Possibly A. harpae or A. angustatus. Also consider A. neglectus (Lilljeborg, 1900).
See Sinev, A. (2009). Discrimination between two sibling species of Acroperus (Baird, 1843) from the Palearctic (Cladocera: Anomopoda: Chydoridae). Zootaxa, 1-21. 10.5281/zenodo.189352. [View Online]
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