Diagnoses of all stages of the new genusAagaardiaare given. The genus includesA. sivertseni(Aagaard), originally described inEukiefferiella Thienemann, from Norway and Finland and described in all stages;A. protensasp.n. from Finland andA. triangulatasp.n. from Turkey described as male imagines; andA. longicalcissp.n. from Canada described in both sexes. The male imagines share bare eyes, strong punctation on wings, bare squama, extended costa, triangular gonostylus and two groups of extremely strong and sclerotized virga. The pupa and the female genitalia show relationship withParatrissocladiusZav[rcirc]el, while the larva is very similar to the larvae ofPsilometriocnemusSæther andPlatysmittiaSæther. Parsimony analyses suggest thatAagaardiaforms the plesiomorphic sister genus to the rest of theHeterotrissocladiusgroup combined.