Gleasonian structure in the helminth metacommunity of the opossum Didelphis albiventris in two extremes of the Atlantic Forest.

Didelphis albiventris is the opossum with the largest geographic distribution in Brazil and has a wide spectrum of helminth parasites. This study aimed to describe the species composition and analyse the structure of helminth communities of D. albiventris in two extremes of the Atlantic Forest in Brazil. The influence of host sex, body mass, age, helminth species richness and locality on the abundance and prevalence of the most prevalent helminth species was investigated. Ninety-five per cent of the animals were infected with at least one species. Nine helminth species were found: the nematodes Aspidodera raillieti, Cruzia tentaculata, Trichuris didelphis and Trichuris minuta in the large intestine; Turgida turgida in the stomach; Travassostrongylus orloffi and Viannaia hamata; and the trematodes Brachylaima advena and Rhopalias coronatus in the small intestine. Three helminth morphospecies were also recovered: the nematodes Hoineffia sp. and Viannaia sp. and a cestode in the small intestine. Cruzia tentaculata and V. hamata were the species with the highest mean abundances and intensities, while the most prevalent species were A. raillieti, C. tentaculata, T. turgida and V. hamata, forming the central nucleus of the helminth component community. The analysis of the helminth metacommunity structure indicated a Gleasonian pattern for the total set of infracommunities, corroborating the beta diversity indices, which indicated more species replacement than loss between localities and infracommunities, although at a low level. The results indicated a stronger influence of host attributes than geographical distance on the community structure.

Boehmiella wilsoni (Nematoda, Heligmosomoidea, Boehmiellidae fam. nov.), found in Amazonian rodents.

The genus Boehmiella was initially described as a member of the family Trichostrongylidae. Subsequently, it was assigned to the subfamily Haemonchinae in the family Haemonchidae. We analyzed parasites of spiny tree-rats, Mesomys hispidus, collected in the Amazon rainforest, which were identified as B. wilsoni based on integrative taxonomy. Using morphology, morphometry, and scanning electron microscopy (SEM), we added new data to the original description of the species. We also inferred phylogenetic hypotheses for its relationships within the Trichostrongylina, based on partial nuclear 18S and 28S rRNA genes, through Maximum Likelihood and Bayesian analyses. In conclusion, B. wilsoni does not belong to the family Haemonchidae, nor is it closely related to any other trichostrongylin family, and therefore, we propose the establishment of a new family, Boehmiellidae fam. nov., to which the genus Boehmiella is allocated.

A new species of Physaloptera (Nematoda: Spirurida) from Proechimys gardneri (Rodentia: Echimyidae) from the Amazon rainforest and molecular phylogenetic analyses of the genus.

Nematodes of the genus Physaloptera are globally distributed and more than 100 species are known. Their life cycle involves insects, including beetles, cockroaches and crickets, as intermediate hosts. This study describes a new species of Physaloptera and reports molecular phylogenetic analyses to determine its relationships within the family Physalopteridae. Physaloptera amazonica n. sp. is described from the stomach of the caviomorph rodent Proechimys gardneri collected in the Amazon rainforest in the state of Acre, Brazil. The species is characterized by the male having the first and second pair of sessile papillae asymmetrically placed, lacking a median papilla-like protuberance between the third pairs of sessile papillae, differentiated by size and shape of the spicules, while females have four uterine branches. For both nuclear 18S rRNA and MT-CO1 gene-based phylogenies, we recovered Turgida sequences forming a clade nested within Physaloptera, thus making Physaloptera paraphyletic to the exclusion of Turgida, suggesting that the latter may have evolved from the former monodelphic ancestral state to a derived polydelphic state, or that some species of Physaloptera may belong to different genera. Relationships between most taxa within Physaloptera were poorly resolved in our phylogenies, producing multifurcations or a star phylogeny. The star-like pattern may be attributed to evolutionary processes where past simultaneous species diversification events took place. Physaloptera amazonica n. sp. formed an independent lineage, separately from the other species of Physaloptera, thus supporting the status of a new species. However, all molecular data suggested a closer relationship with other Neotropical species. In conclusion, we added a new species to this already largely diverse genus Physaloptera, bringing new insights to its phylogenetic relationships. Further analyses, adding more species and markers, should provide a better understanding of the evolutionary history of physalopterids.

Metacommunity structure of the helminths of the black-eared opossum Didelphis aurita in peri-urban, sylvatic and rural environments in south-eastern Brazil.

Among the Brazilian marsupials, the species of the genus Didelphis are the most parasitized by helminths. This study aimed to describe the species composition and to analyse the helminth communities of the Atlantic Forest common opossum Didelphis aurita at infracommunity and component community levels using the Elements of Metacommunity Structure Analysis, considering peri-urban, sylvatic and rural environments in the state of Rio de Janeiro, Brazil. Seventy-three specimens of D. aurita were captured during the study. Fourteen species of helminths were collected: nine of the phylum Nematoda (Trichuris minuta, Trichuris didelphis, Globocephalus marsupialis, Heterostrongylus heterostrongylus, Travassostrongylus orloffi, Viannaia hamata, Aspidodera raillieti, Cruzia tentaculata and Turgida turgida); four of the phylum Platyhelminthes (three species of Trematoda, Duboisiella proloba, Brachylaima advena and Rhopalias coronatus, and one species of the class Cestoda); and one species of the phylum Acanthocephala (Oligacanthorhynchus microcephalus). More than 95% of the animals were infected with parasites. The most abundant parasite species were V. hamata, T. turgida, C. tentaculata and T. orloffi. The nematodes T. turgida, C. tentaculata and A. raillieti were the most dominant species in the three environments. The analysis of the metacommunity structure indicated a structured pattern as a function of the environmental gradient, but only when all localities were considered together. At the infracommunity and component community levels, quasi-nested and nested structures with stochastic species loss were observed, respectively. The results indicate that the settlement of helminth species in the opossums can be attributed to the heterogeneity among individual hosts in relation to their exposure to parasites and to extrinsic factors, which vary among habitats, considering a regional scale. On a local scale, the characteristics of this host species may promote homogenization among individual hosts in terms of their exposure to the helminths. This study constitutes a new host record for the species G. marsupialis and T. didelphis and represents a pioneering investigation of the helminth metacommunity of a Neotropical marsupial.

Hantavirus pulmonary syndrome and rodent reservoirs in the savanna-like biome of Brazil's southeastern region.

This paper describes the diversity of rodent fauna in an area endemic for hantavirus cardiopulmonary syndrome (HCPS) in Brazil, the population dynamics and the relationship of rodents with hantavirus in the Cerrado (savanna-like) biome. Additionally, an analysis is made of the partial S segment sequences of the hantaviruses obtained from serologically confirmed human HCPS cases and from rodent specimens. Rodents were collected during four campaigns. Human serum samples were collected from suspected cases of HCPS at hospitals in the state of Minas Gerais. The samples antibody-reactive by ELISA were processed by RT-PCR. The PCR product was amplified and sequenced. Hantavirus was detected only in Necromys lasiurus, the wild rodent species most prevalent in the Cerrado biome (min-max: 50-83·7%). All the six human serum samples were hantavirus seropositive and five showed amplified PCR products. The analysis of the nucleotide sequences showed the circulation of a single genotype, the Araraquara hantavirus. The environmental changes that have occurred in the Cerrado biome in recent decades have favoured N. lasiurus in interspecific competition of habitats, thus increasing the risk of contact between humans and rodent species infected with hantavirus. Our data corroborate the definition of N. lasiurus as the main hantavirus reservoir in the Cerrado biome.

Changes in the calcium metabolism of Biomphalaria glabrata experimentally infected with Angiostrongylus cantonensis.

Levels of calcium in the haemolymph and reserves in the shell of Biomphalaria glabrata experimentally infected by Angiostrongylus cantonensis were determined for the first time. At the same time, histochemical analyses of the digestive gland of infected and uninfected snails were performed to better understand the possible changes in metabolism of calcium in these organisms. After 1, 2 and 3 weeks of infection, the snails were dissected for collection of haemolymph and separation of tissues. The highest calcium concentrations in the haemolymph were found 2 weeks after infection, with a 39.61% increase in relation to the respective control group. However, there was a significant reduction in the concentration of this ion in the haemolymph of infected snails after 1 week of infection in relation to the uninfected specimens. In parallel, intense hypocalcification was shown in the shell of infected snails 1 and 2 weeks after infection, differing significantly in relation to the respective control groups. Morphological changes in the digestive gland of infected snails were also observed, confirming the role of this ion as an important element in the parasite encapsulation process.