Three new species of the genus Hopperia (Hematoda, Comesomatidae) from mangroves of the Mekong River Delta (Vietnam)

Three new species of free-living nematodes of the genus Hopperia (H. communis, H. dolichura, and H. mira) found in the Mekong River delta (Vietnam) are described and illustrated. Hopperia communis sp. n. is close to H. muscatensis Warwick 1973 but differs from it in the shorter body, longer tail, shorter spicules, another structure of cuticle areolation, and the absence of terminal setae on tail. H. dolichura sp. n. differs from H. muscatensis in the longer tail, shorter spicules, another form of spinneret, and the absence of terminal setae on tail. This species differs from H. communis sp. n. in the longer body and spicules and another structure of cuticle areolation. Hopperia mira sp. n. is close to H. muscatensis Warwick 1973 but differs in the shorter and thicker body, shorter spicules, another structure of cuticle areolation; vulva of the new species is situated farther from the anterior end of the body. A key to nine valid species of the genus Hopperia is given.