Costasiellidae
Costasiella cf. kuroshimae on Avrainvillea erecta. Locality: Lizard Island, Great Barrier Reef. The length of the slug is about 1 cm.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Infraclass:	Euthyneura
Superorder:	Sacoglossa
Superfamily:	Plakobranchoidea
Family:	Costasiellidae K. B. Clark, 1984
Species
See text

Costasiellidae is a taxonomic family of small to minute sacoglossan sea slugs. These are marine opisthobranch gastropod mollusks belonging to the superfamily Plakobranchoidea.^[1]

These sea slugs resembling nudibranchs, but are not closely related to them.

This family has no subfamilies.

The following genera belong to the family Costasiellidae:

• Costasiella Pruvot-Fol, 1951
• Panderevela Moro & Ortea, 2015