The domestic chicken, Gallus gallus domesticus Linnaeus, 1758, is an important component of theagribusiness segment, and Brazil is one of the world's largest broiler producers and exporters. The present study aimed to characterize the composition and structure of the helminth community of backyard chickens, G. g. domesticus, in Seropédica, Rio de Janeiro, Brazil. Fifty-five adult chickens were studied. The overall helminth species richness was 12. The nematodes Capillaria sp. And Heterakis gallinarum (Schrank, 1788), recovered from small intestine and cecum, respectively, presented the highest prevalence and mean abundance. In addition, these species presented the highest values of frequency of dominance. The helminth species Amoebotaenia cuneata (von Linstow, 1872) – Raillietina tetragona (Molin, 1958); and Davainea proglottina (Davaine, 1860) – A. cuneata; and H. gallinarum – Ca...

Hassalstrongylus luquei n. sp. is described from the small intestine of Euryoryzomys russatus (Rodentia: Sigmodontinae) collected in the Atlantic Forest (Rio de Janeiro State, Angra dos Reis, Brazil). The genus Hassalstrongylus includes 16 Neotropical species. The main characters of new species are subsymmetrical caudal bursa with a type 2-2-1, rays 8 branching at midlength of dorsal trunk, right lateral trunk larger than the left and the longest spicules in the genus. Only three species of Hassalstrongylus have the rays 8 not emerging at the base trunk, these are: H. mazzai; H. aduncus; and H. echalieri. However, the present species is distinguished from H. mazzai by having the dorsal rays divided at fourth part of the trunk, H. bocqueti by having rays 5 bifurcating at third part of trunk and H. echalieri by having a pattern of 2-2-1.

This study provides a comprehensive morphological redescription of Mastophorus muris Gmelin, 1790, a spirurid nematode, based on specimens collected from Rattus norvegicus Berkenhout, 1769 in Nova Iguaçu municipality, Rio de Janeiro, Brazil. Employing optical and scanning electron microscopy, we detailed morphological characteristics, including previously unreported features such as a pair of ad-cloacal papillae and details of pseudolabia teeth. Additionally, we report a new geographical distribution for M. muris in Brazil. The low prevalence of M. muris observed in this study highlights the potential impact of anthropic changes on parasite distribution. Further investigations, including molecular analyses, are necessary to elucidate the taxonomic complexity and host-parasite relationships within the genus Mastophorus

Interface areas between urban and sylvatic environments increase the contact between humans and wild animals, and may favour the transmission of zoonoses. The aim of this study was to describe the helminth fauna of a small mammal community in an urban-sylvatic interface area of the Brazilian Atlantic Forest. Twenty helminth species were recovered in six species of small mammals. Parasite sharing was observed in two helminth species among the marsupials. This study is the first report of a helminth infection for the marsupial Monodelphis americana (Müller, 1776). This is the first report of the nematodes Aspidodera raillieti Travassos, 1913, Viannaia hamata Travassos, 1914 and Trichuris sp. parasitizing the marsupial Marmosa paraguayana (Tate, 1931). None of the helminth species found has been reported to infect humans.