Metacercarial stages of digeneans were collected from decapod crustaceans inhabiting intertidal rocky zones in central Chile. The digeneans were identified through a molecular analysis based on the V4 region of the 18S ribosomal RNA gene. We analyzed 356 crustaceans belonging to 10 species, 115 intertidal fish belonging to 6 species, and 4 specimens of 1 coastal bird species. In total, 74.1% of crustaceans were parasitized with metacercariae. We found 1 species of Opecoelidae. This species showed low genetic divergence (0% and 0.1%) with adult digeneans found in intertidal fish and with the species Helicometrina labrisomi infesting a subtidal fish from northern Chile ( Labrisomus philippii ). Additionally, we found 2 species of Microphallidae, 1 closely related to Maritrema (1.3% genetic distance) and the other related to Microphallus (5% genetic distance). Therefore, our findings showed that the decapod crustaceans are relevant hosts in food webs from the southeastern Pacific coast. Furthermore, we found 5 species of crustaceans as second intermediate hosts for H. labrisomi and 2 species as secondary intermediate hosts for 2 Microphallidae, which contribute to elucidate parts of their life cycles through molecular markers and extended the host distribution of H. labrisomi in the southeastern Pacific coast.

This study analyzed the variation of the parasite infracommunities and their relationship with the diet and spatial distribution of the clingfish Sicyases sanguineus during its ontogeny. In total, 154 clingfish were collected from the intertidal and the upper subtidal zone of Pacific Ocean along the central Chilean coast. A wide range in body length (1.4–34.5 cm) was observed, including juvenile and adult specimens. Eleven parasite species were found in the clingfish, i.e., 2 Copepoda, 2 Hirudinea, 1 Monogenea, 5 Digenea, and 1 Cestoda. The prevalence, total abundance, Brillouin's diversity index, and the infracommunity species richness increased with fish body length. The parasite communities, the diet, and the spatial distribution changed during clingfish ontogeny, specifically between juveniles (<20 cm body length [BL]) and adults (>20 cm BL). When fish reached a 20-cm BL, a considerable increment in abundance and species richness of parasites was observed; this coincided with an increase in the number of prey items in the diet and with a change of the fish from the intertidal into the subtidal zone. Therefore, the ontogeny of S. sanguineus is important for the variation of parasite infracommunities, which also was associated with dietary and spatial distribution shifts of this fish.

A new species of nematode, Pseudodelphis chilensis n. sp., is described. This parasite was found in muscles of the pectoral fins of a blenniid fish, Scartichthys viridis , from central Chile. The new species differs from the other 2 described ( P. oligocotti Adamson and Roth, 1990 and P. limnicola Brugni and Viozzi, 2006 ) for its longer glandular esophagus and a small caecum at the beginning of the glandular esophagus; both characteristics are in males and females. In addition, the male of P. chilensis n. sp. does not have an adanal caudal papillae, and it has longer spicules than the other 2 species. This is the first Pseudodelphis species described for Chile and the second for South America.

The present study examines variation in parasite community characteristics of the toadfish Aphos porosus across sampling years. We analyzed and compared the species composition and numeric descriptors of the parasite infrapopulations and infracommunities in 101 fish collected during the springs of 1999, 2006, and 2007 from rocky intertidal ponds in El Tabo, central Chile. Parasites were found in 94.1% of specimens necropsied. In total 5,532 parasites were collected, representing 12 taxa, of which 7 were found in the 3 annual samples. The most prevalent and abundant parasites in the 3 sampling years were larval tetraphyllidean cestodes, followed by anisakid nematodes. The community descriptors of average richness and abundance varied significantly across the 3 yr, with the exception of parasite dominance. The parasite species composition and relative abundance showed low variability among years. A few parasite taxa ( Anisakis sp., Pseudoterranova sp., tetraphyllideans, and Clestobothrium crassiceps ) dominated the infracommunities of the toadfish; however, tetraphyllideans were the parasites that greatly varied over time. Consequently the parasite infracommunities of the toadfish were variable among years, with a low variation in parasite composition, but large differences in the aggregate descriptors.

In this study, we describe 2 new species of Ascarophis van Beneden, 1871 (Nematoda: Cystidicolidae), found in fishes from southern Chile. Ascarophis carvajali n. sp. was found in Austrolycus depressiceps and Patagonotothen cornucola , whereas Ascarophis draconi n. sp. was taken from Champsocephalus gunnari . These new Ascarophis species differ from other species in a combination of several morphometric and morphological characteristics. Although A. carvajali n. sp. was morphologically close to Ascarophis minuta , the new species has a larger ratio between glandular and muscular esophagus, filaments on both egg poles, and a shorter right spicule than A. minuta . Ascarophis draconi n. sp. was morphologically similar to Ascarophis adioryx and Ascarophis filiformis . However, A. adioryx has eggs without filaments, a smaller ratio between glandular and muscular esophagus length, and a smaller ratio between left and right spicule lengths in contrast to A. draconi n. sp., whereas A. filiformis has a shorter glandular esophagus and left spicule length than A. draconi n. sp. Only 1 Ascarophis species has been recorded in a single fish from Chile (i.e., Ascarophis sebastodis in Sebastes capensis ). Consequently, this study constitutes not only new species and records of Ascarophis in fishes from Chile, but also new records for the Pacific coast of South America.

The role of ecological and phylogenetic processes is fundamental to understanding how parasite communities are structured. However, for coral reef fishes, such information is almost nonexistent. In this study, we analyzed the structure of the parasite communities based on composition, richness, abundance, and biovolume of ecto- and endoparasites of 14 wrasse species (Labridae) from Lizard Island, Great Barrier Reef, Australia. We determine whether the structure of the parasite communities from these fishes was related to ecological characteristics (body size, abundance, swimming ability, and diet) and/or the phylogenetic relatedness of the hosts. We examined 264 fishes from which almost 37,000 individual parasites and 98 parasite categories (types and species) were recorded. Gnathiid and cestode larvae were the most prevalent and abundant parasites in most fishes. Mean richness, abundance, and biovolume of ectoparasites per fish species were positively correlated with host body size only after controlling for the host phylogeny, whereas no such correlation was found for endoparasites with any host variable. Because most ectoparasites have direct transmission, one possible explanation for this pattern is that increased space (host body size) may increase the colonization and recruitment of ectoparasites. However, endoparasites generally have indirect transmission that can be affected by many other variables, such as number of prey infected and rate of parasite transmission.

This study describes the community of all metazoan parasites from 14 individuals of thicklip wrasse, Hemigymnus melapterus , from Lizard Island, Australia. All fish were parasitized, and 4,649 parasite individuals were found. Twenty-six parasite species were identified although only 6 species were abundant and prevalent: gnathiid isopods, the copepod Hatschekia hemigymni , the digenean Callohelmis pichelinae , and 3 morphotypes of tetraphyllidean cestode larvae. We analyzed whether the body size and microhabitat of the parasites and size of the host affected understanding of the structure of the parasite community. We related the abundance, biovolume, and density of parasites with the host body size and analyzed the abundances and volumetric densities of some parasite species within microhabitats. Although the 2 most abundant species comprised 75% of all parasite individuals, 4 species, each in similar proportion, comprised 85% of the total biovolume. Although larger host individuals had higher richness, abundance, and biovolume of parasites than smaller individuals, overall parasite volumetric density actually decreased with the host body size. Moreover, parasites exhibited abundances and densities significantly different among microhabitats; some parasite species depended on the area available, whereas others selected a specific microhabitat. Parasite and habitat size exhibited interesting relationships that should be considered more frequently. Considerations of these parameters improve understanding of parasite community structure and how the parasites use their habitats.

Similascarophis (Cystidicolidae) n. gen. is proposed. In the mouth of specimens of this genus, submedial labia are absent and pseudolabia do not have any part projecting toward the central oral opening. These nematodes were obtained from the alimentary tract of 7 marine fish species along the coast of Chile: Bovichthys chilensis Regan, Eleginops maclovinus (Cuvier), Pinguipes chilensis (Valenciennes), Cilus gilberti (Abbott), Cheilodactylus variegatus Valenciennes, Girella laevifrons (Tschudi), and Graus nigra Philippi. Morphology and morphometry are compared between 2 new Similascarophis species: Similascarophis maulensis n. sp. and S. chilensis n. sp., which differ in the presence of sublabia and in the length of the glandular esophagus and left spicule. We also recorded Similascarophis sp. in 2 other host species, which showed some distinct proportional measurements, although these differences were not sufficiently clear to identify them as a new species.

A new acanthocephalan species, Spiracanthus bovichthys n. gen. n. sp., is described. Samples were taken from 26 marine fish species between 23 and 53°S of Chile. The parasite was found in the intestine of 6 species and only between 36 and 40° S, especially in those fish that prey on small crustaceans in the upper and sublittoral zone. The parasite was found in Bovichthys chilensis (Reagan), Auchenionchus variolosus (Valenciennes), Calliclinus genigutattus (Valenciennes), Sindoscopus australis (Fowler and Bean), Myxodes cristatus Valenciennes, and Gobiesox marmoratus (Jenyns). However, only the first species is a suitable host for the parasite as evidenced by the presence of mature females. This acanthocephalan belongs to Arhythmacanthidae, but it does not correspond to any genus described. Spiracanthus bovichthys is different in the number and spiralled distribution of its hooks in the proboscis. In the short proboscis, 3 groups of hooks are distinguished according to size, summing up to 150–190 hooks. The group of largest hooks are found in the apical part of the proboscis, and there are 10 diagonal rows of small hooks from the prebasal to basal proboscis. Its trunk is covered partially by small spines. Amphipod and isopods were the prey items shared among the host fish species and are the best candidates to be the intermediate hosts of S. bovichthys .

A new nematode belonging to the Cystidicolidae is described. Pseudascarophis genypteri n. sp. was found in the intestine of the red ling Genypterus chilensis, sampled off Talcahuano, Chile. It is distinguished from Ascarophis species mainly by the absence of cephalic papillae and of submedial and medial labia. The other species in the genus, Pseudascarophis kyphosi Ko, Margolis, and Machida, 1985 , found in Kyphosus cinerascens, and P. tropica ( Solov'eva, 1996 ), found in Parupeneus chrysopleuron, differed principally from P. genypteri in the form of pseudolabia, number of pre- and postanal papillae, and length of spicules.