The genus Gobio in Italy was represented by the endemic species G. benacensis. The original distribution of this species was the Padano-Venetian district, but since a long time it was introduced in central Italy. Introductions of alien species to Italy during the last 10 years brought the sudden introduction of the Danubian G. gobio. Genetic and morphological analyses revealed the extensive presence of G. gobio, which rapidly colonised several rivers in Italy causing the progressive decline of G. benacensis, which now should be considered as an endangered species. Among examined populations those found in the Tagliamento River and transplanted in the Ombrone River represent genetic reservoirs of this species which will probably disappear in northern Italy.
Two new species belonging to the genus Willemia are described: W. bedosae sp. n. and W. christianseni sp. n. Redescriptions of Willemia dubia Christiansen & Bellinger, 1980 and W. similis Mills, 1934 are provided. Willemia vashtia Wray, 1950 is a new synonym of W. similis. These four species and four other of the genus constitute the Willemia anophthalma-group. This group is characterized by one feature not shared by the other species of the genus: the presence of setae a l on abdominal sternum IV. A comparative table and an identification key are given for these eight species, as well as some remarks on their habitats.