Report of two species of the genera Acrobeloides Cobb, 1924 and Cephalobus Bastian, 1865 (Nematoda: Cephalobidae) from Semnan Province of Iran

Free living cephalobid nematodes are bacteriovorus and found in the most soils. During study of soil samples from Semnan Province two species of this group viz. Cephalobus persegnis Bastian, 1865 and Acrobeloides nanus (De Man, 1880) Anderson, 1968 were isolated and identified from rizosphere of weed and apricot, respectively. The first species lacks labial probolae, short lateral lips, short spermatheca and postuterine sac, tail cylindrical and in some population have mucro. In Acrobeloides nanus corpus fusiform and labial probolae acute. Both species have smooth cuticle, stoma comprising cheilostome, gymnostome and stegostome, spermatheca and postuterine sac are short. Description, measurements and drawings were provided for both species. Thisis the first record of these species from Semnan Province and second record from Iran. Males of C. persegnisare found for the first time from Iran and are described here in.