Endoparasite community of anurans from an altitudinal rainforest enclave in a Brazilian semiarid area

Does the body size, sex, and reproductive modes of leaf litter anurans affect the diversity of parasites?

We describe the composition of endoparasites associated with leaf litter anurans from an Atlantic Forest area, in southeastern Brazil. We tested if body size, sex, and reproductive modes of anuran hosts influence endoparasite abundance and richness. We sampled 583 individuals from 11 anuran species and recorded 1,600 helminths from 14 taxa. The helminths that infected the greatest number of anuran host species were the nematodes Cosmocerca parva (8 spp.), Physaloptera sp. (8 spp.), and Cosmocerca brasiliense (7 spp.), and the most abundant helminth species were Physaloptera sp. (14.6%), Cosmocerca brasiliense (13.7%) and Cosmocerca parva (12.6%). Both helminth abundance and richness were positively affected by anuran body size and dependence on water for reproduction. Larger hosts can contain a higher abundance of parasites because they may provide more physical space than smaller ones, or it can simply be a function of age. Besides, parasite species richness can be highly correlated with the amount of time a host spends in association with aquatic habitats, a conservative aspect of both parasite and host natural history. Within host species, there was a positive and significant influence of body size on helminth abundance. Haddadus binotatus females had greater helminth abundance than males, probably due to sex-related differences in behavior and/or in physiology. Our data suggest that reproductive modes could also influence helminth infection parameters in other anuran communities and should be considered in detail in future analyses.

Centrorhynchus spp. (Acanthocephala) in South America: new anuran record and checklist of vertebrate hosts

The aim of this study was to record Centrorhynchus sp. associated with the exotic species Aquarana catesbeiana (bullfrog) in southern Brazil and to present a checklist of vertebrate hosts in South America. Twenty-nine adults and juveniles of A. catesbeiana were collected in Capão do Leão, state of Rio Grande do Sul, Brazil, between October 2019 and December 2020. We found 275 specimens of Centrorhynchus sp. cystacanths in the stomach musculature and coelomic cavity of 55.1% of hosts (16). There was no significant differences in the prevalence and mean intensity of infection with cystacanths when compared males and females of A. catesbeiana. The prevalence was significantly higher in adults than in juveniles. The checklist presents 106 species of vertebrate hosts and 14 taxa of Centrorhynchus recorded in nine South American countries. Avian were the main definitive hosts of Centrorhynchus spp. and snakes Dipsadidae, anurans Hylidae and Leptodactylidae the main paratenic hosts in South America. This is the first record of Centrorhynchus cystacanths in A. catesbeiana in the South America. The study provides tools to help understand the parasitic relationships between species of Centrorhynchus and A. catesbeiana and other hosts in areas where bullfrog have been introduced.

Pattern of anuran infection by acanthocephalans from the Cerrado, Northeastern Brazil with a summary for South America

In Brazil, acanthocephalans parasitise anurans in several biomes. In the present study, we performed an analysis of acanthocephalan infections across 175 anuran individuals from the Cerrado biome, belonging to ten species: Boana raniceps, Pithecopus hypochondrialis, Scinax fuscomarginatus, Scinax x-signatus, Leptodactylus pustulatus, Leptodactylus macrosternum, Leptodactylus vastus, Physalaemus cuvieri, Adenomera hylaedactyla, and Elachistocleis piauiensis. We also verified the specificity of the parasites using the STD* index. Additionally, we conducted a survey of acanthocephalan infection in anurans in South America. The studied assemblage in the Brazilian Cerrado presented 57 parasitised hosts of 175 specimens (overall prevalence: 32.6%). In total, 437 acanthocephalans cystacanths were recorded, among which 286 presented the same morphotype but could not be identified, 148 belonged to the genus Centrorhynchus, and three belonged to Oncicola. Unidentified acanthocephalans had a higher prevalence in L. vastus (53.85%) and the highest intensity was in L. pustulatus (17±16). The highest prevalence of Centrorhynchus sp. was in the species S. fuscomarginatus (28.57%), while the highest intensity was observed in L. vastus (111). The taxon Oncicola sp. it had a prevalence of 3.23% and an intensity of 3 only in S. x-signatus. The highest specificity was recorded for Oncicola sp. (STD*= 1), whereas the lowest was found in Centrorhynchus sp. (STD*= 2.21). Finally, according to the survey for South America, we found ten records of acanthocephalan taxa parasitizing 58 species of anurans distributed in seven countries (Brazil with the most records).

Diversity of Acanthocephala parasites in Neotropical amphibians

Acanthocephalans constitute a small taxonomic group related to rotifers and specialized in a parasitic lifestyle. Anurans act as paratenic and definitive hosts and infections always occur trophically. Our objective is to describe and summarize the richness of acanthocephalans in Neotropical anurans. We conducted a literature review in the main research databases, compiling data published until August 2021. We identified 66 articles with records of acanthocephalan-anuran association, 53.03% were carried out in Brazil. We detected 108 species of anurans from 11 families parasitized by acanthocephalans. With the exception of Bufonidae, Hylidae and Leptodactylidae, which are relatively well-studied families, interaction with acanthocephalans remains largely unexplored for most anuran species. We found six families of acanthocephalans: Centrorhynchidae, Echinorhynchidae, Oligacanthorhynchidae, Cavisomidae, Neoechinorhynchidae and Plagiorhynchidae. Centrorhynchidae and Echinorhynchidae presented the largest number of taxa associated with anurans. The largest number of records corresponded to acanthocephalans in the larval stage (cystacanths), for which anurans act as paratenic hosts. We observed a lack of specific taxonomic resolution in the identifications of most reports, because a large part of the records in the larval stage make morphological identification difficult. Brazil, Mexico, Paraguay, Argentina, Ecuador and Peru are the countries with the most records, while Costa Rica, Venezuela, Colombia, Chile and Uruguay exhibited the lowest publication numbers, resulting in gaps in the distribution of acanthocephalans. We expanded the known number of anuran species parasitized by acanthocephalans, compared to the last published review. Overall, we aim to contribute to the understanding of diversity within this intriguing but understudied group.

New insights into a poorly known parasite, Dero lutzi (Oligochaeta: Naididae), associated with tree frogs of the genus Scinax: morphological evaluation and genotypic data

The oligochaete Dero lutzi follows a life strategy that alternates between free-living periods in aquatic environments and endoparasitic phases. Most occurrences of D. lutzi in anurans are reported in species with arboreal habits, with studies limited to the recording of the oligochaete's presence in the host. Our study recovered specimens of D. lutzi from the tree frogs Scinax fuscovarius and Scinax. nasicus. We performed a morphological assessment of the parasite using light microscopy, for the first time, scanning electron microscopy. Molecular characterization of D. lutzi was carried out using the mitochondrial gene 16S rRNA and the nuclear gene 28S rRNA. Additionally, a phylogenetic tree was constructed to assess the species´position in relation to other group members. In our results, we confirmed the phenotypic morphological characteristics of the endoparasitic phase of D. lutzi. We also presented its phylogenetic position with other oligochaetes in the group, demonstrating the proximity between the endoparasite D. lutzi and the free-living oligochaete D. superterrenus.

Effect of altitude and spatial heterogeneity on the host-parasite relationship in anurans from a remnant humid forest in the brazilian semiarid

In the present study, we investigated the effect of habitat heterogeneity, elevation gradient, and phylogenetic distance of host species on the abundance and richness of anuran endoparasites, assuming that parasites follow the distribution of their hosts independently of environmental variation. We collected 192 anurans distributed in three altitude ranges: 100-200 m, 400-500 m, and 700-800 m. We performed discriminant principal component analysis to analyze the interrelationships between environmental heterogeneity and the distribution of parasite and host species in the formation of species groups in each altitude range. We estimated the niche width and parasite overlap, using host species as a variable, and assessed whether parasite abundance is more influenced by historical (distance host phylogeny) or ecological effects in each altitude category and overall. Finally, we use network analyses to understand how interactions between parasites and hosts are formed along the altitude gradient. We found 22 parasite species, and the overall prevalence of infection was 74%. In our study, we did not identify environmental (altitude gradients and heterogeneity) or phylogenetic effects acting on the parasite species diversity. Overall, our results suggest that the parasites are distributed following the dispersal of their hosts and are dispersed among most anuran species.