RESUMEN
Specimens of 3 species of Neoechinorhynchus Stiles and Hassall, 1905, were collected from a number of species of marine fish along the Pacific coast of Vietnam. New information is added to the descriptions of Neoechinorhynchus (Neoechinorhynchus) longnucleatus Amin, Ha, and Ha, 2011, and its wider host and geographical distribution are reported. Similarly, more descriptive information and host and geographical records are added to our knowledge of Neoechinorhynchus (Hebosoma) manubrianus Amin, Ha, and Ha, 2011, and Neoechinorhynchus (Neoechinorhynchus) dimorphospinus Amin and Sey, 1996 . The latter species was previously known only from the Persian Gulf. The presence of the para-receptacle structure was documented in all 3 species of Neoechinorhynchus reported. The molecular characterization of N. dimorphospinus was carried out using a partial 18S rDNA sequence. The phylogenetic analysis showed that most species of Neoechinorhynchus are very closely related, while N. dimorphospinus was distinct from others in the tree. Metal analysis of hooks of N. dimorphospinus using Energy Dispersive X-ray Analysis also distinguished its characteristic finger print of high phosphorus and calcium and low sulfur levels.