Krynickillus

Identification

The main feature to distinguish the Krynickillus melanocephalus from other slugs is the distinct black head, antennae and neck, while the colour of the body can range from dirty blond to brown and bluish grey. Old individuals are darker than young ones. The back of the mantle, beginning behind the head, in the middle of the slug is usually light brownish, distinctively lighter than the rest of the body. The maximum length of the slug is 40-50 mm. There is a distinctive fingerprint pattern on the surface of the mantle in good light. The vent is located on the right side, at the back of the mantle. The back ridge, which starts at the tip of the end of the back and is sometimes quite weakly distinguished, is short (only 1/4 to 1/3 of the slug's length). The foot is uniformly white below. The mucus secreted by the slug is clear and colourless.

The natural species in Finland, ash-black slug (Limax cinereoniger) has, in addition to the more common dark specimen, also light grey or light brown color forms. It has a very strong, long and sharp ridge on its back, which extends about 2/3 forward from the tail tip. Instead, the ridge on the back of Krynickillus is weak and usually extends from the tail tip up to about 1/3 of the back length. In addition, the light-coloured ash-black slug usually has black or dark patterns on the back and sides. The ash-black slug also has underneath, in the sole, a longitudinal wide light stripe on a dark background.

Read more about identifying the Krynickillus from other slug species in the identification chart (in Finnish).