Resumen
Gammarus plays a central role in the detritus cycle and constitutes an important component in food webs. At the same time, taxonomy and morphological identification to species level is highly challenging in this genus. Thus, the freshwater gammarid diversity in the Caucasus biodiversity hotspot remains largely unstudied to date. We use DNA barcoding for the first time in assessing the biodiversity and taxonomy of gammarids within the amphipod genus Gammarus in the limnic ecosystems of Armenia. The results expand the knowledge on possible diversity and evolutionary lineages of Gammarus in the region. DNA barcodes obtained from our Armenian specimens consistently indicate four to six well-defined molecular operational taxonomic units (MOTUs) within three distinct morphospecies clusters. One to three MOTUs correspond to the Gammarus balcanicus species complex, two MOTUs to the G. komareki complex, and one MOTU to the G. lacustris complex. Five BINs out of six were unique and new to BOLD.