Three Iranian populations of Discolaimium dubium are studied, including their morphological and morphometric characterization, molecular analysis (LSU-rDNA) and the description of the male for the first time. For comparative purposes, this species is distinguished by its 1.10 to 1.40mm long body, lip region offset by constriction and 8 to 10µm wide, odontostyle 7.5 to 10.5µm long with aperture occupying 59 to 76% of total length, neck 300 to 362µm, pharyngeal expansion 127 to 181µm long or 44 to 46% of the total neck length, uterus simple and 38 to 53µm or 1.2 to 1.5 times the body diameter long, V=52 to 58, tail conical (32-38µm, c=32-43, c′=1.6-2.0) with rounded tip and a hyaline portion occupying 14 to 15% of tail length, spicules 30 to 32µm long, and two or three widely space ventromedian supplements with hiatus. Both morphological and molecular data support its belonging to the genus Aporcella, whose monophyly is confirmed and to which the species is formally transferred as A. dubia (Das et al., 1969) comb. n.
