are continually being described and many more await description. Some regions, in particular the North Atlantic, have been more thoroughly investigated than others, so the analyses we present may not reflect the true distributions and we acknowledge that these may change considerably as other regions are investigated more fully. The distribution of myxosporean families in different taxonomic groups of marine fishes can indicate phylogenetic relationships between parasite and host and suggest the origins of different myxosporean taxa. We present some examples, while recognizing that new molecular information on phylogenetic relationships within the Myxozoa will lead to major changes in classification.

National and international policies have encouraged the establishment of a representative network of marine protected areas (MPAs) in South Africa, with the aim of protecting marine biodiversity. The extent to which these marine and estuarine protected areas (EPAs) represent marine fish species and communities was assessed by comparing their species compositions with those of exploited areas, as sampled using four fishing techniques. Seven hundred fish species were sampled, representing one-third of South Africa's marine fishes. MPAs in coastal habitats scored c. 40% on the Bray-Curtis measure of similarity for species representativeness, but this score declined markedly for offshore ‘trawlable’ fishing grounds. The combined effects of sampling error, temporal variation and the effects of fishing on relative abundance suggest that 80% similarity would be the maximum achieveable. Forty-nine per cent of all fish species that were recorded were found in the 14 MPAs sampled. Redundancy in the MPA network was low, with fish species most commonly being represented in only one MPA or absent. There was greater redundancy in the 33 EPAs, with 40% of species being found in two or more EPAs, but many of these estuaries were adjacent to each other and embedded in large MPAs. Deep water fish communities (>80 m deep) and communities located on the west and south-east coasts of South Africa were most poorly represented by MPAs. Routine fishery surveys provide a robust and repeatable opportunity to assess species representativeness in MPAs, and the method used could form the basis of an operational definition of ‘representative’. In contrast to an assessment based on presence-absence data, this analysis of quantitative data presents a more pessimistic assessment of protection.

Nested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a ‘Nestedness’ programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33–66% of analysed ectoparasite assemblages, and 25–75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness.