Limacidae, also known by their common name the keelback slugs, are a taxonomic family of medium-sized to very large, air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the superfamily Limacoidea. The distribution of the family Limacidae is the western Palearctic. There are 28 species of Limacidae in Russia and adjacent countries. In this family, the number of haploid chromosomes lies between 21 and 25 and also lies between 31 and 35 (according to the values in this table). Zhiltsov & Schileyko (2002) elevated the subfamily Bielziinae to family level, Bielziidae, based on the morphology of the reproductive system of Bielzia coerulans. The following two subfamilies were recognized in the taxonomy of Bouchet & Rocroi (2005):