Gammarus elifedae sp. nov., description of a new amphipod (Amphipoda: Gammaridae) species from Sarpunalınca Cave (Kastamonu, Türkiye), with an updated key for the Turkish freshwater Gammarus species

As a result of the increasing number of studies in recent years, strong evidence has emerged that the amphipod biodiversity in freshwater Türkiye is higher than previously thought. As a result of sampling in the Sarpunalınca Cave in Küre Mountains National Park in the north of Anatolia, Türkiye, a new amphipod species, Gammarus elifedae sp. nov., was described. The type locality, Sarpunalınca Cave, is a horizontal cave with 1683 m length. Although the newly described species was sampled from inside the cave, it has well-developed eyes, and its extremities are slightly elongated. Gammarus elifedae sp. nov., a typical Gammarus balcanicus-group species, has short setae on the posterior margins of its 3rd and 4th pereopods. Two male individuals were sampled, but no female individual was present. The holotype male has a body length of 18.5 mm and all extremities, including the mouthparts, are drawn and described in detail. Additionally, an identification key covering all species of the genus Gammarus identified from fresh waters of Türkiye (separately for pulex-, roeseli- and balcanicus- groups) is presented.