Two Species of Free-Living Nematodes of the Genus <i>Daptonema</i> Cobb, 1920 (Nematoda, Monhysterida) New for Science from Artificial Reservoirs of Vietnam
An illustrated description of two new species of free-living nematodes of the genus <i>Daptonema</i>, <i>D. lutosum</i> sp. n. and <i>D. stagnalis</i> sp. n., found in artificial reservoirs for shrimp aquaculture in Vietnam is given. <i>D. lutosum</i> sp. n. is close to <i>D. borealis</i> Gagarin, 2020 and <i>D. dihystera</i> Gagarin, Nguyen Vu Thanh, 2005 in the structure of the spicular apparatus and body size. It differs from <i>D. borealis</i> Gagarin, 2020 by longer outer labial setae, posterior location of amphidial fovea from the anterior body end, shorter spicules and presence of posterior uterus in females; it differs from <i>D. dihystera</i> Gagarin, Nguyen Vu Thanh, 2005 by a shorter pharynx, longer outer labial setae, posterior location of amphidial fovea from the anterior body end and longer terminal setae at the tail tip. <i>D. stagnalis</i> sp. n. is the most similar to <i>D. dihystera</i> and <i>D. lutosum</i> sp. n. in the structure of the spicular apparatus and body size. It differs from both species in thicker body, more slender tail and absence of posterior uterus in females. The table of the main morphometric characters in males of the valid species from the ”swalbardensis” species group of <i>Daptonema</i> is presented.