Redescription of Laimydorus siddiqii Baqri & Jana, 1982 (Dorylaimida: Dorylaimidae) with its first molecular study.

A nematode population (SF7) belonging to the genus Laimydorus siddiqi, 1969, was isolated from the soils of sugarcane fields in the Haridwar district of Uttarakhand, India. Based on morphological, morphometrical, and molecular studies, the nematode was identified as Laimydorus siddiqii. This work represents the first molecular report of this species. Laimydorus siddiqui has a 2.6 to 3.08 mm long body, with a truncate lip region, linear odontostyle, double guiding ring, female genital system amphidelphic, longitudinal vulva, and females with a very long, filiform tail. Males have 56 - 63 μm long spicules and 28 - 29 ventromedial supplements. Molecular analyses utilizing segments of the 28S rDNA placed Laimydorus siddiqi in a clade with Laimydorus zehsaziani from Iran and other representatives of the genera Labronema, Dorylaimus, Prodorylaimus, Calcaridorylaimus, Mesodorylaimus, and Aporcelamellus. However, there is no available 18S rRNA sequence of any known species of Laimydorus, and our sequence is the first SSU rRNA of this genus. These molecular findings support the taxonomic positioning of Laimydorus siddiqui within the broader phylogenetic framework of the family Dorylaimidae, highlighting its relationships with closely related genera.