[3] In 1946 he specialized in plant cytology at Sorbonne University and in 1948 he began working at the Station Internationale de Geobotanique Méditerranéenne et Alpine in Montpellier [fr], under the direction of Josias Braun-Blanquet, dedicating himself to the study of phytosociology.

[3] After winning a scholarship at the University of Kansas, where in 1952 he worked with the geographer A. W. Kuchler, he returned to Pavia and began to study the phytogeography of Mediterranean vegetation.

His research has influenced for years the activity of the Institute of Botany of the University of Pavia in the geobotanical and cartographic field: in Pavia he published the first map of the potential natural vegetation of Italy which, together with other notable studies in the phytosociological field, among which he won the presidency of the "Group of experts for the cartography of European vegetation of the Council of Europe".

[4] Together with Raffaele Ciferri, Tomaselli published 215 alternative names for the fungal component (the mycobiont) of lichens; most of these ended in the suffix -myces.

[5] Tomaselli died prematurely on 30 March 1982 in a road accident while returning from a work trip together with his colleagues Sebastiano Filipello and Mario Sacchi.