The long-tailed sea slug Stylocheilus longicauda was recorded for the first time from southwest coast of India. A single specimen measuring a total length of 70.51mm was collected from a floating bottle, along with bunch of goose-neck barnacles from Arabian sea off Narakkal, Vypeen Island, Kochi. Earlier identifications were made based on the morphology of the animal without resorting to description of radula. This makes it difficult to differentiate the species from Stylocheilus striatus which has similar characters. The present description details the external and radular morphology of Stylocheilus longicauda.

Mollusca, Opisthobranch, Aplysia, long-tailed sea slug.