The Aspidogastrea (Ancient Greek: ἀσπίς aspis “shield”, γαστήρ gaster “stomach/pouch”) is a small group of flukes comprising about 80 species.

Aspidogastreans are an understudied class of parasitic flatworms that possess unique anterior attachment structures and are found exclusively in freshwater and marine environments, infecting a variety of hosts including fish, amphibians, and reptiles.

Aspidogastreans have a nervous system of extraordinary complexity, greater than that of related free-living forms, and a great number of sensory receptors of many different types.

[1][2][3] Their life cycle is much simpler than that of digenean trematodes, including a mollusc and a facultative or compulsory vertebrate host.

Adult worms live in the small intestine of the snubnosed dart, Trachinotus blochi (Teleostei, Carangidae), on the Great Barrier Reef.

If eaten by various prosobranch snails, larvae hatch in the stomach, and—depending on the species of snail—stay there or migrate to the digestive gland where they grow up to the preadult stage which has all the characteristics of the adult including a testis and ovary.

L. manteri extracted from fish could be kept alive for up to 13 days in dilute sea water in which they laid eggs containing larvae infective to snails.

Synapomorphies of the trematodes are presence of a Laurer's Canal, a posterior sucker (transformed to an adhesive disc in the Aspidogastrea), and life cycles involving molluscs and vertebrates.