Geomonhystera longisoma sp. nov. and Mongolotheristus salolichini sp. nov. (Nematoda, Monhysterida) from Mekong River mouth, Vietnam
The paper provides illustrated descriptions of two new nematode species of the order Monhysterida Filipjev, 1929 found in the Mekong River Delta in Vietnam. Geomonhystera longisoma sp. nov. is morphologically similar to G. longispiculata Prado-Vera, Ferris, Subbotin, 2018 and G. chiautzingoensis Prado-Vera, Ferris, Subbotin, 2018. However, the new member of the genus has а thicker body, longer outer labial setae, and shorter spicules. Mongolotheristus tsalolichini sp. nov. is similar to M. altaicus Tsalolichin, 1985, but it has amphidial foveas located closer to the anterior body end, shorter dorsal apophysis of the gubernaculum, and papillae-shaped precloacal supplements (absent in M. altaicus ). The paper discusses the possibility of maintaining a separate status of the genus Mongolotheristus Tsalolichin, 1985, previously reduced to a synonym of the genus Daptonema Cobb, 1920.