گزارش سه گونه از خانواده(Nematoda, Dorylaimida) Nygolaimidae از نواحی جنگلی جنوب‌شرق خرم‌آباد، استان لرستان، ایران

During a survey on nematode fauna,120 soil samples were collected from the rhizosphere of trees in forest areas around Khorramabad county, Lorestsn province in 2022 and 2023 Nematodes were extracted using modified Whitehead tray method and after fixation, their morphological and molecular characteristics were studied using D2-D3 expansion domains of the LSU rDNA gene. Till now, only 11 species of the Nygolaimidae have been reported from Iran. In this study, three species belonging to the family, namely Aquatides christicki, Clavicaudoides clavicaudatus and Pravulvus hartingii were isolated and identified, among them A. christicki is the first record for Iran's nematode fauna. Additionally, in the molecular study, three sequences with the accession numbers of PP971542, PP971539 and PP971538 were obtained and the sequence of A. christicki is the first deposition in Gene Bank. This species can be characterized by having a cylindrical body, 1.45-1.99 µm long, ventrally curved into C-shape after fixation, tapering gradually toward anterior end, cuticle with 2.5- 3.5 µm thick at mid-body and 4.5- 5.5 µm on tail, lip region asymmetrical, with a slight ventral incline, amphidial fovea cup-shaped, aperture slit-like, 8.5 to 9.5 µm wide, or 42 to 44% of lip region wide, guiding ring simple and single, at a distance of 9.5 to 10.5 µm from anterior end, mural tooth linear, 19.0-21.5 µm long, 0.9 to one times of lip region wide, odontophore, 31-38 µm long or 1.6 to 1.7 times of tooth length, basal expanded part of pharynx 158-230 µm long and occupying about 49 to 52% of the pharynx length, nerve ring surrounding the anterior slender part of the pharynx at 130 to 175 µm from anterior end of body, three cardia glands ovoid, vulva a transverse slit, vagina 21.5 - 26.0 µm long or 42 to 46% of the body width, female reproductive system didelphic-amphidelphic, anterior and posterior genital branches length 196 - 231 and 186 to 277 µm, respectively, tail short and rounded, dorsally convex conoid. Compared the characters of the species to the original description, no significant difference was realized. Furthermore, C. clavicaudatus and P. hartingii fit in completely with their description in the literature. In the phylogenetic tree derived from this study, C. clavicaudatus was placed in the same clade with other species of this genus with high posterior probability (BPP=1) and the sequence of P. hartingi obtained in the present study along with other available sequence of the species form a well-supported clade with the highest posterior probability, too.