This type of slug abounds in my garden, located at 2,350 meters above sea level in the Andes of northern Peru (Chachapoyas, Amazonas department). Any idea to which family and genus it belong?
The pictures indicate the lack of dorsal keel, and a small shell could be missing at the rear end, which would indicate that it could belong to the Limacidae family and within this taxa it could belong to the Ambigolimax genus. It is difficult to determine from this pictures.
Here's a reference that should help: Thomé, J. W., S. R. Gomes and R. Souza Da Silva. 2001. Illustrierte und kommentierte Liste der Veronicellidae von Peru (Mollusca: Gastropoda). Archiv für Molluskenkunde 129: 69-75.