en Biology & physiology Biology & physiology پژوهشي Orginal research papers A new subterranean amphipod (<em>N. hegmatanensis</em> sp. nov.) belonging to the genus <em>Niphargus</em> Schi&ouml;dte, 1849 is described and illustrated. It was collected from Boghati spring in Hamedan Province, Iran. Materials are examined based on the morphological and molecular analyses. Molecular data derived from the nuclear gene 28S rDNA recovered relationships new species. <em>N. hegmatanensis </em>sp. nov. is placed within Iranian clade and phylogenetically has most similarity to <em>N. alisadri</em>. A relatively equal length of distal to proximal article in uropod III, equal size of rami in uropod I, trapezoid shape of propodi in both gnathopods and the short palpus that does not reach the tip of the outer lobe in maxilla I, are the major characteristics which serve to distinguish the new species from its congeners. Niphargus hegmatanensis sp. nov., Taxonomy, 28S rDNA, Boghati spring, Hamedan Province, Iran 1049 1063 http://jifro.ir/browse.php?a_code=A-10-3295-1&slc_lang=en&sid=1 S. Esmaeili-Rineh sesmaeili@razi.ac.ir 100319475328460041027 100319475328460041027 Yes Department of Biology, Faculty of Science, Razi University, Kermanshah S.A. Mirghaffari 100319475328460041028 100319475328460041028 No Department of Biology, Faculty of Science, Razi University, Kermanshah