A new subterranean amphipod species from Western Anatolia (Türkiye): Niphargus hasansarii n. sp. (Amphipoda: Niphargidae)

A new amphipod species, Niphargus hasansarii n. sp., is described based on a single female specimen collected from Homeros Valley in İzmir Province, Western Türkiye. The species is distinguished by a unique combination of characters, specifically the high setation (≥4) along the outer margin of dactyli on both gnathopods, a single spine on the inner margin of the dactyli of pereopods 3–7, three distal setae on the inner lobe of maxilla I, a subrounded third epimeral plate, a single robust seta at the base of uropod I, and distinct facial and lateral spines on the telson lobes. Detailed morphological examination and illustrations of the holotype’s appendages were performed. The new species is compared with morphologically similar congeners, and diagnostic differences are highlighted. Although molecular data could not be obtained due to the specimen’s preservation conditions and absence of additional material, the combination of unique morphological features strongly supports the species’ distinct taxonomic status.