Coslenchus paramaritus n. sp. and C. cancellatus were identified based on morphological, morphometric, and molecular characteristics. The new species, C. paramaritus n. sp., is characterized by its cuticle with 18 longitudinal ridges excluding lateral lines, wide cuticular annuli (2.6-3.0 µm), a long tail (94-128 µm), the presence of males and the absence of sexual dimorphism in head shape. Molecular phylogenetic studies of the new species using D2-D3 expansion segments of 28S rRNA revealed that the new species formed a sister clade with three unknown populations of Coslenchus in Bayesian inference (BI) phylogeny, while C. cancellatus formed a sister clade with other Coslenchus species including C. oligogyrus, C. franklinae, C. costatus, C. turkeyensis and three unknown populations. C. cancellatus is recovered from Iran for the first time. [ABSTRACT FROM AUTHOR]