Aspidogastrea

Aspidogastrea
Scientific classification
Kingdom:	Animalia
Phylum:	Platyhelminthes
Class:	Trematoda
Subclass:	Aspidogastrea
Families
See below.

See below.

The Aspidogastrea (Ancient Greek: ἀσπίς aspis “shield”, γαστήρ gaster “stomach/pouch”) is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and sister group to the Digenea. Species range in length from approximately one millimeter to several centimeters. They are parasites of freshwater and marine molluscs and vertebrates (cartilaginous and bony fishes and turtles). Maturation may occur in the mollusc or vertebrate host. None of the species has any economic importance, but the group is of very great interest to biologists because it has several characters which appear to be archaic.

Shared characteristics of the group are a large ventral disc with a large number of small alveoli ("suckerlets") or a row of suckers and a tegument with short protrusions, so-called "microtubercles".

Larvae of some species have ciliated patches. Those of Multicotyle purvisi have four patches on the anterior side of the posterior sucker and six at the posterior side, those of Cotylogaster occidentalis have an anterior ring of eight and a posterior ring of six, while larvae of Aspidogaster conchicola, Lobatostoma manteri, Rugogaster hydrolagi lack cilia altogether. Larvae of some species hatch from eggs, others do not.

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Wikipedia