Morphological and molecular characterizations of Neodolichodorus bachlongviensis sp. n. (Nematoda: Dolichodoridae), a new plant-parasitic nematode species from Bach Long Vy island in Vietnam

Species of Neodolichodorus are plant-ectoparasitic nematodes, belonging to the family Dolichodoridae, occurring mainly in sandy soils. Fourteen species have been reported within this genus, each exhibiting unique morphological features aiding identification. In this study, we describe a new nematode species, Neodolichodorus bachlongviensis sp. n., which exhibits close morphological similarities to N. obtusus, N. adelaidensis, N. arelairius, and N. hainanensis in terms of lip region shape, tail shape, and stylet length. However, Neodolichodorus bachlongviensis sp. n. can be distinguished from each of these species based on specific morphological traits, including the position of the phasmid, separation of the labial region, body length, tail length, stylet length, cuticle annulation in the labial region, and the morphometric indices. Cluster and Multi-Dimensional Scaling (MDS) analyses also indicated that Neodolichodorus bachlongviensis sp. n. is insignificantly similar to other species of Neodolichodorus. Furthermore, molecular characterizations of Neodolichodorus bachlongviensis sp. n. based on the D2-D3 region of 28S rDNA and the COI mtDNA region have provided valuable insights into the genetic makeup and relationships of this newly discovered species. Remarkably, our study provides the first COI mtDNA sequences of the genus Neodolichodorus, facilitating future research on molecular aspect of this genus.