Redescription and revalidation of Plectonchus zondagi (Dale, 1967) Abolafia, Alizadeh & Khakvar, 2016 (Rhabditida, Brevibuccidae) from Iran with notes on taxonomic position of the genus

Summary Plectonchus zondagi is redescribed based on a population found in northern Iran. New morphological characterisations based on light and scanning electron microscopy are provided. Also, molecular analyses based on near full-length of small subunit and partial large subunit (SSU and LSU D2-D3) rDNA are provided. The recovered population of this species is characterised by having lips fused in pairs, amphidial openings posterior to frontal end, stoma with large cheilo-gymnostom, pharynx with scarcely swollen metacorpus, female reproductive system prodelphic, absence of post-vulval uterine sac, male with angular spicules and sigmoid gubernaculum and tail in both sexes conoid with acute tip bearing a refringent cuticular ring between the attached and detached parts of the tail cuticle. Phylogenetic analyses based on SSU and D2-D3 fragments of LSU rDNA showed that P. zondagi was nested within the family Brevibuccidae; however, additional sequences from valid species of the genus are required to confirm its classification within this family, as morphological data suggest.