Opisthobranchs is a now informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping.
Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
Euthyneura is a taxonomic infraclass of snails and slugs, which includes species exclusively from marine, aquatic and terrestrial gastropod mollusks in the clade Heterobranchia.
Lower Heterobranchia, also known as the Allogastropoda, is a group of rather specialized, highly evolved sea slugs and sea snails, within the subclass Heterobranchia.
Siphonaria pectinata, common name the striped false limpet, is a species of air-breathing sea snail or false limpet, a marine heterobranch gastropod mollusc in the family Siphonariidae.
Acochlidiacea, common name acochlidians, are a taxonomic clade of very unusual sea snails and sea and freshwater slugs, aquatic gastropod mollusks within the large clade Heterobranchia. Acochlidia is a variant spelling.
Umbraculoidea is a superfamily of unusual false limpets with a thin soft patelliform shell, marine gastropod molluscs in the clade Umbraculida, within the clade Euopisthobranchia.
Runcinoidea is a taxonomic superfamily or a clade Runcinaecea of sea slugs, marine gastropod mollusks in the order Runcinida
Acochlidiidae are a taxonomic family of shell-less freshwater gastropods, aquatic gastropod mollusks within the clade Acochlidiacea.
Hedylopsis is a genus of sea slugs, marine gastropod mollusks within the clade Acochlidiacea.
Tantulum elegans is a species of freshwater slug, an aquatic shell-less gastropod mollusk within the clade Acochlidiacea.
Strubellia paradoxa is a species of freshwater slug, a shell-less freshwater gastropod, an aquatic gastropod mollusk within the clade Acochlidiacea.
Pseudunela espiritusanta is a species of sea slug, an acochlidian, a shell-less marine gastropod mollusk in the family Pseudunelidae.
Acochlidium is a genus of freshwater slugs, an aquatic gastropod molluscs in the family Acochlidiidae.
Pseudunela is a genus of minute sea slugs, acochlidians, shell-less marine or temporary brackish or brackish gastropod mollusks in the clade Acochlidiacea.
Aiteng is a genus comprising three species of sea slug, A. ater and A. mysticus being found in intertidal zones while A. marefugitus is fully terrestrial. Aiteng is the only genus in the family Aitengidae. The generic name Aiteng is derived from the name of a black puppet Ai Theng, which is one of the shadow play puppets in southern Thailand.
Architectibranchia is a clade of marine snails, gastropod molluscs.
Pontohedyle is a genus of sea slugs, acochlidians, shell-less marine gastropod mollusks in the family Microhedylidae. Sea slugs in this genus are highly simplified and uniform.
Pseudunela viatoris is a species of sea slug, an acochlidian, a shell-less marine gastropod mollusk in the family Pseudunelidae.
Pseudunela marteli is a species of sea slug, an acochlidian, a shell-less marine gastropod mollusk in the family Pseudunelidae.
