The head has a pair of sensory tentacles between the nostrils and the eyes, and this area of skin is white.

The body is black above and dark grey beneath, both with tiny white flecks.

[3] C. indistinctum is found in Paraguay, Uruguay, Brazil and Argentina at altitudes ranging up to 1,000 m (3,300 ft).

When on land, it mostly stays close to the river bank, but occasionally ventures some way from water.

Occasionally, it gets washed out to sea on mats of vegetation and has been found alive in the brackish water of estuaries.