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Amphimonhystrella tropica sp. n. and Oncholaimus mekongis sp. n. (Nematoda) from the Mekong River, Vietnam

  • BIOLOGY, MORPHOLOGY, AND SYSTEMATICS OF HYDROBIONTS
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Abstract

Illustrated descriptions of two new free-living nematode species, Amphimonhystrella tropica sp. n. and Oncholaimus mekongis sp. n., found in the Mekong River delta (Vietnam) are given. A. tropica is similar to A. major Gagarin, Nguyen Dinh Tu, 2021 and A. paramonovi (Phan Ke Long, Nguyen Dinh Tu, Gagarin, 2020) in body size. It differs from first species in pharyngostoma shape, thicker body, longer tail and spicules, and by the absence of posterior uterus sac. It differs from second species in its thicker body, longer spicules, and different gubernaculum structure. Daptonema paramonovi Phan Ke Long, Nguyen Dinh Tu, Gagarin, 2020 is transferred to the genus Amphimonhystrella Timm, 1961: A. paramonovi (Phan Ke Long, Nguyen Dinh Tu, Gagarin, 2020) comb. nov. Dichotomy and pictorial keys for the identification of males of valid species of the genus Amphimonhystrella are given. Oncholaimus mekongis sp. n. is similar to O. balli (Kreis, 1934) and O. menzeli Schneider, 1973 in body size and spicule length. It differs from both species by the presence of big spiny seta in the precloaca area, the position of ventral papillae on tail in males, a thicker body, shorter outer labial setae, and a longer and more slender tail in males.

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ACKNOWLEDGMENTS

We are deeply grateful to our Vietnamese and Russian colleagues for help in conducting the field part of the study, as well as to the administration and staff of the Vietnam-Russia Tropical Center for the general organization of research in Vietnam.

Funding

This work was performed as part of the Ecolan E-3.4 research program of the Vietnam–Russia Tropical Research and Technological Center and State Task no. 121051100109-1.

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Authors and Affiliations

  1. Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Nekouzskii raion, Yaroslavl oblast, Russia

    V. G. Gagarin & V. A. Gusakov

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  1. V. G. Gagarin
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  2. V. A. Gusakov
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Correspondence to V. G. Gagarin.

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Conflict of interests. The authors declare that they have no conflicts of interest.

Statement on the welfare of animals. This article does not contain any studies involving animals or human participants performed by any of the authors.

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Translated by D. Martynova

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Gagarin, V.G., Gusakov, V.A. Amphimonhystrella tropica sp. n. and Oncholaimus mekongis sp. n. (Nematoda) from the Mekong River, Vietnam. Inland Water Biol 16, 174–184 (2023). https://doi.org/10.1134/S1995082923020050

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  • DOI: https://doi.org/10.1134/S1995082923020050

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