Two new nematode species of the family Desmodoridae Filipjev, 1922, found in coral reefs in Vietnam, are described and illustrated. Onyx vulgaris sp. n. in body size and spicules length is close to D. disparamphis Tchesunov, Jeong, Lee, 2022 and O. orientalis Nguyen Dinh Tu et al., 2011. It differs from first species by the comparatively shorter and less slender tail, different form of terminal bulb of pharynx, different form of amphidial fovea and differs form of precloacal supplements in males. It differs from second species by the longer inner labial setae, shorter terminal bulb of pharynx, close to anterior body end located vulva and longer gubernaculum. Desmodora coralis sp. n. close to D. scaldensis de Man, 1889, D. macramphis S. Stekhoven, 1950 and D. nini (Inglis, 1963) in body size and absence of precloacal supplements in males and differs from all three species by the thinner body and presence of tubercle with pore on ventral side of tail in males.
Vietnam, coral reefs, free-living nematodes, new species
1. Gagarin V.G. An annotated checklist of free-living nematodes from mangrove thickets of Vietnam // Zootaxa. 2018. Vol. 4403, № 2. P. 261-288. DOI:https://doi.org/10.11646/zootaxa.4403.2.3
2. Gagarin V.G. Microlaimus capitatus sp. n. and Dichromadora simplex Timm, 1961 (Nematoda, Chromadorae) from the coast of Vietnam // Zootaxa. 2020. Vol. 4732, № 2. P. 323-331. DOI:https://doi.org/10.11646/zootaxa.4732.2.7
3. Inglis W.G. New marine nematodes from off the coast of South Africa. Bulletin of the British Museum (Natioanal History) // Zoology. 1963. Vol. 10, № 9. P. 529-552.
4. Man J.G. de. Especies de genres neuveaux de nematodes libres de la Mer du nord et de la Manche // Memoires de la Society Zoologique de France. 1889. T. 21. P. 1-10.
5. Nguyen Dinh Tu, Gagarin V.G. Free-living nematodes from mangrove forest in the Yen River Estuary (Vietnam) // Inland Water Biology. 2017. Vol. 10. P. 266-274. DOI:https://doi.org/10.1134/S1995082917030129
6. Nguyen Dinh Tu, Nic Smol, An Vangelsen, Nguyen Vu Thanh. Six new species of the genus Onyx Cobb, 1991 (Nematoda, Desmodorida) from coastal areas in Vietnam // Russian Journal of Nematology. 2011. Vol. 19. P. 1-20.
7. Nguyen Vu Thanh, Nguyen Thanh Hien, Gagarin V.G. Two new nematode species of the family Diplopeltidae Filipjev, 1918 (Nematoda, Araeolaimida) from coast of Vietnam // J. Biol. (Vietnam). 2012. Vol. 34, № 1. P. 1-5. DOI:https://doi.org/10.15625/0866-7160/v34n1.663
8. Platt H., Warwick R.N. Free-living marine nematodes. Part II. British Chromadorids / Synopses of the British Fauna (New series). New York. Kobenhavn, Koln: Brill Academic Pub. 1988. № 38. 502 p.
9. Schuurmans Stekhoven J.H. The free-living marina nemas of the Mediterranean: I. The Bay of Villefranche // Mem. Inst. Roy. Sci. natur. Belg. 1950. Vol. 37, № 2. P. 1-220.
10. Seinhorst J.V. A rapid method for the transfer of nematodes from fixative to anhydrous glycerin // Nematologica. 1959. Vol. 4. P. 67-69.
11. Tchesunov A.V., Nguyen Vu Thanh, Nguyen Dinh Tu. A review of the genus Litinium Cobb, 1920 (Nematoda, Enoplida, Oxystominidae) with descriptions of four new species from two constructing habitats // Zootaxa. 2014. Vol. 3872, № 1. P. 57-76. DOI:https://doi.org/10.11646/zootaxa.3872.1.5
12. Tchesunov A.V., Rachyuk Jeong, Wonchoel Lee. Onyx disparamphis sp. n. (Nematoda, Desmodorida) from South Korea with a taxonomic review of the genus // Peer. 2022. Vol. 10. P. 2-22. DOI:https://doi.org/10.7717/peerj.13010
13. Verschelde D., Gourbault N., Vincx M. Revision of Desmodora, with descriptions of new Desmodorids (Nematoda) from hydrothermal vents of the Pacific // Journal of the marine biological association of the United Kingdom. 1998. Vol. 78, № 1. P. 75-112.
