New Data on Species Diversity of the Genus Trichodorus Cobb, 1913 (diphtherophorina, Trichodoridae) in Iran, with Description of a New Species

Two populations of a new species of stubby root nematode, Trichodorus cadusiensis n. sp., were recovered from the rhizosphere of oak and plane trees in undisturbed natural forests of Gilan province, north Iran. The new species was illustrated and described based upon morphological and molecular characters. It is mainly characterized by having 592–949 μm long males having a 48–57 μm long onchiostyle, three ventromedian cervical papillae (CP) anterior to secretory-excretory pore (S-E pore), spicules ventrally curved, 34–48 μm long with a widened manubrium, an indented portion anterior to middle of spicules, with or without bristles, and widened blade. The females have a 715–887 μm long body, 49–57 μm long onchiostyle, S-E pore at about middle of narrow part of pharynx and triangular closely adjoining pars refringens vaginae pieces 3–4 μm wide with blunt tips. The new species was morphologically compared to those species of the genus having similarities in males in spicules shape/ornamentation and number of ventromedian cervical papillae, and in females in the shape of pars refringens vaginae pieces, or close phylogenetic relationships viz., T. andalusicus, T. asturanus, T. azorensis, T. beirensis, T. gilanensis, T. iranicus, T. lusitanicus, T. similis, T. velatus and T. viruliferus. In molecular phylogenetic analyses using maximal number of partial large subunit ribosomal DNA (LSU D2-D3) sequences of Trichodoridae, the included sequences of Trichodorus occupied three different placements. The new species formed a clade with T. similis and T. gilanensis in LSU tree with 0.85 Bayesian posterior probability (BPP).