Lelenchus brevislitus n. sp. is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by having females with slender, 452-488 μm long, body lateral field vestigial as a plain simple band under scanning electron microscopy (SEM) in vulval region and absent in proximal and distal body ends, cephalic region short, ca 2 μm high, conical and truncate in anterior end in lateral view under SEM, dorso-ventrally flattened, amphidial pouches pocket-shaped and large under light microscopy (LM), their apertures short (ca 1 μm long in SEM) longitudinal sinuous slits remarkably wide near the small oral disc and significantly narrowing posteriad stylet, slender. 6.5-8.0 μm long, developed median bulb with distinct valvular plates, monodelphic-prodelphic reproductive system having a short post-vulval uterine sac (PUS), transverse vulval slit (V = 47.5-51.7) bearing small lateral membranes on each side, long filiform female tail (154-170 μm, c = 2.8-3.1, c′ = 21.5-28.3), and males unknown. The new species is considered to be a cryptic species inside the Tylenchidae. Morphological comparisons with all species of the genus are discussed. Phylogenetic studies were performed for further characterisation of the new species, and the results, using nearly full length 18S rDNA data, revealed it formed a clade with an isolate of L. leptosoma, both of which are in a sister clade with an isolate of Sakia. In a reconstructed phylogenetic tree using partial 28S rDNA sequences, the new species formed a monophyletic group, again with L. leptosoma, a sister clade to some Malenchus spp.

Malenchus geraerti n. sp., recovered from natural regions of northern Iran, is described and illustrated based on morphological, morphometric and molecular data. The new species is characterized by having females with a short body, an anteriorly wide S-shaped amphidial opening narrowing posteriorly, cuticle with prominent annuli, lateral field a plain band with smooth margins, muscular metacorpus with well-developed valve and corresponding plates, spermatheca filled with small spheroid sperm cells, vulva sunken in body with large epiptygma and no flap, and conical tail tapering gradually to a more or less pointed tip. Males of the new species are characterized by having a short body, tylenchoid spicules, adcloacal bursa with smooth margin and tail similar to that of the female. Morphologically, the new species is similar to five known species of the genus: M. fusiformis, M. machadoi, M. pachycephalus, M. solovjovae and M. undulatus. It most closely resembles M. pachycephalus, but as a cryptic species it can be differentiated using morphological and molecular characteristics. Comparisons with the four other aforementioned species are also discussed. Molecular phylogenetic studies using partial sequences of small and large subunit ribosomal DNA fragments reveal that the new species forms a clade with the species M. neosulcus in the small subunit (SSU) rDNA, and two species of Lelenchus in the large subunit (LSU) rDNA tree.

Molecular data on several species of trichodorids occurring in Iran are provided. Live specimens of two species, Trichodorus arasbaranensis and T. gilanensis, were collected from their type localities. One population of T. orientalis was collected from Arasbaran forests in Eastern Azarbayjan province. The species Paratrichodorus porosus, occurring in Gilan province, and one European isolate of P. pachydermus were also included in phylogenetic analysis. An Iranian population of T. minzi, representing only the second population found of this rare species, was recovered from soil samples collected from grasslands of north-western Iran and is in morphological congruence with the original description of the species. Besides morphological study, molecular phylogenetic study was performed on newly reported species using partial 28S rDNA data, and the phylogenetic relations of all sequenced species as inferred from Bayesian analysis are discussed. According to the phylogenetic tree, two newly described species, T. golestanensis and T. iranicus, formed a clade and further studies revealed they have the same morphology and molecular sequences of 28S rDNA D2-D3. Accordingly, T. golestanensis is regarded as a junior synonym of T. iranicus according to the Principle of Priority.