Morphology, genetic characterization and phylogeny of Aplectana dayaoshanensis n. sp. (Nematoda: Ascaridida) from frogs

Chen, Hui-Xia; Ni, Xue-Feng; Gu, Xiao-Hong; Sinsch, Ulrich; Li, Liang

doi:10.1016/j.meegid.2021.105123

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…In Rhigonematomorpha, only 21 nominal species have been genetically characterized [14-17, 19, 20], and most of the data available are represented by the 18S and 28S sequences, which are commonly used for molecular phylogeny of higher taxa within Nematoda [21][22][23][24][25][26]. Although the nuclear internal transcribed spacer (ITS) region and the mitochondrial cox1 and cox2 genes are widely used as powerful and practical genetic markers for revealing sibling or cryptic species, delimiting phenotypic variation and identifying species in the infraorders Ascaridomorpha, Spiruromorpha and Oxyuridomorpha [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], they have been scarcely employed in studies pertaining to Rhigonematomorpha species. Consequently, no current knowledge on the effectiveness of ITS, cox1 and cox2 as genetic markers for identification of Rhigonematomorpha nematodes is available.…”

Section: Introductionmentioning

confidence: 99%

Molecular identification of a new species of Rhigonema (Nematoda: Rhigonematidae) and phylogenetic relationships within the infraorder Rhigonematomorpha

et al. 2022

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Background The infraorder Rhigonematomorpha comprises a group of obligate parasitic nematodes of millipedes (Arthropoda: Diplopoda). The current species identification of Rhigonematomorpha nematodes remains mainly based on morphological features, with molecular-based identification still in its infancy. Also, current knowledge of the phylogeny of Rhigonematomorpha is far from comprehensive. Methods The morphology of Rhigonematomorpha nematodes belonging to the genus Rhigonema, collected from the millipede Spirobolus bungii Brandt (Diplopoda: Spirobolida) in China, was studied in detail using light and scanning electron microscopy. Five different genetic markers, including the nuclear small ribosomal subunit (18S), internal transcribed spacer (ITS) and large ribosomal subunit (28S) regions and the mitochondrial cox1 and cox2 genes of these Rhigonematomorpha nematodes collected from China and Rhigonema naylae collected from Japan were sequenced and analyzed using Bayesian inference (BI) and Assemble Species by Automatic Partitioning (ASAP) methods. Phylogenetic analyses that included the most comprehensive taxa sampling of Rhigonematomorpha to date were also performed based on the 18S + 28S genes using maximum likelihood (ML) and BI methods. Results The specimens of Rhigonema collected from S. bungii in China were identified as a new species, Rhigonema sinense n. sp. Striking variability in tail morphology was observed among individuals of R. sinense n. sp. ASAP analyses based on the 28S, ITS, cox1 and cox2 sequences supported the species partition of R. sinense n. sp. and R. naylae, but showed no evidence that the different morphotypes of R. sinense n. sp. represent distinct genetic lineages. BI analyses also indicated that R. sinense n. sp. represents a separated species from R. naylae based on the cox1 and cox2 genes, but showed that R. naylae nested in samples of R. sinense n. sp. based on the ITS and 28S data. Phylogenetic results showed that the representatives of Rhigonematomorpha formed two large clades. The monophyly of the families Carnoyidae and Ichthyocephalidae and the genus Rhigonema was rejected. The representatives of the family Ransomnematidae clustered together with the family Hethidae with strong support. Conclusions A new species of Rhigonematomorpha, R. sinense n. sp. is described based on morphological and molecular evidence. ASAP analyses using 28S, ITS, cox1 and cox2 data indicate the striking variability in tail morphology of R. sinense n. sp. as intraspecific variation, and also suggest that partial 28S, ITS, cox1 and cox2 markers are effective for molecular identification of Rhigonematomorpha nematodes. The phylogenetic results support the traditional classification of Rhigonematomorpha into the two superfamilies Rhigonematoidea and Ransomnematoidea, and indicate that the families Carnoyidae and Ichthyocephalidae and the genus Rhigonema are non-monophyletic. The present phylogeny strongly supports resurrection of the family Brumptaemiliidae, and also indicates that the family Ransomnematidae is sister to the family Hethidae. Graphical Abstract

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Section: Introductionmentioning

confidence: 99%

Molecular identification of a new species of Rhigonema (Nematoda: Rhigonematidae) and phylogenetic relationships within the infraorder Rhigonematomorpha

et al. 2022

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“…being mainly studied wild frogs obtained directly from their habitat, where several authors report the presence of gastrointestinal parasites in 100% of the animals examined (Cabral et al, 2011;Chen et al, 2021;Li et al, 2013;Sou et al, 2018). Being identified mainly parasites belonging to trematodes, acanthocephalans and cestodes, where the prevalence reported for each of the parasites found is variable due to the different environmental conditions, present in each study area (Bolek et al, 2003;Bolek & Janovy, 2007;Chen et al, 2021;Li et al, 2013;Sou et al, 2018). These results indicate that the overall prevalence of intestinal parasites found in our study is high and similar to the observed by other authors.…”

Section: Discussionmentioning

confidence: 99%

Gastrointestinal parasites in bullfrogs (Lithobates catesbeianus) in aquaculture production units in the Mexican central highlands

Hernández-Valdivia

Islas-Ojeda

Casillas-Peñuelas

et al. 2023

Rev. Bras. Parasitol. Vet.

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In Mexico, intensive production of bullfrogs is one of the most important aquaculture activities, due to growing demand for their meat. Frogs can be hosts for several parasites that negatively affect their development and health. The objective of this study was to identify the presence of intestinal parasites in bullfrogs in aquaculture production units. Eighteen bullfrogs aquaculture production units were selected, and 20 animals (n=360) from each farm. Fecal samples were obtained by mucosal scraping and processed using the concentration method. The overall prevalence of intestinal parasites was 70.5%, and all farms had frogs infected by some species of parasite. Two species of parasites were identified: Eimeria sp. and Strongyloides sp. Significant differences were found regarding parasite prevalence between males and females (73.8% vs 58.8%) and regarding tibia length (5.5 vs 6.1 cm) and weight (168 vs 187 g) between parasitized and non-parasitized frogs. In conclusion, the present study showed a high prevalence of intestinal parasites, and morphometric alterations (weight, snout-cloaca length, radio-ulna length, tibia length and distance between parotid glands) were identified in the parasitized animals. These results provided useful information that will enable establishment of adequate control measures to help minimize the adverse effects of these parasites.

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“…They can also facilitate adaptions in their host physiology, acting as a major force to promote their coevolution. Parasitic infections are highly prevalent in amphibians, but few systematic studies have been conducted on this topic [ 2 ] . The order Ascaridomorpha, a typical representative of large parasitic nematodes [ 3 ] , contains five families: Ascaridoidea, Cosmocercoidea, Heterakoidea, Seuratoidea and Subuluroidea.…”

Section: Introductionmentioning

confidence: 99%

The first genome assembly of the amphibian nematode parasite (Aplectana chamaeleonis)

Han

Liu

et al. 2023

Gigabyte

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Cosmocercoid nematodes are common parasites of the digestive tract of amphibians. Genomic resources are important for understanding the evolution of a species and the molecular mechanisms of parasite adaptation. So far, no genome resource of Cosmocercoid has been reported. In 2020, a massive Cosmocercoid infection was found in the small intestine of a toad, causing severe intestinal blockage. We morphologically identified this parasite as A. chamaeleonis. Here, we report the first A. chamaeleonis genome with a genome size of 1.04 Gb. The repeat content of this A. chamaeleonis genome is 72.45%, and the total length is 751 Mb. This resource is fundamental for understanding the evolution of Cosmocercoid and provides the molecular basis for Cosmocercoid infection and control.

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Morphology, genetic characterization and phylogeny of Aplectana dayaoshanensis n. sp. (Nematoda: Ascaridida) from frogs

Cited by 8 publications

References 22 publications

Molecular identification of a new species of Rhigonema (Nematoda: Rhigonematidae) and phylogenetic relationships within the infraorder Rhigonematomorpha

Molecular identification of a new species of Rhigonema (Nematoda: Rhigonematidae) and phylogenetic relationships within the infraorder Rhigonematomorpha

Gastrointestinal parasites in bullfrogs (Lithobates catesbeianus) in aquaculture production units in the Mexican central highlands

The first genome assembly of the amphibian nematode parasite (Aplectana chamaeleonis)

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