Two novel species of Myxobolus parasitizing the gills of Semaprochilodus insignis in the Brazilian Amazon.

The present study describes two new Myxobolus species infecting the gills of Semaprochilodus insignis, the most consumed freshwater fish species in the Brazilian Amazon. The fish specimens were caught in the Tapajós River, in the state of Pará, and the morphological, ultrastructural, small subunit ribosomal DNA (ssrDNA), and phylogenetic data of the myxosporean species were obtained. Two species of Myxobolus were found in the gills of S. insignis. Myxobolus maiai n. sp. developed in the gill filaments, and mature myxospores were round-shaped from the frontal view, measuring 12.5-14.8 (13.9 ± 0.5) µm in length, 11.4-13.8 (12.3 ± 0.5) µm in width, and have a thickness of 6.4-7.7 (6.9 ± 0.6) µm in the lateral view, with symmetric values. Its polar capsules were 4.4-6.6 (5.5 ± 0.5) µm in length and 2.3-3.7 (3.0 ± 0.3) µm in width, and the polar tubules had 4 - 5 coils. Myxobolus iarakiensis n. sp. was found infecting the gill arch. Mature myxospores were oval-shaped from the frontal view, and measured 6.7-8.6 (8.0 ± 0.4) µm in length, 4.5-6.3 (5.6 ± 0.4) µm in width, and had a thickness of 2.7-4.7 (3.8 ± 0.5) µm in the lateral view, with symmetric values. Its polar capsules were 2.1-3.7 (2.9 ± 0.3) µm in length and 1.1-2.0 (1.5 ± 0.2) µm in width, and its polar tubules had 4 - 5 coils. The ssrDNA based phylogeny showed these two novel species as grouping in a clade composed of parasite species of Prochilodontidae hosts.

Integrative taxonomy of a new species of Therodamas (Ergasilidae) infecting the Amazonian freshwater fish Leporinus fasciatus (Anostomidae).

Crustaceans of the subclass Copepoda are an important component of the invertebrate aquatic fauna. They occur in all aquatic environments and include some representatives that are free-living organisms and others that have a parasitic lifestyle. The genus Therodamas comprises marine and freshwater copepods whose females are parasites of fish in their adult phase, with only seven species described so far. During a field survey of fish parasites in the Jari River, a large tributary of the Amazon River system, in Brazil, we found a new species of the genus Therodamas infecting Leporinus fasciatus. Therodamas longicollum n. sp. is the second strictly freshwater species known. Phylogenetic analysis showed that the new species is grouped in the family Ergasilidae, and divergence estimates showed that T. longicollum n. sp. diverged from its ancestor at around 66.34 Ma, in the late Upper Cretaceous. Therodamas longicollum n. sp. differs from its congeneric in that it does not have lobes and/or expansion of the anterior neck region. Besides describing a new Therodamas species, thereby increasing the diversity of the genus to eight species, this study points out the existence of a lineage of these copepods that has adapted to the freshwater environment of the Amazon. This study also corroborates the genus Therodamas as part of the family Ergasilidae.

First record of Trypanosoma sp. (Kinetoplastea: Trypanosomatidae) parasiting Rhinella major in the Brazilian Amazon.

Rhinella major is one of the component species of the Rhinella granulosa group and is distributed in the neotropical region of the South American continent, being found in anthropized environments. The occurrence of trypanosomes in anurans involves a yet unknown diversity of species and hosts. In the present study, we aimed to describe the first record of Trypanosoma sp. at R. major as a new host. Of the species captured, four were positive for trypomastigote forms of Trypanosoma sp. The morphometry of the trypomastigote forms revealed parasitemia by only one morphotype. There is a need for reports and studies of parasite-host relationships in anurans and a lack of records regarding hemoparasite diversity linked to the Rhinella granulosa group.

Broad but restricted detection of malacosporeans in a Neotropical cradle of diversification.

This study undertook the first investigation of malacosporean infections in Neotropical fish. We used polymerase chain reaction detection with a primer set generally targeting known malacosporeans to assay for infection in the kidney of 146 fish in 21 species belonging to 12 families collected from two areas in the Amazon Basin. Infections were found in 13 fish variously belonging to seven species in six families and included the first identification of a malacosporean infection in cartilaginous fish (a freshwater stingray). Based on ssrDNA, all infections represented a single Buddenbrockia species (Buddenbrockia sp. E) that demonstrates an exceptionally broad range of fish species infected, and countered our expectations of high Neotropical malacosporean diversity. Infections were characterized at varying and often high prevalences in fish species but sample sizes were small. Ascertaining whether highly divergent malacosporeans have not been detected by current primers, and more comprehensive sampling may reveal whether malacosporeans are truly as species poor in the Amazon Basin as present data suggest. Our results prompt speculations about evolutionary scenarios including introduction via marine incursions and patterns of host use over time.

Morphometric Characterization of Trypanosoma spp. and blood parameters in Pterygoplichthys pardalis (Pisces: Loricariidae) from the Brazilian Amazon.

The present study describes Trypanosoma spp. infection and blood parameters in Pterygoplichthys pardalis from the Tapajós River basin in eastern Amazon (Brazil). Of 32 fish examined, 40.6% were infected by Trypanosoma spp., while a total of 112 trypomastigotes were found. Two Trypanosoma morphotypes were characterized and compared with species described in literature infecting other Loricariidae, and a similarity of 94% was found with one species described for another host. The plasma glucose and aspartate aminotransferase levels, hematocrit, number of total erythrocytes, mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) in the infected and uninfected fish were similar, but hemoglobin was lower in fish infected with Trypanosoma spp. Hemoglobin levels declined with the abundance of the hemoparasites, but the condition factor was similar among fish infected and uninfected by Trypanosoma spp. This is the first study on the hemoparasitism by Trypanosoma spp. and blood parameters in P. pardalis.

Morphology and molecular data of two novel cnidarian myxosporean (Myxobolidae) infecting Piaractus brachypomus from the Amazon basin.

The objective of this study was reports, through morphological and small subunit ribosomal DNA (SSU rDNA) sequencing, two novel myxobolid myxosporeans infecting Piaractus brachypomus, an economicaly important Amazonian fish popularly known as "pirapitinga". Of a total of 25 specimens of P. brachypomus examined 68% had the gill filament parasitized by Henneguya tapariensis n. sp. and 16% had infection of Myxobolus arapiuns n. sp. in the pyloric cecum. The morphological analysis revealed H. tapariensis n. sp. myxospores with an ellipsoid shape and caudal process larger than the length of the body. The polar capsules of same size were elongated and occupied less than half the body. Sequencing of the SSU rDNA generated a partial sequence of 1946 bp. In M. arapiuns n. sp. the myxospores had oval-shaped body and polar capsules of the same size, occupying less than half the body. Sequencing of the SSU rDNA generated a partial sequence of 1950 bp. Phylogenetic analysis revealed a cluster according to the order/family of the host, where H. tapariensis n. sp. was grouped in a subclade with Henneguya brachypomus and Henneguya piaractus and M. arapiuns grouped in a subclade with Myxobolus colossomatis, Myxobolus matosi and Myxobolus pirapitingae.

Novel Myxobolus and Ellipsomyxa species (Cnidaria: Myxozoa) parasiting Brachyplatystoma rousseauxii (Siluriformes: Pimelodidae) in the Amazon basin, Brazil.

We describe two novel myxosporean parasites from Brachyplatystoma rousseauxii, an economically important freshwater catfish from the Amazon basin, Brazil. Myxobolus tapajosi n. sp., was found in the gill filaments of 23.5% of 17 fish, with myxospores round to oval in frontal view and biconvex in lateral view: length 15 (13.5-17) µm and width 10.7 (9.6-11.4) µm; polar capsules equal, length 5.8 (4.6-7.1) µm and width 3 (2.3-3.8) µm containing polar tubules with 6-7 turns. Ellipsomyxa amazonensis n. sp. myxospores were found floating freely or inside plasmodia in the gall bladder of 23.5% of fish. The myxospores were ellipsoidal with rounded extremities: length 12.8 (12.3-13.6) µm and width 7.6 (6.7-8.7) µm; with two equal, slightly pyriform polar capsules, length 3.8 (3.8-4.0) µm and width 3.1 (2.5-3.4) µm, containing polar tubules with 2-3 turns. We combined spore morphometry, small-subunit ribosomal DNA data, specific host, and phylogenetic analyses, to identify both of these parasites as new myxozoan species. Maximum likelihood and Bayesian analyses showed that Myxobolus tapajosi n. sp. clustered in a basal branch in a subclade of parasites from exclusively South American pimelodid fishes. Ellipsomyxa amazonensis n. sp. clustered within the marine Ellipsomyxa lineage, but we suspect that although the parasite was collected in freshwater, its hosts perform a large migration throughout the Amazon basin and may have become infected from a brackish/marine polychaete host during the estuary phase of its life.

New myxosporeans parasitizing Phractocephalus hemioliopterus from Brazil: morphology, ultrastructure and SSU-rDNA sequencing.

Myxozoans are a diverse group of parasitic cnidarians, with some species recognized as serious pathogens to their hosts. The present study describes 2 new myxobolid species (Myxobolus figueirae sp. nov. and Henneguya santarenensis sp. nov.) infecting skin and gill filaments of the Amazonian pimelodid fish Phractocephalus hemioliopterus, based on ultrastructural, histology and phylogenetic analysis. The fish were caught in the Amazon River, Pará, Brazil. The plasmodial development of M. figueirae sp. nov. was in the dermis and those of H. santarenensis sp. nov. were of the intralamellar type. For both species, the plasmodia were surrounded by a connective tissue layer, but there was no inflammatory infiltrate. For M. figueirae sp. nov., mature spores were ovoid measuring 9.1 to 10 (9.5 ± 0.3) µm in length, 5.8 to 6.9 (6.4 ± 0.3) µm in width and 4.4 to 4.5 (4.5 ± 0.1) µm in thickness. Two polar capsules were elongated and of unequal size. For H. santarenensis sp. nov., mature spores were ellipsoidal in the frontal view, measuring 26.3 to 36.1 (31.9 ± 3) µm in total length, 9.6 to 11.9 (10.8 ± 0.5) µm in body length, 3.7 to 4.9 (4.3 ± 0.3) µm in width and 16.6 to 25.6 (21 ± 3.1) µm in caudal process. The polar capsules were elongated and of equal size. Phylogenetic analysis, based on partial small subunit ribosomal DNA (SSU rDNA) sequences and using the closest myxozoan sequences to each one of the species studied here based on previous GenBank data, showed M. figueirae sp. nov. and H. santarenensis sp. nov. clustering in distinct lineages. While H. santarenensis sp. nov. clustered in a well-supported subclade composed of Henneguya species that infect gills of South American pimelodid hosts, M. figueirae sp. nov. clustered in a weakly supported subclade containing parasite species of bryconid hosts.

Hematological alterations in Astyanax altiparanae (Characidade) caused by Lernaea cyprinacea (Copepoda: Lernaeidae).

This study describes the hematological alterations in Astyanax altiparanae associated with infestation with Lernaea cyprinacea. The study was carried out in a lagoon of the Mogi-Guaçu River, in the municipality of Pirassununga, in the state of São Paulo, Brazil. Of 46 fish examined, 45.6% had their integument infested by L. cyprinacea, with a mean intensity of 4.9 parasites per fish and a mean abundance of 2.2, giving a total of 139 recovered crustaceans. The abundance of L. cyprinacea correlated positively with the length and weight of the hosts, and the intensity of infestation was higher in female hosts. Macroscopic observation of lesions associated with the parasite showed a severe inflammatory reaction around the site of attachment of L. cyprinacea, associated with a lower relative condition factor and blood parameters. The hematocrit, number of red blood cells and thrombocytes were higher in non-parasitized than in parasitized fish. However, the hemoglobin concentration, hematimetric indices and the number of white blood cells were not influenced by infestation.

Behavioral changes caused by Austrodiplostomum spp. in Hoplias malabaricus from the São Francisco River, Brazil.

Traira (Hoplias malabaricus) is a neotropical fish that is widely distributed in freshwater environments in South America. In the present study, we documented the occurrence of metacercariae of Austrodiplostomum spp. (Diplostomidae) in the eyes and cranial cavity of H. malabaricus and described parasite-induced behavioral changes in the host. The fish were collected from the upper São Francisco River, in the Serra da Canastra mountain range, Minas Gerais, transported alive to the laboratory, observed for 2 weeks, and subsequently examined for parasites. Of the 35 fish examined, 28 (80 %) had free metacercariae in the vitreous humor (mean intensity=95.4; mean abundance=76.3), and 24 (68.57 %) had free metacercariae in the cranial cavity, mainly concentrated below the floor of the brain, at the height of the ophthalmic lobe (mean intensity=12.91; mean abundance=8.85). Specimens of H. malabaricus with a high intensity of infection in the brain displayed changes in swimming behavior.

Hematological alterations caused by high intensity of L3 larvae of Contracaecum sp Railliet & Henry, 1912 (Nematoda, Anisakidae) in the stomach of Hoplias malabaricus in lakes in Pirassununga, São Paulo.

The objective of the present study was to discover the hematological indices of Hoplias malabaricus infected by larvae of Contracaecum sp. A total of 105 fish were collected from two lakes located in the municipal district of Pirassununga, São Paulo, Brazil, of which 95.2% were infested by L3 larvae of Contracaecum sp., with an average intensity of 348.7 ± 231.55 helminths/fish. A total of 76 fish were analyzed to establish hematological parameters. Following analysis, it was found that there was a significant difference between hematological parameters Hct, erythrocytes (Er), thrombocytopenia (p = 0.01), and Hb (p = 0.02) in lakes A and B, while there was no significant difference for leukocyte (p = 0.68), mean corpuscular volume, mean corpuscular hemoglobin (p = 0.06), and mean corpuscular hemoglobin concentration (p = 0.47). The intensity of infection correlated negatively with Er (r(s) = -0.42; p < 0.01) and positively for (r(s) = 0.48; p < 0.01). The high intensity of infection by Contracaecum sp. in H. malabaricus did not affect the health of the fish despite causing alterations in hematological variables.