A new cave species of atyid shrimp of the genus Caridina H. Milne Edwards, 1837 was discovered during a survey of a subterranean habitat in southwestern Iran (Khuzestan Province, Tashan Cave). This is the first record of a cave atyid shrimp in Iran and the first documented occurrence of a Caridina species inhabiting sulphidic groundwater. Phylogenetic analyses and genetic distances support the status of Caridina tashanica sp. nov . as a distinct species, closely related to C. shahrazadae . Morphologically, the new species is characterised by reduced eyes and pigmentation, and by an extremely elongated rostrum with numerous teeth. Males have specific, triangular endopodite of pleopod I, and a rod-like appendix masculina of pleopod II with numerous long setae. Ovigerous females lay relatively large, oval, white eggs, which clearly indicate a landlocked life cycle. This study contributes to the knowledge of atyid shrimps in the Middle East and to the subterranean biodiversity of the sulphidic Tashan Cave ecosystem in Iran.