Parasitism with Protozoa and Monogeneans in Fish from the Natural Waters of Romania.

Parasitism by protozoa and monogenean flatworms in freshwater fish from Romania was studied by collecting and examining samples from two major river systems there: 183 fish from 17 species from the Olt River and its tributaries; and 155 fish from 16 species from the Mureș River and its tributary, Târnava Mare. The average rates of parasitism in the samples from the two rivers and their tributaries were as follows: Ichthyiophthirius multifiliis (2%), Trichodina spp. (21%), Apiosoma spp. (18%), Mixobolus spp. (8%), Dactylogyrus spp. (9%), and Gyrodactylus spp. (10%). The number of parasite species varied from one river to another. I. multifiliis was found in only 3 fish species, Trichodina spp. in 13 species, Glosatella spp. in 6 species, and Mixobollus spp., Dactylogyrus spp., and Gyrodactylus spp. in 7 different species each. The highest number of parasite species (six) were identified in the European chub (Squalius cephalus) and schneider (Alburnoides bipunctatus), which seem more susceptible to parasitic infections. The aquatic environment of these rivers may represent a source of parasites for fish from neighboring countries through which these rivers pass.

Integrative taxonomy of metazoan parasites of the bluntnose sixgill shark Hexanchus griseus (Bonnaterre, 1788) in the Mediterranean Sea, with the resurrection of Grillotia acanthoscolex Rees, 1944 (Cestoda: Trypanorhyncha).

Appropriate diagnoses of parasites of apex marine predators are crucial to understand their biodiversity, host specificity, biogeography, and life cycles. Such diagnoses are also informative of ecological and biological characteristics of both host and environment in which the hosts and their parasites live. We here (i) investigate the parasite fauna of a bluntnose sixgill shark Hexanchus griseus (Bonnaterre, 1788) obtained from the Gulf of Naples (Tyrrhenian Sea), (ii) characterize molecularly all its metazoan parasites, and (iii) resurrect and report the main morphological features and phylogenetic position of Grillotia acanthoscolex, a cestode species previously synonymized with Grillotia adenoplusia. A rich parasite fauna represented by eight different taxa was found, including two monogeneans (Protocotyle grisea and Protocotyle taschenbergi), one digenean (Otodistomum veliporum), four cestodes (Crossobothrium dohrnii, Clistobothrium sp., G. acanthoscolex, and G. adenoplusia), and one copepod (Protodactylina pamelae). Sequencing of these samples accounts for an important molecular baseline to widen the knowledge on the parasitic fauna of bluntnose sixgill sharks worldwide and to reconstruct their correct food chains. The bluntnose sixgill shark was found to be a definitive host for all endoparasites found here, confirming that it occupies an apex trophic level in the Mediterranean Sea. The taxa composition of the trophic parasite fauna confirms that the bluntnose sixgill shark mostly feeds on teleost fish species. However, the occurrence of two phillobothrid cestodes (C. dohrnii and Clistobothrium sp.) suggests that it also feeds on squids. Finally, we emphasize the importance of using integrative taxonomic approaches in the study of parasites from definitive and intermediate hosts to elucidate biology and ecology of taxa generally understudied in the Mediterranean Sea.

Dactylogyrids (Platyhelminthes, Monogenea) from the gill lamellae of doradids (Siluriformes) with description of five new species of Cosmetocleithrum and new geographical distribution for known species from the Neotropical Region, Brazil.

Five new species of Cosmetocleithrum were described parasitizing the gill filaments of neotropical doradid fishes. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. and Cosmetocleithrum ludovicense n. sp. are described from Platydoras brachylecis from a market-place of São Luís, State of Maranhão, Brazil. Cosmetocleithrum sacciforme n. sp. and Cosmetocleithrum basicomplexum n. sp. are described from Oxydoras niger from Juruá River, State of Acre, Brazil. Cosmetocleithrum undulatum and Cosmetocleithrum brachylecis resemble Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 mainly by the unique male copulatory organ (MCO) morphology but differ from these and all congeneric species mainly by the morphology of the MCO, accessory piece and hooks pairs. Cosmetocleithrum ludovicense is closer to Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986 and to Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 but differs from those mainly by the morphology of the accessory piece. Cosmetocleithrum sacciforme differs from all congeneric species mainly by the morphology of the accessory piece formed by a single plate of saccular appearance. Cosmetocleithrum basicomplexum also shares morphological characters with Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 considering the size of the body and shape of the anchors, but differs mainly in the morphology of the bars and hooks. Besides the new species, new data are presented for Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018, C. akuanduba and C. confusus regarding morphological characteristics and biogeography.

Title: Dactylogyridae (Platyhelminthes, Monogenea) des lamelles branchiales de Doradidae (Siluriformes) avec description de cinq nouvelles espèces de Cosmetocleithrum et nouvelle répartition géographique d'espèces connues de la région néotropicale au Brésil. Abstract: Cinq nouvelles espèces de Cosmetocleithrum sont décrites, parasitant les filaments branchiaux de poissons Doradidae néotropicaux. Cosmetocleithrum undulatum n. sp., Cosmetocleithrum brachylecis n. sp. et Cosmetocleithrum ludovicense n. sp. sont décrits de Platydoras brachylecis provenant d'un marché de São Luís, État du Maranhão, Brésil. Cosmetocleithrum sacciforme n. sp. et Cosmetocleithrum basicomplexum n. sp. sont décrits d'Oxydoras niger de la rivière Juruá, État d'Acre, Brésil. Cosmetocleithrum undulatum et Cosmetocleithrum brachylecis ressemblent à Cosmetocleithrum falsunilatum Feronato, Razzolini, Morey & Boeger, 2022 principalement par la morphologie unique de l'organe copulateur mâle (OCM), mais diffèrent de ces espèces et de toutes les espèces congénères principalement par la morphologie de l'OCM, de la pièce accessoire et des paires de crochets. Cosmetocleithrum ludovicense est proche de Cosmetocleithrum confusus Kritsky, Thatcher & Boeger, 1986 et de Cosmetocleithrum akuanduba Soares, Santos Neto & Domingues, 2018 mais en diffère principalement par la morphologie de la pièce accessoire. Cosmetocleithrum sacciforme se distingue de toutes les espèces congénères principalement par la morphologie de la pièce accessoire formée d'une seule plaque d'aspect sacculaire. Cosmetocleithrum basicomplexum partage également des caractères morphologiques avec Cosmetocleithrum gigas Morey, Cachique & Babilonia, 2019 compte tenu de la taille du corps et de la forme des anchors, mais en diffère principalement par la morphologie des barres et des crochets. Outre les nouvelles espèces, de nouvelles données sont présentées pour Cosmetocleithrum leandroi Soares, Neto & Domingues, 2018, C. akuanduba et C. confusus concernant les caractéristiques morphologiques et la biogéographie.

Parasite Diversity in a Freshwater Ecosystem.

Parasites are a significant component of biodiversity. They negatively affect fish appearance, growth, and reproduction. In this study, the prevalence of infection, diversity, and mean intensity of parasites were examined in 9 freshwater fish species (45 samples per fish species). Ecto-parasites were examined on the skin, gills, and fins with a hand lens. Wet mounts were prepared using mucosal scrapings from all the external and internal organs of the sampled fish. Microscopy, muscle compression, and the pepsin-HCL artificial digestion technique were also performed. In this study, 26 species of parasites were identified including three taxa belonging to 9 species of protozoan parasites, 11 treamtodes, and 6 monogenean parasites. The identified protozoan parasites were Entamoeba histolitica, Chilodonella sp., Coccidia sp., Costia sp., Cryptobia sp., Ichthyopthiris-multifilis, Microsporidia, Piscinoodinium sp., and Ichthyobodo necator. The identified trematode parasites were Fasciola gigantica, Echinostoma revolutum, Fasciola hepatica, Haplorchis pumilio, Brachylaima cribbi, Echinostoma cinetorchis, Neascus sp., Deropegus sp., Trematode Soldier, Centrocestus formosanus, and Clinostomum marginatum. The identified monogenean parasites were Dactylogyrus limipopoensis, Dactylogyrus anchoratus, Dactylogyrus myersi, Dactylogyrus vastator, Gyrodactylus salaris, and Ancyrocephalus. The diversity of parasites was maximum at the Okara site. The host's organs that were targeted for parasitic infection included the intestine, liver, gills, fins, skin, and kidneys. The majority of the parasites were identified in Labeo rohita followed by Hypophthalmichthys molitrix, Ctenopharyngodon idella, Oreochromis niloticus, Cyprinus carpio, and Wallagu attu. Two species appeared to be resistant species because none of the parasites were observed in Notopterus notopterus or Sperata seenghala. This study also concluded that the prevalence of parasites increased with increasing length, size, and age of fish.

Seasonal study of the relationship between the condition factor and the monogeneans parasite density of Heterobranchus isopterus Bleeker, 1863 and Clarias gariepinus (Burchell, 1822) fished in the Bagoué River (North-Western, Ivory Coast).

A comparative study on the relationship between condition factors and parasite density of Heterobranchus isopterus and Clarias gariepinus was conducted during the wet and dry seasons. Specimens were collected from the Bagoué River from August 2020 to July 2021. Two hundred eighty-four specimens of H. isopterus and 272 specimens of C. gariepinus were collected from all stations during both seasons. The standard length and weight of the fish were recorded and the condition factor was calculated for each individual. The gills were examined under a binocular loupe and the monogeneans were collected. Parasite counts showed that for both host species, the total number of parasites was higher in the dry season than in the wet season (p < 0.05). The correlation coefficient was determined to investigate the relationship between the condition factor and the total number of parasites. A significant positive correlation was observed between the condition factor and the number of parasites in both host species during the wet season. A negative correlation was observed in both hosts during the dry season. The information from this study could be taken into consideration in the sanitary management of the fish farming industry. The dry season could be considered as the season with favorable conditions for the development of most parasite species.

Monogeneans in intergeneric hybrids of leuciscid fish: Is parasite infection driven by hybrid heterosis, genetic incompatibilities, or host-parasite coevolutionary interactions?

BACKGROUND: Several hypotheses have been proposed to explain parasite infection in parental species and their hybrids. Hybrid heterosis is generally applied to explain the advantage for F1 generations of hybrids exhibiting a lower level of parasite infection when compared to parental species. Post-F1 generations often suffer from genetic incompatibilities potentially reflected in the higher level of parasite infection when compared to parental species. However, the presence of specific parasites in an associated host is also limited by close coevolutionary genetic host-parasite associations. This study focused on monogenean parasites closely associated with two leuciscid fish species-common bream and roach-with the aim of comparing the level of monogenean infection between parental species and hybrids representing two F1 generations with different mtDNA and two backcross generations with different cyto-nuclear compositions. RESULTS: Monogenean infection in F1 generations of hybrids was lower when compared to parental species, in line with the hybrid heterosis hypothesis. Monogenean infection in backcross generations exhibited similarities with the parental species whose genes contributed more to the backcross genotype. The distribution of monogeneans associated with one or the other parental species showed the same asymmetry with a higher proportion of roach-associated monogeneans in both F1 generations and backcross generation with roach in the paternal position. A higher proportion of common bream-associated monogeneans was found in backcross generation with common bream in the paternal position. CONCLUSIONS: Our study indicated that cyto-nuclear incompatibilities in hybrids do not induce higher monogenean infection in backcross generations when compared to parental species. However, as backcross hybrids with a higher proportion of the genes of one parental taxon also exhibited high level of this parental taxon-associated parasites, host-parasite coevolutionary interactions seem to play an obvious role in determining the level of infection of host-specific monogeneans in hybrids.

First data on parasites of the invasive brown bullhead Ameiurus nebulosus (Siluriformes: Ictaluridae) in Ukraine.

This study describes the parasite community of non-native brown bullhead, Ameiurus nebulosus (Actinopterygii: Ictaluridae), collected at three sites in the river Vistula Basin (Lake Svitiaz, Lake Pisochne, and Lake on Plastova) and one site in the river Diester Basin (Lake Stryiska), in Ukraine. Our data represent the first comprehensive study of parasite community in this fish species in Europe. Sixteen parasite taxa were found, including species co-introduced from North America and species acquired in the European range. Maximum parasite richness (13 spp.) was recorded in Lake Svitiaz situated in a Natural Protected Area, while lowest species richness (3 spp.) was observed at Lake on Plastova, an artificial pond in the city of Lviv. Three co-introduced monogenean species, Gyrodactylus nebulosus, Ligictaluridus pricei and Ligictaluridus monticellii, are recorded in Ukraine for the first time, widening the knowledge of the European distribution of these North American parasites. Metric features for hard parts of invasive and native monogeneans showed overlap in ligictalurid parasites, but slightly smaller metrics in Ukrainian G. nebulosus, possibly reflecting water temperature during fish sampling. Though prevalence and abundance of acquired parasites was relatively low, infection parameters for metacercariae of Diplostomum spp. were relatively high at Lake Svitiaz and the natural Lake Stryiska in Lviv. In two lakes in the Vistula basin, we found high prevalence and abundance of Anguillicola crassus, an Asian nematode infecting eels, possibly supporting the invasional meltdown hypothesis. Our study confirms both further spread of non-native parasites in Europe and use of non-native fish as competent hosts for local native and introduced parasites.

The survey of ectoparasites on two species of Triakids (Mustelus mustelus and M. punctulatus) sharks from Tunisian coasts.

Between 2018 and 2020, 696 fish belonging to two species of sharks from the Family Triakidae (Mustelus mustelus and M. punctulatus) were collected from the coasts of Tunisia and inspected for parasites. Six copepod taxa (Perissopus dentatus Steenstrup & Lütken, 1861, Eudactylinella alba Wilson, 1932, Kroyeria lineata Van Beneden, 1853, Nesippus orientalis Heller, 1865 and Lernaeopoda galei Krøyer, 1837, Kroyeria sp.), four isopod species (Anilocra physodes (Linnaeus, 1758), Emetha audouini (H. Milne Edwards, 1840), Ceratothoa parallela (Otto, 1828) and Ceratothoa oestroides (Risso, 1816)) and two monogenean species (Erpocotyle sp1. And Erpocotyle sp2) were collected. A large number of global host records was reported, including the occurrence of E. audouini on M. mustelus and of Erpocotyle sp.2 on M. punctulatus. The study of the diversity of parasites per host species revealed that M. mustelus had a higher parasitic richness compared to M. punctulatus . In this study, it was provided for the first records on ectoparasites on Triakidae sharks from Tunisian coasts and their infection indices.

Monogenean body size, but not reproduction, increases with infracommunity density.

Body size reveals a plethora of life-history, ecological, and evolutionary information about a species. It plays a critical role in success or failure during competitive, reproductive, or predator-prey interactions. Typically, there is a negative relationship between body size and population density in natural populations and communities. I analysed this relationship within and among multiple populations of two prominent monogenean parasites (>90% prevalence) on Lepomis macrochirus in three lakes in New Jersey (USA), using multiple regression models. To elucidate the causes and benefits of this relationship, I also measured host body condition via a regression index, and reproductive output of the parasite community by measuring parasite eggs shed from the host. The relationship between body size and density of infrapopulations (parasites of a single species on a single host) was positive, and the strength of this relationship for both species depended on which lake they occupied, indicating the potential for Allee effects. This relationship persists at the infracommunity level, where there was a similar positive relationship between a community weighted mean body size and density. However, this relationship did not result in greater reproductive success as measured by infracommunity egg production per individual per 24 h or egg size. The cause of this relationship also remains elusive; it was not explained by host condition or age. The results suggest that there is either no reproductive advantage to this increase in body size or the advantage conferred was not related to these measured fitness components. These findings indicate that researchers should be cautious using body size as a proxy for fitness or reproduction, while also raising further questions about the nature of the relationship between parasites on a host and that between those parasites and the host.

Experimental evidence that host choice by parasites is age-dependent in a fish-monogenean system.

Host age is known to influence the risk of parasite infection, but there is very little experimental evidence on whether parasites show preference towards potential hosts of a specific age. To investigate how host age affects host choice by parasites, we used the Nile tilapia (Oreochromis niloticus) as a fish parasite model and manipulated its gill ectoparasitic monogeneans in mesocosm experiments. Our experimental setting combined three age classes (juvenile, subadult, and adult) of both infected donor hosts and uninfected potential target hosts assigned to each treatment. We predicted that adult target hosts would be more susceptible to parasites than juveniles and adults because they represent high-quality habitat patches. Contrary to our prediction, we found that subadults were more susceptible to parasites than juvenile and adult target hosts. Our models confirmed that variation in target host age influenced parasite choice, suggesting that subadults might represent the most favourable option for parasites regarding a balance between host quality and susceptibility. We provide experimental evidence that host choice by parasites is age-dependent, and that this life-history trait can play a major role in structuring parasite populations.

Trichlorfon is effective against Dawestrema cycloancistrium and does not alter the physiological parameters of arapaima (Arapaima gigas): A large Neotropical fish from the Amazon.

This study investigated the in vitro and in vivo efficacy of trichlorfon against Dawestrema cycloancistrium, as well as its physiological effects on arapaima. Naturally parasitized arapaima gill arches were exposed in vitro to 100, 250, 500 and 750 mg/L of trichlorfon and a control group (only distilled water), in triplicate. Parasites were monitored, and mortality was used to determine the median effective concentration (EC50 ). The 750 mg/L concentration demonstrated 100% in vitro efficacy against D. cycloancistrium after 60 min, while the intermediate (500 mg/L) and the lowest (100 and 250 mg/L) tested concentrations were completely efficient after 90 and 130 min, respectively. The EC50-1h of trichlorfon for D. cycloancistrium was determined at 171.73 mg/L. Parasitized arapaima juveniles were exposed to a control group and 150 mg/L of trichlorfon in triplicate. Fish were exposed to two therapeutic baths for 60 min with 24-h intervals between treatments. Therapeutic baths with 150 mg/L of trichlorfon were 92.99% effective against D. cycloancistrium and did not bring about haematological alterations (erythrogram, white blood cell count, thrombogram, plasma glucose and total proteins). Therefore, 150 mg/L of trichlorfon can be used in therapeutic baths to control and treat D. cycloancistrium infestations with no physiological impairments for arapaima.

Geographic range, distribution patterns and interactions of Monogenea Van Beneden 1858, with species of native host freshwater fishes from Brazil / Distribuição geográfica, padrões de distribuição e interações de Monogenea Van Beneden 1858, com espécies de peixes hospedeiros nativos de água doce do Brasil

Abstract This paper investigated information on monogenean species using 312 scientific papers, to search for infection and geographic distribution patterns in native freshwater fish from Brazil. We used 1,698 samples of 296 fish species of 28 families distributed into Characiformes, Siluriformes, Cichliformes, Gymnotiformes, Perciformes, Mugiliformes, Osteoglossiformes and Clupeiformes, in addition to four hybrid fish. Among the hosts of the different orders and families, the greatest numbers of parasite-host associations were found for species of the families Serrasalmidae, Characidae, Loricariidae, Curimatidae and Anostomidae. The 578 species of monogeneans used in parasite-host interactions were distributed in 86 genera of six five families (Dactylogyridae, Gyrodactylidae, Diplectanidae, Microcotylidae, Ancylodiscoididae and Ancyrocephalidae), but with great predominance of Dactylogyridae species. There was variation in prevalence, intensity and abundance levels of monogeneans species among host fish species, as well as in infection sites that occurred predominantly in external organs. Positive correlations of prevalence, intensity and abundance with body length of hosts were observed. There was geographic distribution pattern of monogeneans limited mostly to two hydrographic basins those being the Amazon River and Paraná River. Just approximately 6% of potential monogeneans have been explored thus far, showing a clear need for further studies on this interesting group of parasites.

Resumo Este estudo investigou informações sobre espécies de monogenéticos, usando 312 artigos científicos para buscar padrões de infecção e distribuição geográfica em peixes nativos de água doce do Brasil. Foram utilizadas 1.698 amostras de 296 espécies de peixes de 28 famílias, distribuídas em Characiformes, Siluriformes, Cichliformes, Gymnotiformes, Perciformes, Mugiliformes, Osteoglossiformes e Clupeiformes, além de quatro peixes híbridos. Entre os hospedeiros das diferentes ordens e famílias, os maiores números de associações parasito-hospedeiro foram encontrados para espécies das famílias Serrasalmidae, Characidae, Loricariidae, Curimatidae e Anostomidae. As 578 espécies de monogenéticos, utilizadas nas interações parasito-hospedeiro, foram distribuídas em 86 gêneros de seis famílias (Dactylogyridae, Gyrodactylidae, Diplectanidae, Microcotylidae, Ancylodiscoididae e Ancyrocephalidae), mas com grande predominância de espécie de Dactylogyridae. Houve variação nos níveis de prevalência, intensidade e abundância das espécies de monogenéticos entre as espécies de peixes hospedeiros, bem como nos locais de infecção que ocorreram predominantemente em órgãos externos. Correlações positivas de prevalência, intensidade e abundância com o comprimento corporal dos hospedeiros foram observadas. Houve padrão de distribuição geográfica dos monogenéticos limitados principalmente a duas bacias hidrográficas, sendo elas o Rio Amazonas e Rio Paraná. Apenas aproximadamente 6% dos potenciais monogenéticos são conhecidos até agora, mostrando uma clara necessidade de mais estudos sobre esse interessante grupo de parasitos.

Morphological and molecular data of new species of Characithecium and Diaphorocleidus (Monogenea: Dactylogyridae) from Neotropical characid fishes.

The present study describes three new species of monogenean parasites of characid fishes from the Upper Paraná River basin, Brazil: Characithecium paranapanemense n. sp. on Psalidodon paranae and Psalidodon bockmanni, Diaphorocleidus magnus n. sp. on Astyanax lacustris and Psalidodon fasciatus, and Diaphorocleidus neotropicalis n. sp. on Astyanax lacustris and P. bockmanni. An amendment for Diaphorocleidus is proposed, since additional characters observed in the new species required to extend the generic diagnostic features mainly to include: articulation process connecting the base of the MCO with accessory piece present or absent, and accessory piece with variable shapes (plate-like, pincer-shaped, wrench-shaped, sheath-shaped), divided or not into subunits. Characithecium paranapanemense n. sp. can be distinguished from other congeners by the morphology of its MCO and accessory piece. Diaphorocleidus magnus n. sp. differs from most of its congeners by the morphology of its accessory piece, the presence of articulation process connecting the base of the MCO with accessory piece, and the morphology of the sclerotized structures of the haptor. Diaphorocleidus neotropicalis n. sp. can be easily distinguished from its congeners by the morphology of the accessory piece, the sclerotized structures of the haptor and the morphology of the vagina. Molecular data of the new species (partial 28S rDNA and mitochondrial cytochrome oxidase I) were obtained and the first phylogenetic analysis based on 28S rDNA gene sequences for species of Characithecium and Diaphorocleidus are provided. Although Diaphorocleidus and Characithecium share some morphological similarities, phylogenetic analysis indicates that species of these two genera are not closely related.

Metal accumulation in ecto- and endoparasites from the anadromous fish, the Pontic shad (Alosa immaculata).

Among the parasitic taxa studied for their metal accumulation properties, especially Acanthocephala and Cestoda proved to be promising sentinels for metal pollution. However, studies on metal accumulation are still sparse for other parasite groups, mainly due to their small body size. In the present study, we collected the relatively large-sized monogenean Mazocraes alosae Hermann, 1782 from the gills of Pontic Shad (Alosa immaculata Bennet 1835) from its spawning region ­ the Danube River. The host tissues gills, muscle, intestine and liver, the monogeneans as well as the nematode Hysterothylacium aduncum (Rudolphi, 1802), in the cases of coinfected fish, were analysed for the elements As, Cd, Co, Cu, Fe, Mn, Pb, Se and Zn. All elements (except of As) were found in higher concentrations in monogeneans and nematodes compared to host muscle tissue. High bioconcentration factors were obtained for toxic elements such as Cd and Pb with concentrations being approximately 12 and 251 times higher in monogeneans and 773 and 33 in nematodes, respectively, as compared to host muscle tissue. In comparison to other host organs, however, some elements were found in similar or even lower concentrations in the parasites. Thus, monogeneans do not exhibit the high accumulation potential reported for other parasitic taxa. Physiological adaptations of the migratory host fish between freshwater and marine habitats with differences in uptake pathways and biological availability of elements can be discussed as a possible explanation for this divergent accumulation pattern.

A New Species of Mymarothecium tantaliani n. sp (Monogenea: Dactylogiridae) in the Gills of Gamitana Colossoma macropomum (Cuvier) from Madre de Dios, Peru.

INTRODUCTION: Members of the genus Mymarothecium Kritsky, Boeger & Jégu, 1996 infect characiform fish in the Amazon River Basin. Although the Peruvian Amazon hosts rich fauna of fish, the taxonomic diversity of parasitic organisms such as Mymarothecium has been few explored. A new species of Mymarothecium in Colossoma macropomum Cuvier, from the southeast of the Peruvian Amazon, is described. METHODS: Monogeneans were isolated from gills of C. macropomum, fixed in formaldehyde in 4% solution. For morphological examinations were stained with Gomori's trichrome and others were clarified with Hoyer's medium. RESULTS: Mymarothecium is the third species of the genus recorded in C. macropomum. These new species have been characterized by a slightly sigmoid male copulatory organ (MCO) and the accessory piece with sinuous distal rod with hook-shaped process and a bifurcation in the middle part. Furthermore, the anteromedial projection of the ventral rod has a small conspicuous filament in both anchors. CONCLUSIONS: With the description of this new species, eight species of Mymarothecium have been reported in fish of the Serrasalmidae family originating in the Amazon.

Data from monogenean and endohelminth communities in twospot livebearer Pseudoxiphophorus bimaculatus (Teleostei: Poeciliidae) populations in a neotropical river.

The data presented in this article are related to the research article entitled "Competition from sea to mountain: interactions and aggregation in low diversity monogenean and endohelminth communities in twospot livebearer Pseudoxiphophorus bimaculatus (Teleostei: Poeciliidae) populations in a neotropical river." accepted for publication in Ecology and Evolution. The data describes the communities of helminth parasites in 11 populations of a small poeciliid freshwater fish Pseudoxiphophorus bimaculatus (Heckel, 1848) sampled along the La Antigua river basin in Veracruz, Mexico. We examined 19 P bimaculatus from one locality, 21 from another locality, and 20 from each of the other nine locations sampled in June 2016. A total of 220 individual fish were examined, and in this paper we provide the data for 18 helminth parasite taxa recorded from them. The material in this Data paper comprised the raw data on the abundance, i.e. the number of helminth individuals of each of 18 taxa found in each one individual of P. bimaculatus from each of 11 localities. The data set is contained in a single text-table including one matrix containing each of the 220 host P. bimaculatus examined from 11 localities (lines). Measures for each host P. bimaculatus include total length, standard length, maximum deep and sex, documented for everyone fish examined, plus data of the number of individual helminth of each taxa collected by each examined fish are placed in the columns. These data might be used to examine spatial distribution of helminth parasite taxa. These data might be reused to examine the spatial variation in community structure of helminth parasites of freshwater fish. This kind of data could be used to provide an assessment of human environmental impacts, or for public awareness of conservation objectives.

Diversity of helminth parasites of freshwater fish in the headwaters of the Coatzacoalcos River, in Oaxaca, Mexico.

We documented the diversity of helminth parasites of 25 fish species from 8 families occurring in the headwaters of the Coatzacoalcos river basin. This river flows along the border between the states of Oaxaca and Veracruz, in the region of the Isthmus of Tehuantepec, in south-eastern Mexico, and in northern Central America. We recorded 48 species, representing 44 genera and 29 helminth families. Six of the 25 fish species were examined for helminths for the first time; 60 new host records were reported. Nematodes and trematodes were the most abundant taxonomic groups. The helminth fauna from our study area consists of primarily central American species. Most species recorded from this area have also been captured from freshwater bodies between the Isthmus of Tehuantepec and the Isthmus of Panama. However, three species, including an acanthocephalan and two nematodes, are likely endemic to this area. We argue that, in contrast to the presence of larval helminths, which mostly depends on the geographical location of water bodies, adult helminths are an integral and consistent component of the regional community. Data on taxonomic composition and distribution of helminth fauna reported in this paper, contribute to a better understanding of this faunal component in northern Central America (CA). Furthermore, knowledge of helminth parasites of freshwater fish from Neotropical Mexico and CA facilitates prediction of which parasite species is likely to infect fish in a specific geographical area.

Dactylogyrus spp. (Monogenea, Dactylogyridae) from the Gills of Enteromius spp. (Cypriniformes, Cyprinidae) from the Limpopo Province, South Africa with Descriptions of Three New Species.

BACKGROUND: Monogenean parasites of the genus Dactylogyrus Diesing, 1850 parasitize mostly gills of cyprinoids hosts. Of 100 species currently known from African continent, approximately 35 have been described from Enteromius spp. Results of recent studies indicate that there are still many undescribed species of the genus Dactylogyrus in South Africa and systematic surveys can bring many new findings. METHODS: During the period April 2015-May 2016, three species of the genus Enteromius were sampled from eight localities across Limpopo Province. Monogenean parasites were collected from the gills of the hosts using stereomicroscopes. Morphometric analysis of the hard parts of the attachment organ and male copulatory organs were performed to confirm species identity. RESULTS: Presence of three new and three previously described Dactylogyrus species is reported. Newly described species include: Dactylogyrus afrohamiltoni sp. nov. from Enteromius afrohamiltoni; Dactylogyrus limpopoensis sp. nov. and Dactylogyrus letabaensis sp. nov. from Enteromius unitaeniatus. In addition, Dactylogyrus afrolongicornis, Dactylogyrus allolongionchus and Dactylogyrus myersi were identified from Enteromius trimaculatus. Newly identified species possess morphometric characters based on which they can be clearly identified from currently known species. CONCLUSION: Present results show that small barbs, especially those not previously studied for monogenean parasites, are potentially very interesting target to study to recover new species of the genus Dactylogyrus and to bring new contribution to the knowledge of the diversity of African parasites.

You are how you eat: differences in trophic position of two parasite species infecting a single host according to stable isotopes.

Parasitism is commonly recognised as a consumer strategy, although, the interaction of parasites in communities and ecosystems are generally poorly understood. As parasites are integral parts of food webs, analysis of the trophic interactions between parasites and hosts was assessed through comparison of stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N). Largemouth yellowfish (Labeobarbus kimberleyensis) infected with the Asian tapeworm (Schyzocotyle acheilognathi) were collected from the Vaal Dam. Signatures of δ13C and δ15N were assessed in host muscle and liver tissue, and cestodes using an elemental analyser coupled with an isotope ratio-mass spectrometer (EA-IRMS). Hosts were enriched by 4.1‰ in the heavy nitrogen isotope with respect to the S. acheilognathi and therefore occupy a higher trophic position than the parasite. Comparison of δ13C indicates that dietary sources of carbon in cestodes are derived from the host liver. Comparison of stable isotope signatures between Paradiplozoon ichthyoxanthon (another common parasite of the Largemouth yellowfish in the Vaal River) and S. acheilognathi showed that the monogenean was enriched by 5.3‰ in 15N which accounts for a difference of almost two trophic positions. Isotope differences in the host-parasite system considered indicate that differences can be related to the mode of nutrient acquisition employed by host and parasites. Cestodes, being depleted in both 13C and 15N relative to the host and monogenean (P. ichthyoxanthon), indicate that S. acheilognathi assimilates nutrients derived from the host metabolism which are released from the liver.

Redescription and First Nucleotide Sequences of Rhinobatonchocotyle pacifica Oliva & Luque, 1995 (Monogenea: Hexabothriidae), a Parasite of Pseudobatos planiceps (Garman, 1880) (Rhinopristiformes: Rhinobatidae) from Peru.

INTRODUCTION: Specimens of Rhinobatonchocotyle pacifica Oliva & Luque, 1995 (Hexabothriidae) were collected from the gill filaments of Pacific guitarfish, Pseudobatos planiceps (Garman, 1880) (Rhinopristiformes: Rhinobatidae), from off the coast of Chorrillos, Lima, Peru. Since the original description of R. pacifica was incomplete, we herein redescribe R. pacifica based on re-examination of the holotype, paratypes, and newly collected voucher specimens. Nucleotide sequences (18S, 28S) for R. pacifica are presented for the first time, and a phylogenetic analysis conducted. MATERIALS AND METHODS: Monogeneans were examined with light microscopy and partial sequences of 18S and 28S rDNA genes were obtained. RESULTS: The following taxonomically important morphological features are described: presence of seminal receptacle, spiniform papillae within oral cavity, haptoral sucker sclerites and anchors, hook surface striations, muscular pad associated with each haptoral sucker sclerite (except sclerite 1), muscular bulbs in appendix suckers, and oötype lacking longitudinal rows of large cells (oötype not côtelé). The genital complex is detailed. The diagnosis of Rhinobatonchocotyle is emended to include species with or without seminal receptacle. Representative nucleotide sequences of partial 18S and 28S rDNA genes of R. pacifica were obtained for the first time and used for reconstructing the phylogeny of Hexabothriidae. CONCLUSION: The phylogenetic reconstruction confirmed the species within the Hexabothriidae.