Morphological and molecular data on Phyllodistomum (Digenea: Gorgoderidae) from Brazil, with the description of a new species parasitizing Hoplias malabaricus (Bloch, 1794) (Osteichthyes, Erythrinidae).

Phyllodistomum pepirense n. sp. is described from the urinary bladder of Hoplias malabaricus (Bloch, 1794), sampled in the Jacaré-Pepira River in São Paulo state, Brazil. The isolates of the new species were recovered as a monophyletic group in the phylogenetic analysis of the 28S rRNA gene, which showed the new species as the sister taxa of Phyllodistomum virmantasi Pinacho-Pinacho, Sereno-Uribe, Hernández-Orts, García-Varela & Pérez-Ponce de León, 2021, a species sampled from an eleotrid fish in Southeastern Mexico. The new species differs morphologically from P. virmantasi by having a larger body size, slightly lobed testes and ovary, a mostly intercaecal uterus, slightly diverticulated caeca, and vitelline masses irregularly shaped. The new species is also readily distinguished from other species of Phyllodistomum Braun, 1899 reported from freshwater fishes in Brazil - namely, P. rhamdiae Amato & Amato, 1993 and P. spatula Odhner, 1902. The new species is herein described based on morphological characteristics, molecular data from D1-D3 domains of the 28S rRNA gene, host association, and geographical distribution.

A new species of Creptotrematina (Trematoda: Allocreadiidae) from characid fishes of Brazil: morphological and molecular data.

A new species of Creptotrematina Yamaguti, 1954 was collected from characid fishes, Astyanax fasciatus (Cuvier, 1819) and Astyanax lacustris Lucerna & Soares, 2016 from the Batalha River in the State of Sao Paulo, Brazil. The new species most closely resembles Creptotrematina aguirrepequenoi, but differs by the elongated shape of vitelline follicles, the extension of these follicles in the posterior end of body and the fact that they are not confluent. The morphological differences were confirmed through molecular data. Three specimens were sequenced, and molecular analyses were based on the internal transcribed spacers 2 and D1-D3 domains of the 28S ribosomal RNA gene. The obtained topologies showed the new species as a sister taxon of C. aguirrepequenoi, a species originally described from Astyanax mexicanus in Mexico, and later found in Astyanax aeneus in Costa Rica. Isolates of the new species are reciprocally monophyletic, and genetic distance values are similar to those observed in other species pairs within Allocreadiidae. These findings corroborate that the genus Creptotrematina is mostly a parasite of characids, and widely extended across the Americas, with representative species occurring between Argentina and northern Mexico.

Seasonal patterns of infestation by monogenean parasites of fish and their relationship with water parameters in two rivers with different disturbance gradients in southeastern Brazil.

Here, we evaluate the relationships between the infestation rates of five monogenean parasites species with the dry and wet seasons, with the organic and inorganic parameters of the water of two rivers: the Jacaré-Pepira and Jacaré-Guaçú, and with the condition factors of its fish hosts: Serrasalmus maculatus and Astronotus crassipinnis, in the state of São Paulo, southeastern Brazil. Fish were collected between January and December 2017. Anacanthorus serrasalmi, Amphithecium speirocamarotum and Gussevia asota had higher abundance rates (Student's t test, p ≤ 0.05) in the wet season. Gussevia asota had its abundance negatively correlated to nitrate in the Jacaré-Pepira River and with total nitrogen and potassium in the Jacaré-Guaçú River. Regarding the fish hosts condition factors, was observed a positive correlation with the abundances of G. asota in the Jacaré-Guaçú River, and with A. serrasalmi in the Jacaré-Pepira River. In general, wet season favored an increasing in the infestation rates of the monogeneans parasites in their host species, mainly in the river considered as the most polluted, the Jacaré-Guaçú River. Of the five parasites species analyzed in this study, only Gussevia astronoti and Rhinoxenus piranhus had no interaction with seasonality, river water variables, or fish host condition factors. On the other hand, G. asota had interactions both with water parameters (nitrate and total nitrogen) and with the hosts condition factors, which reflected in the abundance and intensity rates, showing itself as a species sensitive to changes in the environment and, therefore, that can be considered as a bioindicator organism.

Metazoan parasites of the lambari Astyanax altiparanae collected in the Batalha River, State of São Paulo, Brazil.

Here we conduct a qualitative and quantitative analysis of ectoparasites and endoparasites of Astyanax altiparanae (Garutti & Britski, 2000), popularly known as lambari-do-rabo-amarelo collected from the Batalha River, State of São Paulo, Brazil. Of the 67 specimens of A. altiparanae, 52 were parasitized by at least one parasitic metazoan species. The following metazoan parasites were found: Monogenea, Digenea and Nematoda. The monogenetic Diaphorocleidus sp. was the predominant species, presenting a higher frequency of dominance, prevalence and mean abundance. However, the monogenean Trinigyrus sp. was the one with the highest mean intensity value. All parasites showed aggregate distribution pattern. The parasitic community of A. altiparanae was characterized by low diversity, low richness and low uniformity. The digenetic Rhipidocotyle santanaensis is recorded for the first time in A. altiparanae, in the same way, this parasite is being registered for the first time in the Batalha River.

First record of Rhipidocotyle santanaensis (Digenea) parasitizing Acestrorhynchus lacustris from Batalha River, Brazil.

This paper describes the occurrence of digenetic Rhipidocotyle santanaensis Lunaschi, 2004 in Brazil. This parasite was found in the liver, heart, gonads, intestine, pyloric caeca, stomach, swim bladder and cavity of Acestrorhynchus lacustris (Lütken, 1875) from the Batalha River, São Paulo State, with higher incidence in gonads and digestive tract. The parasite specimens found in this study showed morphological characteristics very similar to specimens from Argentina, with differences only in relation to the ejaculatory duct and seminal vesicle. However, Brazilian specimens presented great morphometrical differences between specimens described in Argentina, with much higher measures. This is the first record of this metazoan parasite species in Brazil and in this host fish.

First record of Palombitrema triangulum (Suriano, 1981) Suriano, 1997 (Monogenea: Dactylogyridae) from freshwater fishes in Brazil.

This study reports for the first time the monogenean Palombitrema triangulum Suriano (1981) in freshwater fishes from Brazil, highlighting new sites of infection for this helminth and some morphological differences. Monogeneans were collected on the body surface, gills and nasal cavity of two native fish species from Brazil, Cyphocharax modestus (Fernández-Yépez, 1948) and Cyphocharax nagelii (Steindachner, 1881). A brief morphological characterization of this species is presented.

First record of an epibiont protozoan Epistylis sp. (Ciliophora, Peritrichia) attached to Ergasilus chelangulatus (Ergasilidae) in Brazil.

In the present paper, we described the first record of an epibiont protozoan Epistylis sp. Ehrenberg, 1830 (Ciliophora, Peritrichia) attached to Ergasilus chelangulatus Thatcher and Brasil-Sato, 2008, parasite of Pimelodus maculatus Lacépède, 1803 in Brazil, with electron microscope observations. Fish were collected in Veados River, state of São Paulo and the crustacean Ergasilus chelangulatus being registered for the first time in this river, expanding its geographical distribution in Brazil.

Metazoan parasites of the lambari Astyanax altiparanae collected in the Batalha River, State of São Paulo, Brazil / Metazoários parasitos do lambari Astyanax altiparanae coletados no rio Batalha, estado de São Paulo, Brasil

Abstract Here we conduct a qualitative and quantitative analysis of ectoparasites and endoparasites of Astyanax altiparanae (Garutti & Britski, 2000), popularly known as lambari-do-rabo-amarelo collected from the Batalha River, State of São Paulo, Brazil. Of the 67 specimens of A. altiparanae, 52 were parasitized by at least one parasitic metazoan species. The following metazoan parasites were found: Monogenea, Digenea and Nematoda. The monogenetic Diaphorocleidus sp. was the predominant species, presenting a higher frequency of dominance, prevalence and mean abundance. However, the monogenean Trinigyrus sp. was the one with the highest mean intensity value. All parasites showed aggregate distribution pattern. The parasitic community of A. altiparanae was characterized by low diversity, low richness and low uniformity. The digenetic Rhipidocotyle santanaensis is recorded for the first time in A. altiparanae, in the same way, this parasite is being registered for the first time in the Batalha River.

Resumo Foi realizada uma análise qualitativa e quantitativa de ectoparasitas e endoparasitas de Astyanax altiparanae (Garutti & Britski, 2000), popularmente conhecido como lambari-do-rabo-amarelo coletados no rio Batalha, estado de São Paulo, Brasil. Dos 67 espécimes de A. altiparanae, 52 estavam parasitados por pelo menos uma espécie de metazoário parasito. Foram encontrados os seguintes metazoários parasitos: Monogenea, Digenea e Nematoda. O monogenético Diaphorocleidus sp. foi a espécie predominante, apresentando maior frequência de dominância, prevalência e abundância média. Porém o monogenético Trinigyrus sp. foi o que apresentou maior valor de intensidade média. Todos os parasitos mostraram padrão de distribuição agregado. A comunidade parasitária de A. altiparanae foi caracterizada pela baixa diversidade, baixa riqueza e baixa uniformidade. Registra-se pela primeira vez o digenético Rhipidocotyle santanaensis em A. altiparanae, da mesma forma, este parasito está sendo registrado pela primeira vez no rio Batalha.

Ectoparasites as numerical dominant species in parasite community of Trachelyopterus striatulus (Siluriformes: Auchenipteridae) from Guandu River, southeastern Brazil.

Sixty specimens of singing catfish Trachelyopterus striatulus (Steindachner, 1877) (Siluriformes: Auchenipteridae) collected from Guandu River (22º 48' 32" S and 43º 37' 35" W), in the state of Rio de Janeiro, Brazil from October 2006 to March 2009, were necropsied to study their parasites. From the 60 specimens of T. striatulus examined 57 were parasitised by at least one parasite species. The majority of the parasite specimens collected were monogeneans followed by Nematoda, Digenea and Hirudinea. Cosmetocleithrum sp. was the numerically predominant species with highest prevalence and abundance. The parasites of T. striatulus showed the typical pattern of aggregated distribution. No parasite species showed significant correlation between the body total length of the host and their abundance. The mean parasite species richness was not correlated with the host's total body length and sex. Values of the Brillouin index of diversity had a mean of H = 0.083 ± 0.136.

First record of Rhipidocotyle santanaensis (Digenea) parasitizing Acestrorhynchus lacustris from Batalha River, Brazil / Primeiro registro de Rhipidocotyle santanaensis (Digenea) parasitando Acestrorhynchus lacustris do rio Batalha, Brasil

Abstract This paper describes the occurrence of digenetic Rhipidocotyle santanaensis Lunaschi, 2004 in Brazil. This parasite was found in the liver, heart, gonads, intestine, pyloric caeca, stomach, swim bladder and cavity of Acestrorhynchus lacustris (Lütken, 1875) from the Batalha River, São Paulo State, with higher incidence in gonads and digestive tract. The parasite specimens found in this study showed morphological characteristics very similar to specimens from Argentina, with differences only in relation to the ejaculatory duct and seminal vesicle. However, Brazilian specimens presented great morphometrical differences between specimens described in Argentina, with much higher measures. This is the first record of this metazoan parasite species in Brazil and in this host fish.

Resumo O presente trabalho descreve a ocorrência do digenético Rhipidocotyle santanaensis Lunaschi, 2004 no Brasil. Estes parasitos foram encontrados no fígado, coração, gônadas, intestino, cecos pilóricos, estômago, bexiga natatória e cavidade do peixe Acestrorhynchus lacustris (Lütken, 1875) provenientes do rio Batalha, Estado de São Paulo, com maior abundância nas gônadas e trato digestório. Os espécimes dos parasitos encontrados neste trabalho apresentaram características morfológicas muito semelhantes aos espécimes provenientes da Argentina, com diferenças apenas em relação ao ducto ejaculatório e vesícula seminal. Porém, os exemplares brasileiros apresentaram grandes diferenças morfométricas entre os espécimes descritos na Argentina, com medidas muito superiores. Este é o primeiro registro desta espécie de parasito no Brasil e neste hospedeiro.

Expanded description of Dolops bidentata (Bouvier, 1899) (Branchiura: Argulidae) based on specimens collected on Pygocentrus nattereri Kner, 1858 (Characiformes) from Poconé Wetland, MT, Brazil.

The current information on the branchiuran Dolops bidentata, a species described more one hundred years ago, is valid but incomplete; hence, an expanded description is given herein. Additional morphological information was obtained by light and scanning electron microscopy from specimens collected on Pygocentrus nattereri from the Poconé Wetland, MT, Brazil. Description of the appendages and other structures such as respiratory area, mouth, details and ornamentation of antennules and maxillae are provided for the first time.