One genus and two new for science nematoda species, found in coral reefs of coast area of Vietnam are described. Minisigma gen. nov. characterized by the finely annulated cuticle with lateral files in the form of two parallel sclerotized ridges. At both edges of lateral files there are cuticular pores. Pharyngostoma armed with large dorsal tooth and two small subventral teeth. The fovea of amphids in the form double-turn spirals. There are ocellius. Pharynx bulb elongate-oval, poorly expressed. In front of cloaca four S-shaped sclerotized supplements. Minisigma vietnamicum gen. nov., sp. n. is described and illustrated Hofmaenneria longisetosa sp. n. in body size is close to H. keoladensis Khan, Husain, Sultana, 2005 and H. niddensis Gerlach, Meyl, 1957. It differs from first species by relatively shorter pharynx, relatively shorter tail, longer outer labial setae. It differs from second species by thinner body, relatively shorter tail, longer outer labial setae and shorter spicules.
Vietnam, coral reefs, free-living nematodes, new species
1. Gagarin V.G., Nguen Din' Ty. Dva novyh dlya nauki vida svobodnozhivuschih nematod semeystva Desmodoridae Filipjev, 1922 (Nematoda, Desmodorida) s korallovyh rifov vo V'etname // Trudy Instituta biologii vnutrennih vod im. I.D. Papanina RAN, 2023. Vyp. 101(104). S. 39–48. DOI:https://doi.org/10.47021/0320-3557-2023-38-47.
2. Gagarin V.G., Nguen Din' Ty. Metachromadora (Bradylaimus) tenuis sp. n. i Spirinia laevioides Gerlach, 1963 (Nematoda, Desmodorida) s korallovyh rifov vo V'etname // Trudy Instituta biologii vnutrennih vod im. I.D. Papanina RAN, 2023. Vyp. 102(105), S. 25–35.
3. Gagarin V.G., Naumova T. V. Obzor roda Hofmaenneria Gerlach, Meyl, 1957 (Nematoda, Monhysterida) // Amurskiy zoologicheskiy zhurnal. 2022. T. 14. № 1. S. 131–138.
4. Cobb N.A. Contributions to a science of nematology, IX: one hundred new nemas. Baltimore. Waverly Press. 1920. P. 212–343.
5. Gagarin V.G. An annotated checklist of free-living nematodes from mangrove thickets of Vietnam // Zootaxa. 2018. Vol. 4403 (2). P. 261–288.
6. Gagarin V.G. Microlaimus capitatus sp. n. and Dichromadora simplex Timm, 1961 (Nematoda, Chromadorea) from the coast of Vietnam // Zootaxa. 2020. Vol. 4732. № 2. P. 323–331.
7. Gerlach S.A. Diagnosen never Nematodes aus der Kieler Bucht // Kieler Meeresforsch. 1956. Bd. 12. Heft. 1. S. 85–109.
8. Gerlach S.A., Meyl A.H. Freilebende Nematoden aus der Orhid–See // Beaufortia Series of Miscellaneous publications, zoological Museum of Amsterdam. 1957. Vol. 5, № 59. P. 157–170.
9. Khan R., Hussain A., Sultana R., Tahseen Q. Description of two monhysterida species (Nematoda) from Keoladeo National Park, Rajasthan, India // Nematology Mediterranean. 2005. Vol. 33. P. 67–73.
10. 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.
11. Nguyen Dinh Tu, Smol Nic, Vangelsen An, 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.
12. 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 // Journal of Biology (Hanoi). 2012. Vol. 34(1). P. 1–5.
13. Phan Ke Long, Nhuyen Nhi Thu, V.G. Gagarin, Nguyen Dinh Tu. Theristus coralis sp. n. and Thalassomonhystera gracilima sp. n. (Nematoda, Monhysterida) from coral reef off the coast of Vietnam // Amurskiy zool. zhurnal. 2023, Vol. XV. № 2. P. 401–410.
14. Seinhorst J.V. A rapid method for the transfer of nematodes from fixative to anhydrous glycerin // Nematologica. 1959. Vol. 4. P. 67–69.
15. Tchesunov A.V. Order Desmodorida de Coninck, 1965 // Handbook of Zoology. 2014. Vol. 2. P. 351–372.
16. Tchesunov A.V., Nguyen Vu Thanh, Nguyen Dinh Tu. A review of the genus Litinium Cobb, 1920 (Nematoda, Enoplida, Oxystomidae) with description of four new species from two constructing habitats. Zootaxa. 2014. Vol. 3872. № 1. P. 57–76.
