Ditylenchus behradi n. sp. (Tylenchomorpha: Anguinidae) from Iran, an integrative morphological and molecular study

A population of an unknown species of Ditylenchus was recovered from the rhizosphere of pistachio (Pistacia vera L.) in Gonabad county, Razavi Khorasan province, Iran. The new species, Ditylenchus behradi n. sp., is characterized by females with a body length of 801-932 µm, lateral fields with six incisures, a slender stylet 8.1-9.2 µm long, an elliptical median pharyngeal bulb with a distinct valve, the secretory-excretory pore located 95.8-108.7 µm from the anterior end, an elongated to pyriform basal pharyngeal bulb with a short overlap over the intestine, a relatively short post-vulval uterine sac (21.5-27.1 µm), and a tail 54.0-78.4 µm long with a bluntly rounded to occasionally pointed terminus. Males possess arcuate spicules 17.1-19.8 µm long. Morphological and morphometric comparisons demonstrated that the new species is most similar to Ditylenchus baoqingensis, Ditylenchus israelensis, Ditylenchus triformis, Ditylenchus valveus, and Ditylenchus zeae, but differs from these species by a unique combination of diagnostic characters. Molecular characterization was performed using partial sequences of the small subunit and the D2-D3 expansion segments of the large subunit ribosomal DNA, as well as the internal transcribed spacer region. Phylogenetic analyses using Bayesian inference consistently placed the new species within the group of Ditylenchus-like taxa, distinct from the recently established genera Ditylenchoides and Paraditylenchus, and supported its recognition as a new species. In all phylogenetic trees, D. behradi n. sp. formed an independent lineage closely related to D. israelensis and D. valveus. The present study expands the current knowledge of Ditylenchus diversity in Iran and further demonstrates the value of integrative taxonomy for species delimitation within Anguinidae.