Ambigolimax is a genus of air-breathing land slugs in the family Limacidae, the keelback slugs.
There is still ongoing disagreement whether it is more appropriate to consider Ambigolimax as merely a subgenus of Lehmannia; the evidence for splitting them is phylogenetic trees constructed on the basis of DNA sequences.
Ambigolimax was constructed by Pollonera in 1887 to encompass A. valentianus and what he called A. fulvus but is now understood to be Malacolimax tenellus. He considered Ambigolimax as a subgenus of Agriolimax (now Deroceras) in the family Agriolimacidae. In 1926, Hesse transferred it to become a subgenus of Lehmannia in the family Limacidae. Since about 2007 the increasing tendency has been to split Lehmannia s.l. into two genera, Lehmannia s.s. and Ambigolimax. This splitting was based on the genetic evidence that the position of Malacolimax in the phylogenetic tree makes Lehmannia s.l. a paraphyletic group.
