First experience of a difficult genus. Adults are variable and males can often only be told apart by microscopic studies of their genitalia. Females are often indistinguishable. Somewhat easier in the Canary Islands as the genus consists of two allopatric species: P. coadunatus in Tenerife, and P. tibialis in more xeric conditions on Gran Canaria, Lanzarote, and Fuerteventura. (see www.entomologica.es/cont/publis/boletines/18.pdf ) These are tiny hoverflies but abundant and were the commonest species noted in Lanzarote during my stay.  Vernacular names  English: none yet Dansk: Klit-maskesvirreflue Deutsch:  Español: Français: Nederlands: Piemelkrieltje Norsk (bokmål): slank steppeblomsterflue Svenska: Slank stäppblomfluga