Gușuleac was born in Lucavăț, a village located west of the Duchy of Bukovina’s capital Cernăuți, where he attended high school from 1899 to 1907.
He specialized in marine biology at the zoological station in Trieste, and in systematic morphology and phytogeography at the universities of Vienna, Prague and Halle.
He headed the botanical institute and garden in Cernăuți, and was scientific inspector for Bukovina and Bessarabia.
He introduced complex methods of research in morphology and anatomy, systematics and experimental genetics.
Upon his recommendation, Bukovina's Ponoare flower fields, Todirescu plain and Slătioara old-growth forest were all declared natural reservations.