A new species of the genus Acrobeles is described from natural areas in Tehran province, Iran. Acrobeles iranicus sp. n. is characterised by having a body 400-441 µm long in females, 'double' cuticle with rows of interannular punctations, lateral field with two incisures, labial probolae 9-12 µm long, pharyngeal corpus slightly fusiform and 2-4 times isthmus length, postuterine sac 5-15 µm or 0.2-0.5 times as long as body diam. and bearing larger cells in its proximal part and conical female tail (31-36 µm, c = 11.5-13.6, c = 2.3-2.9). In addition, Iranian populations of another three previously known species are studied: A. andalusicus, A. complexus and A. singulus, the third species having the male described for the first time. Descriptions, measurements and illustrations, including SEM photographs, are provided for all four species.

Three species of the family Panagrolaimidae are described from mainly natural areas in Tehran province, Iran and a new species of the genus Halicephalobus is described and a key to species identification provided. Halicephalobus persicus sp. n. is characterised by a body length of 204-246 µm long in females, lateral field with two incisures, lip region with six flat, slightly separated, lips, pharynx with swollen bulb-shaped metacorpus, pharyngeal corpus 2.5-2.6 times isthmus length, female tail subcylindrical with fine mucro (40-53 µm; c = 4.4-5.2; c = 6.9-12.3). Iranian populations of three other previously known species were studied, viz. Propanagrolaimus hygrophilus, Panagrolaimus dendroctoni and P. rigidus, all being reported from Iran for the first time. The species are described, measured and figured.