Elymus arasbarani sp. nov. (Poaceae; Triticeae), genus Elymus sect. Elytrigia from Arasbaran, northwest Iran

During a biosystematics study of the Iranian species of the genus Elymus in 2022–2024 a new species for the genus Elymus L. was found in the Arasbaran region of northwest Iran. The new species is morphologically close to Elymus repens and Elymus elongatiformis but differs in terms of inflorescence shape, shape and size of glumes, and characteristics of lemmas. The species is rhizomatous with long creeping rhizomes and grows alongside fields in wet places. A detailed taxonomic description of the new species; comparative analysis of allied species; and a key to close species, colored photographs, illustration, distribution map, ecological notes, and a maximum likelihood tree showing phylogenetic relationships of the new species with its related species are provided.