Cryptaphelenchus varicaudatus n. sp. (Rhabditida: Ektaphelenchinae) from Tehran Province, Iran.

Cryptaphelenchus varicaudatus n. sp. is described and illustrated. It was isolated from bark samples of dead or dying pine (Pinus spp.) trees with bark beetle frass and galleries, in Tehran province. The new species has 275- to 367-µm-long females (a medium-sized species) with distinctly annulated cuticle having three bands in lateral fields, lip region continuous with body contour, delicate knobbed stylet, monodelphic-prodelphic reproductive system with distinct spermatheca, short postvulval uterine sac (PUS), transverse vulval slit with raised posterior lip and body narrowing behind it, sclerotized vagina, simple intestine ending in a blind sac, having no rectum but vestigial anus in some specimens, and distal body end tip (tail tip) with variation in morphology (shape), from sharply or slightly pointed to bluntly rounded. Males of the new species are common, but less frequent than females, characterized by shorter body (235-278 µm long) compared to females, their posterior body end more ventrally bent, arcuate separate spicules with well-developed wide condyles, distinct rostrum having sharp, attenuated tip. The precloacal single supplement (P1) and the distally located pair of caudal papillae close to tail tip were only observed. The new species is morphologically compared with the species of the genus having short PUS and similar body end morphology. In molecular phylogenetic analyses using 1520- and 698-nt-long sequences of small subunit (SSU) and large subunit (LSU) rDNA D2/D3 fragments, the new species formed a clade with two currently available GenBank-derived, unspecified isolates/sequences in SSU and three other isolates/sequences in LSU trees, respectively.