Gilvossius tyrrhenus (formerly Pestarella tyrrhena) is a species of mud shrimp which grows to a length of 70 mm (2.8 in).

It lives in burrows in shallow sandy parts of the sea-bed in the Mediterranean Sea and northern Atlantic Ocean.

[3] G. tyrrhenus is a small crustacean, up to 70 millimetres (2.8 in) long,[3] with a soft exoskeleton apart from two large, unequal claws.

Larval development is retarded by low salinities and aided by warmer temperatures, giving G. tyrrhenus a shorter reproductive season in the north of its range than in the south.

[9] G. tyrrhenus is parasitised by the isopod Ione thoracica and the barnacle Parthenopea subterranea.