The diversity of the Italian bee fauna was investigated over a four-year period at 52 sites in 8 Italian regions of Italy (Piedmont, Friuli-Venezia Giulia, Emilia-Romagna, Tuscany, Umbria, Molise, Sicily, and Sardinia). A previously agreed sampling methodology was used, and the bee collection protocol was based upon the transept method. The sampling sites were chosen within an agricultural landscape. An account on data processing concerning 8,674 captured specimens is presented. Over one third of the known Italian fauna, i. e. 355 species, were recorded. Three species, Hylaeus kahri Förster, 1871, Lasioglossum subaenescens (Pérez, 1896) and Osmia niveibarbis Pérez, 1902, are new records, and 45 species showed an enlarged distribution area. Seventyone percent of the bee species collected in the Italian agroecosystems and semi-natural landscapes are distributed in the Palearctic ecozone. The remaining 29% of the bee species are present in Europe: some species mostly occur in Central Europe, whereas others occur also in the Mediterranean countries. The 74.6% (total No. 265) of the 355 censused species was present in agroecosystems, and 81.4% (total No. 289) in semi-natural landscapes. The bee fauna composition varies along the North-South direction of the peninsula, with Halictidae being more abundant in Northern Italy and Anthophoridae more abundant in the South.
