A new member of the harpacticoid copepod family Tachidiidae Boeck, 1865 was found in sediment samples of meiobenthic harpacticoids taken during a study on the diversity of meiobenthic harpacticoids along the northern coast of the Persian Gulf. The taxonomic analysis of this material revealed that it contained an undescribed species. A new genus is herein proposed to accommodate the new species. The new genus, Pseudoneotachidius gen. nov., displays superficial similarities with Neotachidius Shen & Tai, 1963 and Cithadius Bowman, 1972, and a closer relationship is hypothesized with the former. The lack of a midventral copulatory pore, the female P5 endopodal lobe with two inner spines, and P1 with one inner seta on enp-3 are regarded here as synapomorphies for both Neothachidius and Pseudoneotachidius gen. nov. These two genera can be separated by several characters, including the structure and shape of the male fourth antennulary segment, segmentation of the antennary exopod, ornamentation of the male P2 enp-3, sexual dimorphism of the male P2 enp-2, structure and shape of the male P5, morphology of the male P2 and P3, male and female P5 armature complement and ornamentation, male P6, ventral spinulation pattern of the female genital-double somite, and in the mouthparts armature of amongst others. An updated key to the genera of the family Tachidiidae is presented.

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