Morphological and molecular characterisation of Aculonchus fumanensis sp. nov. (Nematoda, Dorylaimida, Leptonchidae) from Iran, with a revised taxonomy of the genus

Summary A new species of the rare leptonchid genus Aculonchus collected from two natural habitats of northern Iran, is characterised, including morphological description, morphometrics and molecular (18S, 28S rDNA) study. Aculonchus fumanensis sp. nov. is distinguished by its 0.64-0.92 mm long body, cuticle tylencholaimid and with abundant radial refractive elements, lip region cap-like, 9.5-10 μ m wide and offset by deep constriction, stylet 26-32 μ m long, odontophore bearing distinct basal flanges, neck 145-177 μ m long, pharyngeal basal bulb up to one-sixth of the total neck length and bearing a valvular chamber inside, female genital system di-ovarian with simple uterus and transverse vulva (V = 51-66), female tail conical and almost straight (25-34 μ m, c = 20-27, c′ = 1.5-2.1), and male unknown. The taxonomy of Aculonchus is revised, with an updated diagnosis, list of species, key to their identification, and a compendium of their main morphometrics. Besides, the evolutionary relationships of Aculonchus are briefly discussed.