A new species of Aplectana Railliet & Henry, 1916 (Nematoda: Cosmocercidae) in the Brazilian Amazon and the taxonomic status of Aplectana longa.

Nematodes of the genus Aplectana Railliet & Henry, 1916 are common parasites of the digestive tract of amphibians and reptiles in the Neotropical region. During a parasite survey on Boana boans (Linnaeus, 1758), we found specimens of nematodes with Aplectana characteristics. We observed a set of characteristics that differs the species of our study from its congeners, and the present study describes a new species of Aplectana parasite of B. boans using light microscopy and scanning electron microscopy. Aplectana pella n. sp. has lateral alae and somatic papillae in males and females; males have equal short spicules, and the gubernaculum is absent. The arrangement of pairs of caudal papillae also differs from other species (2 precloacal,1 adcloacal, and 5 postcloacal+1 unpaired). In females, the vulva is simple, with non-prominent lips, and equatorial. This is the first record of the genus Aplectana parasitizing B. boans and the 58th species described for this genus. Additionally, we added the precloacal papillae pattern of A. delirae, and based on morphological and morphometric characteristics, we propose the reallocation of Aplectana longa to the genus Oxyascaris.

A new species of Oxyascaris Travassos, 1920 (Nematoda: Cosmocercoidea) parasite of Leptodeira annulata (Serpentes: Colubridae) from Brazil, with a key to the species of the genus.

During a helminthological survey of snakes in the Cerrado Biome in Maranhão State, Brazil, we found intestinal nematodes in Leptodeira annulata (Linnaeus), belonging to the genus Oxyascaris Travassos, 1920. We observed that the specimens found are distinct from their congeners by the combination of presented characters, mainly the cuticular expansion at the anterior region of the body, presence of a single papilla at the anterior cloacal lip, number, and arrangement of caudal papillae, presence of somatic papillae along body cuticle, as well as some morphometric characters. Thus, we describe the new species using light and scanning electron microscopy and, revise the morphological characters used to identify Oxyascaris spp. and propose a key to the species of the genus. Therefore, we describe the seventh species in the genus, the second reported to parasitize snakes, the sixth species recorded in Brazil, and the first described in the Cerrado Biome.

New species of Serpinema (Nematoda: Camallanidae) from the scorpion mud turtle Kinosternon scorpioides (Testudines: Kinosternidae) from eastern Amazon, Brazil.

The genus Serpinema Yeh, 1960 allocates parasitic nematodes of freshwater turtles distributed across the Oriental, Neotropical, and Palearctic regions. Five of 10 valid species of the genus Serpinema occur in the Neotropical region, and three have been recorded parasitizing Kinosternon scorpioides Linnaeus, 1766. In the present work, we describe a new species of Serpinema, a gastrointestinal parasite of K. scorpioides from the Brazilian Amazon, using light and scanning electron microscopy. Serpinema pelliculatus n. sp. differs from other species of the genus by the number and distribution of caudal papillae and spicule morphology. The new species is the seventh recorded for the Neotropical region.

A NEW SPECIES OF PNEUMOATRACTIS (COSMOCERCOIDEA: ATRACTIDAE) FROM TWO SPECIES OF FRESHWATER TURTLES FROM THE BRAZILIAN AMAZON.

The monotypic genus PneumoatractisBursey, Reavill, and Greiner, 2009 was erected to allocate nematodes collected from the lungs of the freshwater turtle Podocnemis unifilis Troschel. During a helminthological survey of parasites from freshwater turtles of Tocantins and Xingu rivers, Pará State, eastern Amazon, Brazil, we found nematodes parasitizing the stomach and large intestine of Po. unifilis and Podocnemis expansa Schweigger. We assigned them to a new species of Pneumoatractis, which is described herein. Pneumoatractis gibbonsae n. sp. resembles Pneumoatractis podocnemis by the morphology of the oral opening, the position of the excretory pore, and the lanceolate shape of the spicules, but differs from it in males by having 10 pairs of caudal papillae plus 1 unpaired anterior to cloacal lip, different length of the right spicule, and short gubernaculum; it differs in females by the distances of vulva and anus from the posterior end respectively. We found the new species in a different infection site from that of the type species. Thus, this is the second species of Pneumoatractis described in Po. unifilis and the first in Po. expansa.

"Revisiting the past": a redescription of Physaloptera retusa (Nemata, Physalopteridae) from material deposited in museums and new material from Amazon lizards.

Physaloptera Rudolphi, 1819 is a genus of nematodes that includes approximately 100 species parasitic in vertebrates around the world. From these, approximately 30 occur in the Neotropical region, with nine reported from neotropical reptiles. Physaloptera spp. are recognized by their distinct morphology of the apical end and characters of the reproductive system. However, despite the fact that the morphological characters for species diagnosis have been firmly established, we frequently find identification problems regarding poorly detailed descriptions and poorly preserved specimens. These may lead to taxonomic incongruencies. Physaloptera retusa (Rudolphi, 1819) is the most common species of the genus and has been reported from several species of neotropical reptiles. Based on our reexaminations of nematode specimens identified as P. retusa from different museum collections, we provide a detailed redescription including the type material, voucher specimens and new specimens recovered currently and showed in this study with new morphological data obtained using light and scanning electron microscopy tools.

DO ENVIRONMENTAL AND HOST VARIABLES INFLUENCE THE PARASITE COMMUNITY OF LEPTODACTYLUS FUSCUS (ANURA: LEPTODACTYLIDAE) IN THE AMAZON REGION?

Leptodactylus fuscus is a small-sized species widely distributed across South America. However, so far, no works have been addressed to analyze if biotic and abiotic factors may influence the parasite community in this species. Thus, the present work aims to describe the composition and structure of the parasite community and evaluate if biotic and environmental factors correlated to the distribution of the parasite community for this host. We collected 36 L. fuscus specimens from February 2018 to January 2019. The hosts were necropsied, and parasites were collected and identified. To test the effect of environmental variables (temperature, humidity, and precipitation) and morphological characters of the host (snout-vent length and body weight) on helminths of L. fuscus we used a multivariate distance matrix regression (MDMR). We found 10 helminth taxa: Aplectana sp., Aplectana membranosa, Cosmocercidae larvae, Mesocoelium sp., Mesocoelium aff. monas, Mesocoelium aff. sociale, Oswaldocruzia sp., Oxyascaris sp., Ortleppascaris sp. larvae, and Schrankiana formosula. In our study, the helminth community showed an aggregate pattern, and we did not observe a statistically significant correlation of body size and mass of the hosts regarding parasite abundance and richness. Thus, this study represents the first report of M. sociale, A. membranosa, and Ortleppascaris sp. larvae for L. fuscus and new locality reports. We conclude that there is no correlation between variables analyzed and the structure and composition of the parasite community of L. fuscus.

Do host habitat use and cospeciation matter in the evolution of Oswaldocruzia (Nematoda, Molineidae) from neotropical amphibians?

The genus Oswaldocruzia Travassos, 1917 includes approximately 90 species that are parasitic on amphibians and reptiles around the world, of which 43 occur in the neotropical region. However, molecular data supporting the taxonomic status of most species of the genus are scarce, and their phylogenetic relationships remain unknown. Using specimens of four molineid taxa (Oswaldocruzia belenensis Santos, Giese, Maldonado Jr. and Lanfredi, 2008; Oswaldocruzia chabaudi Ben Slimane & Durette-Desset, 1996, Oswaldocruzia chambrieri Ben Slimane & Durette-Desset, 1996 and Kentropyxia hylae Feitosa, Furtado, Santos and Melo, 2015) from amphibian hosts collected in different regions of Pará, Brazil, we conducted morphological studies, molecular analyses and phylogenies (maximum likelihood and Bayesian inference) using the cytochrome c oxidase subunity I (Cox1) gene. The newly generated sequences were compared with those of ten publicly available Cox1 sequences of Oswaldocruzia from Mexico. Our findings demonstrated significant differences between the sequences of amazonian specimens and sequences from specimens collected in Mexico, and we suggest that host-parasite cospeciation or habitat use might be related to molineid evolution in amphibian hosts. Additionally, this work presents new hosts and new geographical records for species of Oswaldocruzia from the neotropics.

Redescription of Oswaldocruzia chambrieri (Strongylida: Molineidae) from Rhinella margaritifera (Anura: Bufonidae) in Caxiuanã National Forest, Brazil.

Oswaldocruzia chambrieri Ben Slimane et Durette-Desset, 1993 is redescribed from specimens collected from the small intestine of the South American common toad, Rhinella margaritifera, from Caxiuanã National Forest in Pará, Brazil, using light and scanning microscopy and molecular analysis of Cytochrome Oxidase I (COI) - coding regions of DNA. The discovered nematodes are characterized by a type III caudal bursa with two papillae, rays 4 with a median groove, and spicules divided into a blade, a shoe and a fork. Cervical alae are absent, the cephalic vesicle is divided into two portions, and the synlophe has low ridges without chitinous supports. The present study establishes the Caxiuanã National Forest as a new location for O. chambrieri, which had previously been reported as a parasite of R. margaritifera in Ecuador, uses light microscopy and scanning electron microscopy (SEM) to identify new morphological characters of the species and represents the second molecular sequence deposited for the Oswaldocruzia genus.