RESUMO

Although some parasitological efforts have focused on the frigate tuna Auxis thazard (Lacepède) (Scombriformes, Scombridae) in Brazil, its digenean fauna remains poorly known. Combining morphological and molecular methods, we investigated the diversity of digenean trematodes of A. thazard collected from the coastal waters off the state of Rio de Janeiro, Brazil in 2021. Six species belonging to four families were recorded: the bucephalid Rhipidocotyle cf. angusticolle Chandler, 1941, the didymozoid Didymocystis sp. 6 sensu Louvard et al. (2022), the fellodistomid Tergestia sp., and three hemiurids, Dinurus euthynni Yamaguti, 1934, Lecithochirium floridense (Manter, 1934), and L. synodi Manter, 1931. The current study brings the total number of digenean trematode species parasitising A. thazard in Brazil up to eight, with hemiuroid trematodes being most diverse. Auxis thazard is a new host record for L. floridense, L. synodi and potentially for R. angusticolle. The geographic distribution of several species found in our study appeared to be wider than previously known. Our study is the first to apply a DNA-based approach to digenean diversity in marine fishes in Brazil and we believe that both morphological descriptions and molecular sequence data provided in our study will aid future research assessing the diversity of digenean trematodes of A. thazard and other marine fishes in Brazil.

Title: Trématodes Digènes infectant l'auxide Auxis thazard (Scombriformes, Scombridae) au large de la côte de Rio de Janeiro, Brésil, avec des données moléculaires. Abstract: Bien que certains efforts parasitologiques aient porté sur l'auxide Auxis thazard (Lacepède) (Scombriformes : Scombridae) au Brésil, la faune de ses digènes reste mal connue. En combinant des méthodes morphologiques et moléculaires, nous avons étudié la diversité des trématodes digènes d'A. thazard collectés dans les eaux côtières au large de l'État de Rio de Janeiro, Brésil en 2021. Six espèces appartenant à quatre familles ont été répertoriées : le Bucephalidae Rhipidocotyle cf. angusticolle Chandler, 1941, le Didymozoidae Didymocystis sp. 6 sensu Louvard et al. (2022), le Fellodistomidae Tergestia sp., et trois Hemiuridae, Dinurus euthynni Yamaguti, 1934, Lecithochirium floridense (Manter, 1934) et L. synodi Manter, 1931. L'étude actuelle porte le nombre total d'espèces de trématodes digènes parasitant A. thazard au Brésil à huit, les Hemiuroidea étant les plus diversifiés. Auxis thazard est un nouveau signalement d'hôte pour L. floridense, L. synodi et potentiellement R. angusticolle. La répartition géographique de plusieurs espèces trouvées dans notre étude semble être plus large que ce que nous savions auparavant. Notre étude est la première à appliquer une approche basée sur l'ADN à la diversité des digènes chez les poissons marins au Brésil et nous pensons que les descriptions morphologiques et les données de séquence moléculaire fournies dans notre étude aideront les recherches futures évaluant la diversité des trématodes digènes d'A. thazard et d'autres poissons marins du Brésil.

Assuntos

RESUMO

A survey of pathological conditions affecting the natural beds of the dominant bivalve species of the intertidal rocky coasts of the Southern Atlantic Ocean, was performed. Samples of the little mussel (n = 992), Brachidontes rodriguezii, which is considered a sentinel species, were collected from seven sites that present different anthropogenic activity (low anthropogenic activity, harbor, and sewage waste) along the Argentinean coast, and processed by standard histological techniques. Our results showed for the first time in a B. rodriguezii population from Mar del Plata harbor a bacterium causing cellular lysis of the spermatogenic cells (6.5% of prevalence) and in a population from Villa Gesell, a site with low anthropogenic activity, one little mussel presented cytoplasmic vacuoles in the oocytes's cytoplasm similar to a microsporidian (0.2% of prevalence). A ciliated protozoan parasitizing the cytoplasm of the epithelial digestive tubules and larval stages of two different digenean parasites, was found infecting the little mussel from both contaminated and uncontaminated sites. Sporocysts of the family Bucephalidae invaded the gonad, causing severe gonadal damage including castration, and gymnophallid metacercariae located between the mantle and shell or embedded in the mantle tissues, occupied the gonadal space. In Punta Carballido, a site located next to a sewage outfall, the highest prevalence of infection was found, for the ciliated protozoan in the digestive tubules (5.1%) and for the digenean parasites (bucephalid sporocyst 24.4%, and gymnophallid metacercariae 50%). Moreover, we found a positive correlation between shell length and overall prevalence of parasites.

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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.

Assuntos

RESUMO

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.(AU)

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.(AU)

Assuntos