Akademik Veri Yönetim Sistemi
ZOOTAXA, cilt.1, sa.1, ss.0-1, 2025 (SCI-Expanded, Scopus)
The Kura-Aras River, one of the transboundary rivers of Turkey, is one of the important rivers of Transcaucasia. The two major tributaries of the river are named Kura and Aras. After passing through Turkiye, Georgia, Armenia, and Azerbaijan, they empty into the Caspian Sea. In the sampling study carried out in the upper basin of the Aras River in Turkiye, individuals belonging to the genus Gammarus were sampled. Morpho-genetic studies indicated that although the sampled individuals had morphological features similar to both Gammarus pulex and Gammarus balcanicus groups, they belonged to a new species: Gammarus arasensis sp. nov. Adult individuals belonging to the new species are medium-sized (holotype male, 12.5 mm) and robust, with kidney-shaped eyes. There is one long seta located anterodistally on the inner surfaces of the 1st to 4th coxa plates. There are no setae on the anterior edges of pereopods 5-7 and the epimeral plates are pointed. Morphologically, it is similar to Gammarus kischineffensis Schellenberg, 1937, which has been previously recorded in the region. The interspecific genetic distance analysis based on 28S ribosomal RNA and cytochrome c oxidase subunit I (COI) genes, the closest relative of Gammarus arasensis sp. nov is Gammarus kischineffensis, which showed a genetic distance of 16.23%, which is about three times greater than the lowest genetic distance observed for COI gene (5.24%), and a genetic distance of 1.44%, which is about thirteen times greater than the lowest genetic distance observed for 28S gene (0.11%). Phylogenies constructed by ML and BI exhibited largely similar topologies. The sister taxon of Gammarus arasensis sp. nov. is Gammarus kischineffensis. Gammarus arasensis sp. nov. was determined as a unique MOTU, distinct from other Gammarus, in the species delimitation analysis.