A population of Deladenus, representing a new species, was recovered from Bonab’s Ghara-Gheshlagh lagoon. It is mainly characterized by having a long body (1051–1185 μm), long distance of anterior end to pharyngeal glands end (270–312 μm), six lines in lateral fields, and a short mucro-like differentiation on the tail tip. Furthermore, it has a small-sized stylet (8.5–11.0 μm) with three knobs, no postvulval uterine sac, and males with 24- to 28-μm-long tylenchoid spicules and penial tube. With six lateral lines, the new species is comparable with seven species of the genus: D. apopkaetus, D. brevis, D. cocophilus, D. durus, D. obtusicaudatus, D. processus, and D. ulani. It was furthermore compared with D. oryzae with an unknown number of lateral lines and D. aridus, D. obesus, and D. parvus having a different number of lateral lines but similar morphology. In the molecular phylogenic analyses using small and large subunit ribosomal DNA (SSU and LSU D2-D3 rDNA) sequences, the relationships of the new species with other species and genera were not resolved in SSU phylogeny. However, it formed a clade with Deladenus sp. and D. brevis in LSU phylogeny.
