New records of some rare mayflies (Insecta, Ephemeroptera) from Ukraine Author Martynov, Alexander V. text Ecologica Montenegrina 2018 2018-02-23 16 48 57 https://www.biotaxa.org/em/article/view/em.2018.16.6 journal article 54611 10.37828/em.2018.16.6 daad5c44-2db2-4e54-b6e2-89ba8a3937bb 2336-9744 8028193 Baetopus ( Raptobaetopus ) tenellus (Albarda, 1878) This transpalaearctic species is rare within all areal. Larvae are evidently predaceous ( Bauernfeind & Soldán 2012 ). One larva of B. tenellus ( Fig. 10 ) was registered in Styr River ( Figs 14, 15 ), the right tributary of the Prypyat’ River, at microhabitat with silted sand bottom and current velocity from 0.2 to 0.3 m /s. The additional parameters of waterbody in collecting place measured during the sampling were: water temperature 29°C, water hardness 259 ppm, pH 8.6. This is the first record of the genus Baetopus Keffermüller, 1960 , as well as the species B. tenellus within Ukraine . Material : 1 larva , Ukraine , Rivne Region , vicinity of Stara Rafalivka village , Styr River , 51.378866 , 25.863339 , h – 156 m a.s.l. , Martynov A. V . leg., 2.08.2017 – IN Riv 7 Btpten .