[5] The stem of Arion plus the suffix -unculus, which is a diminutive in Latin.

Pollonera[6] justifies why "Ariunculus" is appropriate rather than "Arionculus" (cf.

The subgenus name Ichnusarion is also based on "Arion", to which has been added "Ichnusa", a Latin name of Sardinia, where the single species of this subgenus is endemic.

Only two species are currently recognised:[7] subgenus Ariuncululus subgenus Ichnusarion Pollonera, 1890[6] Other species have been discounted as distinct members of the genus:[7] Genital characters that have been proposed as diagnostic of the genus are: At least in one species of Ariunculus, this last character reflects that sperm is transferred naked rather than in a spermatophore formed in the epiphallus; this is a fundamental contrast with Arion and Geomalacus.

[7] Ariunculus differs from Geomalacus, and is similar to Arion, in that the caudal gland is prominent and the mantle contains only calcareous granules rather than a shell plate.