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Genetic and morphological variations in two component populations of Raphidascaris ( Sprentascaris ) lanfrediae collected in the intestine of Geophagus argyrosticus and G. proximus (Cichlidae) from States of Pará and Amapá, Brazil, respectively, were explored for the first time. A phylogenetic study including two genes (18S and 28S of the rDNA) plus morphological and life history traits of “anisakid-related” nematodes (Anisakidae, Raphidascarididae) was also performed in order to clarify taxonomic and systematic issues related to these taxa. Gene alignments were subjected to maximum likelihood (ML) and Bayesian Inference (BI), and combined data of the genetic and morphological datasets was subjected to maximum parsimony (MP) analysis. Despite of the subtle differences in the morphology (mainly in male caudal papillae) and morphometry between specimens of R. ( S .) lanfrediae from the two different hosts and from the type material of the species, no genetic variation was found among representatives of the newly collected material. This find may represent an example of gene-environment interactions, similar to that recently observed for Raphidascaroides brasiliensis . Phylogenetic reconstructions indicated the paraphyly of Anisakidae represented by two subfamilies, i.e., Anisakinae and Contracaecinae and the monophyly of Raphidascarididae. Analysis of the combined datasets revealed that some morphological traits may represent apomorphic characters of Raphidascarididae and Anisakidae, whereas others are highly homoplastic and some may be interpreted with careful to avoid errors. The results support the premise that taxonomists should consider Anisakidae and Raphidascarididae as separate families, and only two subfamilies of Anisakidae, i.e., Anisakinae and Contracaecinae. [ABSTRACT FROM AUTHOR]

Here we provide a checklist of the crustacean species parasitizing both marine and freshwater fishes from Brazil. We list a total of 134 species of parasitic crustaceans associated with 205 species of fishes in Brazil. The data from this study added to the checklist of Copepoda in Brazilian fishes published in 2007 give a total of 251 species of parasitic crustaceans associated with 279 fish species currently known in Brazil. The majority of species of Crustacea listed as parasites of Brazilian fishes are Copepoda with 186 species registered. A total of 741 parasite-host associations were observed. Copepoda was the group with more host-parasite associations, totaling 419 associations. When comparing these data with those recorded for the fishes from other parasite hotspots of Neotropics (Mexico and Caribbean), it is possible to affirm that the fauna of parasitic crustaceans of Brazilian fishes is the richest in the region. [ABSTRACT FROM AUTHOR]

Abstract: Geographical distances between host populations are key determinants of how many parasite species they share. In principle, decay in similarity should also occur with increasing distance along any other dimension that characterizes some form of separation between communities. Here, we apply the biogeographical concept of distance decay in similarity to ontogenetic changes in the metazoan parasite communities of three species of marine fish from the Atlantic coast of South America. Using differences in body length between all possible pairs of size classes as measures of ontogenetic distances, we find that, using an index of similarity (Bray-Curtis) that takes into account the abundance of each parasite species, the similarity in parasite communities showed a very clear decay pattern; using an index (Jaccard) based on presence/absence of species only, we obtained slightly weaker but nevertheless similar patterns. As we predicted, the slope of the decay relationship was significantly steeper in the fish Cynoscion guatucupa, which goes through clear ontogenetic changes in diet and therefore in exposure to parasites, than in the other species, Engraulis anchoita and Micropogonias furnieri, which maintain a roughly similar diet throughout their lives. In addition, we found that for any given ontogenetic distance, i.e. for a given length difference between two size classes, the similarity in parasite communities was almost always higher if they were adult size classes, and almost always lower if they were juvenile size classes. This, combined with comparisons among individual fish within size classes, shows that parasite communities in juvenile fish are variable and subject to stochastic effects. We propose the distance decay approach as a rigorous and quantitative method to measure rates of community change as a function of host age, and for comparisons across host species to elucidate the role of host ecology in the development of parasite assemblages. [Copyright &y& Elsevier]

Parasite communities are generally believed to lie somewhere along the interactive-to-isolationist continuum, i.e. from rich assemblages of species with high colonisation rates in which interspecific interactions play an important structuring role, to species-poor assemblages where interactions are unlikely. This framework has become one of the paradigms of parasite community ecology. There is, however, no objective way of ranking a set of parasite communities in terms of the extent of interactivity among their constituent species. Here, we propose a simple index of interactivity based on the general likelihood of species co-occurrence, and thus on the potential for interactions, and we apply it to component communities of gastrointestinal helminth parasites from 37 species of marine fish hosts. The index essentially collapses several features of parasite communities thought to influence the degree of interactivity into a single number independent of the number of hosts examined or the total number of species in a component community. The range of values obtained here suggests that the potential interactivity in helminth communities of fish covers almost the full spectrum of possibilities, i.e. from isolationist to highly interactive communities. Although derived from presence/absence data only, the index correlates relatively strongly with the total parasite abundance per host, as well as the total prevalence of infection and the mean infracommunity richness. In other words, it captures properties of the community that influence interactivity. The use of the index in comparative studies may help in determining whether interactive helminth communities are, as widely believed, more common in endothermic vertebrate hosts than in fish hosts. [Copyright &y& Elsevier]

Tapeworms (Cestoda: Proteocephalidae) are the dominant component of communities of intestinal parasites in pimelodid and other catfishes (Siluriformes) from South America. Even though these parasites have been studied intensively over more than one century, molecular taxonomy and phylogenetics have questioned their morphology-based classification, thus raising doubts about the systematic value of traits commonly used to circumscribe individual taxa. In the present study, members of three morphologically well-characterized genera of proteocephalids from pimelodid (Hemisorubim platyrhynchos and Sorubim lima) and auchenipterid (Ageneiosus inermis) catfishes from the Paraná or Amazon River basins were subjected to DNA sequencing of the large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI). Phylogenetic analyses revealed the sister relationship between Manaosia bracodemoca and Mariauxiella piscatorum, and among Mariauxiella pimelodi and Ageneiella brevifilis. As a result, Mar. piscatorum and A. brevifilis are transferred to Manaosia and Mariauxiella, respectively, as Manaosia piscatorum n. comb. and Mariauxiella brevifilis n. comb., and the genus Ageneiella is suppressed. Diagnoses of Manaosia and Mariauxiella are amended. In addition, the present study revealed misidentification of tapeworms whose sequences are deposited in the GenBank database. [ABSTRACT FROM AUTHOR]

Proteocephalid tapeworms are the dominant group of endoparasites in siluriform catfishes in South America, but their interrelationships and actual diversity remain poorly understood. Molecular prospecting of proteocephalids found in pimelodid and other catfishes, especially in Pimelodus spp., along with thorough morphological evaluation, revealed high species diversity of these parasites. Using newly obtained sequences of the partial large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI), phylogenetic relationships of the cestodes of Pimelodus catfishes were assessed and a new genus, Pseudoendorchis gen. n., proposed to accommodate P. auchenipteri comb. n. (type species; formerly Endorchis auchenipteri), P. cristata sp. n. from Pimelodella cristata (Heptapteridae), P. felipei sp. n. from Pimelodus fur, P. souzalimae sp. n. from Pimelodus maculatus and another three putative new species. Members of the new genus can be readily distinguished from all known Neotropical proteocephalids by having a large Mehlis' gland, representing at least 18% of proglottid width, and the vagina always anterior to the cirrus‐sac. Moreover, all phylogenetic, species discovery and validation analyses support validity of Pseudoendorchis. Combining the lsrDNA + COI sequence data appeared to provide the best resolution in phylogenetic analyses, which may be useful to reduce the uncertainty of the interrelationships among Neotropical proteocephalids. [ABSTRACT FROM AUTHOR]

The diversity of parasite communities is mainly driven by evolutionary history, as well as the ecology of the host species. To test whether the diversity of the parasite community of four related Stromateidae (Pisces: Scombriformes) is related to evolutionary history (the host phylogeny) or the host's geographical distribution, we analyzed the metazoan parasite fauna of four species of fishes of this family, from the Pacific and Atlantic coasts of South America. Studied species were Peprilus snyderi (samples from Callao, Perú, and Antofagasta, Chile), Peprilus medius (Chorrillos, Perú), Peprilus paru (Rio de Janeiro, Brazil) and Stromateus stellatus (Talcahuano, Chile). Our multivariate analysis strongly suggests that the diversity of the parasite fauna of the studied fishes is driven mainly by the host's geographical distribution and not the host phylogeny. [ABSTRACT FROM AUTHOR]

Cucullanus pinnai has been divided in two subspecies (C. pinnai pinnai and C. pinnai pterodorasi) based on the morphology of oesophastome. While C. pinnai pinnai apparently shows low host specificity and broad geographic occurrence, with certain morphological variations, C. pinnai pterodorasi was reported once, parasitizing Pterodoras granulosus. We used an integrative taxonomic approach to evaluate whether or not populations of C. pinnai pinnai from Trychomycterus spegazzinii (Escoipe River, Argentina) and Pimelodus fur (Miranda River, Brazil), and of C. pinnai pterodorasi from Pterodoras granulosus (Miranda River, Brazil) are conspecific. Parasites were observed using light microscopy and genetically characterized based on partial sequences of the 18S and 28S rDNA, ITS1-5.8S-ITS2, and COI mtDNA. Phylogenies were reconstructed and the Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (bPTP), and Automatic Barcode Gap Discovery (ABGD) were used for species delimitation purposes. The present samples formed well-supported monophyletic assemblages, corroborating in part the results of morphological analyses; however, they grouped according to geographic origin. Species delimitation suggested conspecificity of C. pinnai pinnai with C. pinnai pterodorasi from Brazil; consequently, the morphology of oesophastome may be an intraspecific variation. Results also indicated that C. pinnai may represent a species complex as samples from Argentina were suggestive of an independent specific entity. However, definitive affirmations are premature, since there is no autapomorphy for separating C. pinnai from Brazil and Argentina and sampling was limited to three host species from two river basins. The phylogenetic reconstructions also confirmed the artificiality of some genera within Cucullanidae. [ABSTRACT FROM AUTHOR]

Using information from published articles, databases, and recent samples from the Brazilian coastal zone, a list of parasites of haemulid (grunts) fish known from the Neotropical and Nearctic regions was structured. A total of 231 species of parasites were listed totaling 775 records involving 48 hosts, distributed in 86 localities of the American Continent. Records were listed with information on hosts, habitat, distribution and new findings; a host-parasite list is also included herein. [ABSTRACT FROM AUTHOR]

A list of 108 species of metazoans parasites reported from penguins (Sphenisciformes) is provided, with information on their hosts, habitat and distribution. A total of 22 digeneans, 10 cestodes, 6 acanthocephalans, 31 nematodes, 15 mites and ticks, 25 insects have been found on 18 species of penguins, with most parasites reported from Eudyptula minor. A host-parasite list is also provided. [ABSTRACT FROM AUTHOR]

Using information from all published reports and data collected during several parasitological surveys between April 2003 and September 2009, a checklist of the parasites of fishes from Guandu River, southeastern of Brazil was generated. A total of 85 parasite species, 54 named species (1 Acanthocephala, 1 Cestoda, 2 Crustacea, 13 Digenea, 11 Nematoda, 23 Monogenea and 3 Myxozoa) and 31 undetermined species (3 Acanthocephala, 2 Cestoda, 1 Crustacea, 8 Digenea, 8 Nematoda, 4 Hirudinea, 3 Monogenea and 2 Myxozoa) in 21 fish host species from Guandu River, were listed in the current study, including 36 new locality records and 36 new host records. Also, a host-parasite list is included herein. [ABSTRACT FROM AUTHOR]

Abstract: Patterns of distance decay in similarity among communities of the fish Pinguipes brasilianus (Teleostei: Pinguipedidae) from five areas in the southwestern Atlantic were investigated to determine whether the rate of decay varied depending on the community level or the parasite guild analyzed (ectoparasites, adult endoparasites and larval endoparasites). Similarities in species composition were computed at both the component community and infracommunity levels. Similarity indices were calculated between all possible pairs of assemblages from different zones. Infracommunity similarity values between and within host populations were averaged. Significance of linear regressions for similarity values against distance was assessed using randomization tests. Different patterns were observed for each guild, and similarity among infracommunities within host populations varied accordingly. Decay in similarity over distance was recorded for most communities. The slopes differed significantly between infracommunities and component communities in all cases, and stronger decay was always observed for infracommunities. Different geographical patterns in parasite communities were a consequence of variability in parasite availability in the different regions, modulated by oceanographic conditions, as well as variation among species in terms of host specificity and life-cycles strategies. Infracommunities showed a stronger effect of distance than component communities, probably due to the influence of short term and local variability of oceanographic conditions. [Copyright &y& Elsevier]

Parasite communities are similar to free‐living communities; decay of similarity over geographic distance, theory of island biogeography, species–area relationships and nestedness have been documented in both communities. Ecological succession has been studied in free‐living communities but has rarely been examined in parasite communities. We use seriation with replication to test the hypothesis that succession of parasite community structure is deterministic, thus developing throughout consecutive changes along the fish ontogeny, via a seriated pattern. 12 306 marine fishes (95 species) were studied. In 40 species, a seriated pattern was detected; 25 had a tendency towards a seriated pattern, and for 31 species, succession was at random. Age‐classes for each host species explained deterministic successional patterns for whole parasite communities and ectoparasites. Richness and number of age‐classes explained this pattern for endoparasites. Seriated successional pattern was evident for parasite communities of long‐lived marine fish, indicating that parasite communities follow sequential changes over time, like many free‐living communities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Parasites allowed distinguishing two stocks of Umbrina canosai. • Migrations between south Brazil and Argentina were confirmed for the Southern stock. • A set of suitable biological tags was identified to be applicable in future studies. • Size of U. canosai is relevant in determining the structure of parasite assemblages. Abstract The Argentine croaker Umbrina canosai (Sciaenidae) is a demersal fish distributed along the coasts of central Brazil, Uruguay and northern Argentina. In recent years, an increasing impact of commercial fishing has been reported, representing a high risk of collapse for this resource and enhancing the need of knowledge on its population structure. In the southwestern Atlantic fish parasites have already been demonstrated to be useful as biological tags for such purposes in other resources and are, here, analyzed to delimit the stocks of U. canosai and confirm its migratory route between Brazil and Argentina. A total of 193 Argentine croakers, distributed in six samples from five different localities, were examined for metazoan parasites. Umbrina canosai harboured 28 parasite taxa among which long-lived larvae of Grillotia carvajalregorum , Corynosoma australe and Hysterothylacium sp., and the adult monogenean, Nicolasia canosorum , were the most prevalent. Host size was related to both diversity and structure of parasite infracommunities in the whole sample, but no effect of fish sex was detected. The multivariate analyses, at both infracommunity and component community levels, showed clear geographic patterns with fish from Rio de Janeiro differentiated from their southern counterparts, confirming the presence of two discrete stocks. The results also evidenced the homogeneity of samples caught in southern Brazil and Northern Argentina, regardless of the long distances separating them, confirming the existence of a single stock with seasonal migrations between southern Brazil and northern Argentina. The information on the stock structure and migratory pathways of U. canosai represents a first step to the implementation of measures for a sustainable management of this important fishery resource. [ABSTRACT FROM AUTHOR]

A new genus and species of monogenean belonging to Hexabothriidae, Hypanocotyle bullardi n. gen. n. sp., is described based on specimens collected from the gill filaments of the diamond stingray, Hypanus dipterurus (Jordan et Gilbert) (Myliobatiformes: Dasyatidae), a demersal chondrichthyan collected off the coast of Callao, Peru. Hypanocotyle n. gen. has the following combination of diagnostic features that differentiate it from other hexabothriid genera: haptor symmetrical; vasa efferentia having proximal (narrow, with thin glandular wall) and distal (expanded, interlaced, with thick glandular wall) portions, joining medially to form vas deferens; vas deferens having proximal (expanded, sinuous, with thick glandular wall) and distal (narrow, strongly sinuous, with thin glandular wall) portions; male copulatory organ unarmed, proximal portion slightly sinuous and tube-like, distal portion funnel-shaped; prostatic glands present, distributed around of the MCO; seminal receptacle present; ootype lacking longitudinal rows of large cells (no oötype côtelé); vaginae parallel, with well-differentiated proximal (glandular, narrow, tube-like, slightly sinuous) and distal (musculoglandular, convoluted) portions; gland cells surrounding the vaginal duct along the entire length of distal portion, densely clustered in middle portion; uterine eggs with 2 elongate filaments. Phylogenetic reconstructions by maximum-likelihood method, based on newly obtained partial 18S and 28S sequences, shows that H . bullardi n. gen. is included within the family Hexabothriidae, order Diclybothriidea. This is the second hexabothriid genus recorded from a diamond stingray (Dasyatidae), and the fourth hexabothriid species recorded from Peru. A key to hexabothriid genera is provided. [ABSTRACT FROM AUTHOR]

With the aim of evaluating the utility of marine parasites as indicators of ecotonal regions in the marine environment, we analysed data on assemblages of long-lived larval parasites of Zenopsis conchifer inhabiting the region of convergence of three masses of water in the southwestern Atlantic Oceans. These masses of water with different origins are expected to affect the structure of parasite communities by acting as sources of infective stages of helminth species typical of adjacent zoogeographical regions. Multivariate analyses at both infracommunity and component community levels, including data of four other species recognised as harbouring parasite assemblages representatives of these zoogeographical regions, were carried out to corroborate the existence of repeatable distribution patterns and to provide further evidence of the utility of parasites as zoogeographic indicators in the region. Results showed a tight correspondence with the existing zoogeographical classification in the study region, namely two zoogeographical provinces, one of which is subdivided into two districts demonstrating the ecotonal nature of parasite assemblages from the convergence region, which were characterised by a species rich component community but depauperate and heterogeneous infracommunities. The borders of biological communities have been suggested as priority areas for conservation where a fully functioning ecosystem can be protected and parasite communities can be considered as reliable indicators to define such transitional regions. [ABSTRACT FROM AUTHOR]

Three stocks of the flounder Paralichthys isosceles Jordan, 1861 were identified in the southwestern Atlantic by using their parasites as biological markers. Comparisons (pemutational multivariate analyses of variance and canonical analysis of principal coordinates) of 78 flounders caught simultaneously at two close localities in Brazil (Cabo Frio and Niteroi) and previously published data of 51 fish from Argentina (Necochea) allowed testing the value of parasite tags as discriminators at both small and large spatial scales. A total of 5925 metazoan parasites belonging to 17 species were found in Brazilian samples. Parasite assemblages varied across localities in terms of species richness and presence and abundance of individual species. Multivariate analyses of presence and abundance of long-lived parasites resulted in clear dissimilarity patterns across all samples. Significant differences were also observed when the entire parasite assemblages were compared between both Brazilian samples. The best discriminator species at both spatial scales were represented by unspecific parasites, broadly distributed among fish species in the region. These indicator species apparently display recurrent spatial patterns across host species, being therefore expected to serve as suitable tags for population studies of other resources. Parasites constitute valuable tools to be included in further holistic stock identification studies, which may eventually allow proactive mitigation and conservation strategies for many short scale artisanal fisheries in the southwestern Atlantic coasts, which are facing severe risks of overexploitation and collapse. [ABSTRACT FROM AUTHOR]

The use of the complex network approach to study host–parasite interactions has helped to improve the understanding of the structure and dynamics of ecological communities. In this study, this network approach is applied to evaluate the patterns of organisation and structure of interactions in a fish-parasite network of a neotropical Atlantic Forest river. The network includes 20 fish species and 73 metazoan parasite species collected from the Guandu River, Rio de Janeiro State, Brazil. According to the usual measures in studies of networks, the organisation of the network was evaluated using measures of host susceptibility, parasite dependence, interaction asymmetry, species strength and complementary specialisation of each species as well as the network. The network structure was evaluated using connectance, nestedness and modularity measures. Host susceptibility typically presented low values, whereas parasite dependence was high. The asymmetry and species strength were correlated with host taxonomy but not with parasite taxonomy. Differences among parasite taxonomic groups in the complementary specialisation of each species on hosts were also observed. However, the complementary specialisation and species strength values were not correlated. The network had a high complementary specialisation, low connectance and nestedness, and high modularity, thus indicating variability in the roles of species in the network organisation and the expected presence of many specialist species. [ABSTRACT FROM AUTHOR]

Background: The nematode Angiostrongylus cantonensis is a zoonotic parasite and the most important cause of eosinophilic meningitis worldwide in humans. In Brazil, this disease has been reported in the states of Espírito Santo and Pernambuco. The parasite has been detected in the naturally infected intermediate host, in the states of Rio de Janeiro, Pernambuco and Santa Catarina. The murid Rattus norvegicus R. rattus were recently reported to be naturally infected in Brazil. In this study, we conducted a two-year investigation of the dissemination pattern of A. cantonensis in R. norvegicus in an urban area of Rio de Janeiro state, Brazil, and examined the influence of seasonality, year, host weight and host gender on parasitological parameters of A. cantonensis in rats. Methods: The study was conducted in an area of Trindade, São Gonçalo municipality, Rio de Janeiro, Brazil. Prevalence of infected rats, intensity and abundance of A. cantonensis were calculated, and generalized linear models were created and compared to verify the contribution of host gender, host weight, year and seasonality to the variations in A. cantonensis abundance and prevalence in rats. Results: The prevalence of A. cantonensis infection was stable during the rainy (71%, CI 58.9- 81.6) and dry seasons (71%, CI 57.9-80.8) and was higher in older rats and in females. Seasonality, host weight (used as a proxy of animal age) and gender were all contributing factors to variation in parasite abundance, with females and heavier (older) animals showing larger abundance of parasites, and extreme values of parasite abundance being more frequent in the dry season. Conclusions: The high prevalence of this parasite throughout the study suggests that its transmission is stable and that conditions are adequate for the spread of the parasite to previously unaffected areas. Dispersion of the parasite to new areas may be mediated by males that tend to have larger dispersal ability, while females may be more important for maintaining the parasite on a local scale due to their higher prevalence and abundance of infection. A multidisciplinary approach considering the ecological distribution of the rats and intermediate hosts, as well as environmental features is required to further understand the dynamics of angiostrongyliasis. [ABSTRACT FROM AUTHOR]

Interspecific variation in parasite species richness among host species has generated much empirical research. As in comparisons among geographical areas, controlling for variation in host body size is crucial because host size determines resource availability. Recent developments in the use of species-area relationships (SARs) to detect hotspots of biodiversity provide a powerful way to control for host body size, and to identify 'hot' and 'cold hosts' of parasite diversity, i.e. hosts with more or fewer parasites than expected from their size. Applying SAR modelling to six large datasets on parasite species richness in vertebrates, we search for hot and cold hosts and assess the effect of other ecological variables on the probability that a host species is hot/cold taking body size (and sampling effort) into account. Five non-sigmoid SAR models were fitted to the data by optimisation; their relative likelihood was evaluated using the Bayesian information criterion, before deriving an averaged SAR function. Overall, the fit between the five SAR models and the actual data was poor; there was substantial uncertainty surrounding the fitted models, and the best model differed among the six datasets. These results show that host body size is not a strong or consistent determinant of parasite species richness across taxa. Hotspots were defined as host species lying above the upper limit of the 80% confidence interval of the averaged SAR, and coldspots as species lying below its lower limit. Our analyses revealed (1) no apparent effect of specific ecological factors (i.e. water temperature, mean depth range, latitude or population density) on the likelihood of a host species being a hot or coldspot; (2) evidence of phylogenetic clustering, i.e. hosts from certain families are more likely to be hotspots (or coldspots) than other species, independently of body size. These findings suggest that host phylogeny may sometimes outweigh specific host ecological traits as a predictor of whether or not a host species harbours more (or fewer) parasite species than expected for its size. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented about incidence of Angiostrongyliasis in Rio de Janeiro, Brazil.