Two kinds of results (faunistics and biodiversity), obtained after the study of 7701 specimens belonging to 51 dipterous
families, are presented. The study was carried out in Navarra (Spain) in two kinds of forests (beech and mixed) with material collected by means of Malaise traps.
From the faunistic point of view, we highlight the following first records: a) 1 species new to Europe (Minettia quadrisetosa
(Becker), Lauxaniidae), b) 2 genera new to the Iberian Peninsula (Cerotelion Rondani, Keroplatidae and Pachycerina Macquart, Lauxaniidae), c) 1 genus new to Spain (Paraplatypeza Kessel & Maggioncalda, Platypezidae), d) 23 species new to the Iberian Peninsula, e) 6 species new to Spain, and f) 1 species new to mainland Spain.
From the biodiversity point of view, the most abundant families were the Lauxaniidae (36.46 %) and Heleomyzidae (23,32 %). Comparing the two forests, the Lauxaniidae (47.36 %) were the most abundant in the beech forest, whereas in the mixed forest the Heleomyzidae (29.91 %) were dominant. Finally, as regards to the species, of the 214 species identified, 154 (71.96 %) were collected in the beech forest and 182 (85.04 %) in the mixed forest. The two most abundant were Sapromyza basalis Zetterstedt (15.68 %) and Homoneura mediospinosa Merz (12.47 %), both in the family Lauxaniidae.