Trichodorus zanjanensis n. sp., collected from the rhizosphere of wild almond tree (Amygdalus scoparia Spach) in Zanjan Province, Iran, is described and illustrated based on morphological and molecular data. The new species is characterised by its body length (772-819 μm in males; 704-953 μm in females), and in having medium-sized onchiostyle (60-64 μm in males; 59-65 μm in females) and a short dorsal overlap of the intestine. Males of the new species have two ventromedian cervical papillae posterior to onchiostyle region, ventrally curved spicules, smooth, long and wide manubrium, gradually continuing in a narrower anterior part of the blade provided with bristles and marked from the wider and transversely striated main part of the blade, tapered towards distal end, three ventromedian precloacal supplements, the posterior one (SP1) situated at the level of anterior blade and gubernaculum situated at 24-25 μm from the cloaca. Females have one pair of sublateral body pores in the vulva region, medium rounded triangular to oval sclerotised vaginal pieces in lateral view, and pear-shaped vagina. The new species resembles T. persicus De Waele & Sturhan, 1987, T. minzi De Waele & Cohn, 1992 and T. taylori De Waele, Mancini, Roca & Lamberti, 1982. The results of morphological and morphometric comparisons and molecular data based on sequences of the partial 18S and D2-D3 expansion segments of 28S rRNA genes, clearly separated T. zanjanensis n. sp. from these known species and supported the description of T. zanjanensis n. sp. as a new species.

Two new species of Seinura are described and illustrated using both morphological and molecular characters. Seinura persica n. sp. is characterized by having females with a distinct cephalic region, stylet 19.5 (18-20) μm long, four incisures in the lateral fields, position of excretory pore anterior to the base of metacorpus, post-uterine sac 54.8 (50-60) μm long, and an elongate-conoid tail with a shallow depression on the dorsal side ending in a sharply pointed tip. Males have body length of 467 and 592 μm, spicules 15 and 16 μm long with a prominent triangular-shaped rostrum, developed condylus and no cucullus. Seinura hyrcania n. sp. is characterized by having an offset lip region, stylet 21.5 (18-24) μm long, three incisures in the lateral fields, excretory pore anterior to the base of the metacorpus, post-uterine sac 19 (12-25) μm long and conical tail ending in a filiform terminus. Morphological and morphometric diagnostic characters together with molecular data based on partial sequences of SSU and LSU of the ribosomal DNA gene are provided for these new species.

During a survey for nematodes associated with conifers in northern Iran, a known species of Laimaphelenchus was found in the bark samples of Taxus baccata L. trees and is described and illustrated here as L. deconincki Elmiligy & Geraert, 1972. It is characterized by lacking a distinct labial disc on the cephalic region; having six amalgamated labial sectors of equal width, separated by pairs of well-developed ribs; three lines in lateral field; the presence of a vulva flap; vagina surrounded by a cuticularised tube in which the walls vary in thickness; the post-uterine sac 25-62 µm long; tail with a single stalk-like terminus and four pedunculate tubercles; and absence of males. L. deconincki is morphologically very similar to L. cocuccii, but differs in the shape of the vaginal musculature (more angular vs round). Additional information on morphological characters and also the phylogenetic relationships of this known species using sequences of the D2/D3 region of the 28S ribosomal RNA gene is provided and added herein.

A new bisexual species of Rotylenchus from North-western Iran is described and illustrated based on morphological, morphometric and molecular studies. Rotylenchus urmiaensis n. sp. is characterised by having a truncate lip region with irregular longitudinal striation, lateral field areolated only in pharynx region, stylet length 34-40 μm, vulva positioned at 53-61%, and female tail conoid-rounded to dorsally convex-conoid with 5-10 annuli. Rotylenchus urmiaensis n. sp. appears to be similar to R. striaticeps, from which it may be differentiated morphologically by a slightly shorter body length (870-1269 vs 1000-1723 μm), shorter stylet (34-40 vs 39-50 μm), female tail shape (conoid-rounded to dorsally convex-conoid vs rounded), frequency of males (rare vs common as abundant as females), shorter spicules (39-43 vs 41-50 μm) and phasmid position (varying from three annuli anterior or three annuli posterior to anus vs at level to seven annuli anterior to anus), and molecularly. The results of phylogenetic analyses based on sequences of D2-D3 expansion region of 28S, ITS-rDNA, 18S rDNA, and the partial cytochrome c oxidase subunit 1 (coxI) mtDNA, confirmed the species differentiation and the close molecular relationship between R. urmiaensis n. sp. and R. striaticeps.

Two populations of the genera Trischistoma and Tripylella were recovered from the rhizosphere of grapevines and mosses growing on alder trees in Zanjan and Guilan provinces, respectively, Iran. The nematodes were identified as Trischistoma abharensis n. sp. and Tripylella intermedia, respectively. Trischistoma abharensis n. sp. is characterized by having females with body length 1069-1322 μm, presence of sparse somatic setae on the sublateral body, absence of ventromedian cervical setae, a distinct dorsal tooth directed anteriorly, absence of post-vulval uterine sac, and tail with one pair of subdorsal caudal setae. Males were not found. Tripylella intermedia is characterised by having females with body length 905-990 μm, annulated cuticle, stoma with two chambers: with dorsal tooth lying in posterior buccal chamber, and one large subventral and one small subventral tooth, respectively lying in posterior and anterior buccal chambers, cardiac glands large, composed of six fused cells, and tail 121-155 μm long, ventrally bent, anterior half broad, then suddenly narrowing, with posterior half tapered narrowly and cylindrically. The phylogenetic relationships of both species were analysed using sequences of the partial small subunit (SSU) and D2/D3 expansion segments of large subunit (partial LSU) of ribosomal RNA genes and are discussed.