EN
Ecdyonurus rizuni sp. nov. is described and illustrated from the Chornohora mountain-range of the Eastern Carpathians (Ukraine) (male imago and subimago, mature larvae and eggs). The new species belongs to the Ecdyonurus helveticus-group and is closely related to Ecdyonurus subalpinus Klapálek, 1907. Some data concerning its affinities, distribution and biology are discussed.