معرفی یک گونه جدید و پنج گونه شناخته شده از Tylencholaimellus Cobb in M.V. Cobb, 1915 (Dorylaimida: Tylencholaimellidae) از ایران

In a survay, 80 soil samples were collected from rhizosphere of different crops and orchards of Roodghat region, Sufiyan, East Azarbaijan province, Iran, during 2016-2017. The nematodes were extracted and fixed using common nematology techniques. The permanent microscopic slides were prepared and morphological and morphometric characters studied. Species identification was carried out based on available scientific literatur. As a result, five known and one new species of the genus Tylencholaimellus were identified among others. Tylencholaimellus sp. is distinguished by its 1.22-1.72 mm long body, dorylaimoid type cuticle, rounded and amalgameted lips, lip region offset by deep constriction, lacking oral disc, female genital system mono-opisthodelphic with long anterior uterine sac (55–103 μm), tail broadly rounded and short, males having one or two ventromedian supplements and bearing a hiatus. The new species comes close to T. persicus and T. polonicus. It differs from T. persicus by longer body length (1.22–1.72 vs 0.61–0.88 mm), shape of lip region (oral disc absent vs present), longer odontostyle (16-20 vs 12-14 μm), greater b (6-8.6 vs 4.1-4.9) and c (45-83 vs 32-38) values, lees c' (0.72-0.91 vs 1.1-1.3) and longer spicules (41-50 vs 22-25 μm). Compared to T. polonicus, the new species differs by longer body length (1.22–1.72 vs 0.85–1.31 mm), size and shape of lip region (10-13 μm wide, having a truncate stoma not swollen in the middle vs 13-15.5 μm wide, stoma a truncate cone slightly wider in its central portion), posteriorly located vulva (V = 34– 41 vs 23– 34), and longer spicules (41-50 vs 33-42 μm). The results of the phylogenetic analyses inferred from the partial sequences of the D2-D3 expansion regions of the 28S rDNA gene confirmed the species identity and indicated the phylogenetic position of Tylencholaimellus sp. and its relationships with closely related species or isolates. The new species D2-D3 sequences matched closely with the other Tylencholaimellus deposited in GenBank and forms a clade with them. Nblast results indicated the 85% similarity with T. persicus and 83% with Tylencholaimellus sp. In addition, Tylencholaimellus affinis, T. loofi, T. paracinctus, T. polonicus and T. striatus are reported for the first time from Iran that obtained in this study, too.