Hepatozoon parasites (Apicomplexa: Hepatozoidae) in fish Hoplias aimara (Characiformes, Erythrinidae) from the Eastern Amazon, Brazil.

This study reports the occurrence of parasites belonging to the Hepatozoon genus in fish Hoplias aimara from the Eastern Amazon. Fish (n = 54) were sampled from the Falsino River, located in the Amapá National Forest (FLONA), in the state of Amapá, northern Brazil. Fresh liver preparations were examined in the field between a slide and a coverslip under a light microscope. Cysts containing Hepatozoon cystozoites were observed in the liver of 5 (9%) out of 54 H. aimara individuals. The cysts were ovoid (mean dimensions 10.28 × 9.8 µm), presenting up to four elongated cystozoites (mean dimensions 11.04 × 1.68 µm), containing 1 to 4 residual bodies of different sizes. A single liver sample containing cysts was submitted to DNA extraction and PCR analyses based on a fragment of the 18S rRNA gene. The sequencing revealed a 465 bp fragment exhibiting 99% query coverage, 0.0 E-value, and 98.7% identity with Hepatozoon caimani (MF322538 and MF322539), detected in caimans (Caiman yacare) from Brazil. This is the first report of the occurrence of cysts containing Hepatozoon cystozoites in free-living fishes.

Phylogenetic analysis of chelonian hemogregarines reveals shared species among the Amazonian freshwater turtle Podocnemis spp. and provides a description of two new species of Haemogregarina.

This study describes two new species of the genus Haemogregarina living in the Amazonian freshwater turtles Podocnemis expansa and Podocnemis sextuberculata. Haemogregarina species isolated from P. expansa have been characterized by the presence of encapsulated, folded immature gamonts, with the parasitophorous vacuole and fragmented chromatin located in the central region. In Haemogregarina found in P. sextuberculata, curved immature gamonts were observed inside a parasitophorous vacuole, with small, slightly arched meronts with rounded nuclei, and mature gamonts with trapezoid-shaped condensed nuclei. The novel 18S rRNA sequences obtained in this study clustered within a well-supported clade composed of hemogregarines isolated from other neotropical freshwater turtles from the families Podocnemididae and Geoemydidae. The hemogregarines found in this study were compared to Haemogregarina podocnemis from Podocnemis unifilis and Haemogregarina sp. from Podocnemis expansa, based on morphological, morphometric, and molecular data. The analysis supports the new species Haemogregarina karaja sp. nov. isolated from P. expansa and Haemogregarina embaubali sp. nov. found in P. sextuberculata.

Hepatozoon cevapii (Apicomplexa: Hepatozoidae) in the Thamnodynastes lanei snake (Colubridae, Tachymenini) from the Eastern Amazon, Brazil.

The aim of the present study was to verify the occurrence of hemogregarines in the colubrid snake Thamnodynastes lanei from the eastern Amazon region of Brazil. Intraerythrocytic gamonts with mean dimensions of 14.8 ± 1.8 × 4.0 ± 0.7 µm and encapsulated gamonts with mean dimensions of 15.3 ± 1.1 × 4.8 ± 0.5 µm were observed. Through morphological and molecular data based on the partial 18S rDNA gene, the parasite was identified as Hepatozoon cevapii, originally described in the viperid snake Crotalus durissus terrificus from the southeast region of Brazil. Thus, the findings of the present study extend the geographic range of H. cevapii and provide novel Hepatozoon-snake associations.

A new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from the twist-necked turtle Platemys platycephala (Schneider) (Testudines: Chelidae) in Brazil.

A new coccidian species of the genus Isospora Schneider 1881 (Apicomplexa, Eimeriidae) is reported from a single specimen of chelid turtle, Platemys platycephala (Schneider, 1792), obtained in a flooded area of the Amazonian municipality of Altamira, in Pará State, northern Brazil. The oöcysts of Isospora platemysi n. sp. are subspheroidal, 19.0-24.0 × 22.5-18.5 (22.6 × 20.8) µm in size [length/width ratio 1.0-1.1 (1.1)], with a colourless wall, 1.0-1.9 (1.4) wide, with two smooth layers; polar granule is present, oöcyst residuum and micropyle are both absent. The sporocyst is ovoidal, 10.0-12.1 × 8.0-10.0 (11.0 × 9.1) µm [length/width ratio 1.1-1.3 (1.2), with a knob-like Stieda body. Sub-Stieda body is present, rounded irregular-trapezoidal; para-Stieda body is absent. Sporocyst residuum is dispersed and composed of granules of differing sizes. This is only the fifth record of Isospora in chelonians, and the first report of a coccidian parasite of the genus Platemys.