Lower Heterobranchia, also known as the Allogastropoda, is a group of rather specialized, highly evolved sea slugs and sea snails, (marine gastropod mollusks) within the subclass Heterobranchia. Although the great majority of Lower Heterobranchs are indeed marine, a few have succeeded in making the transition to freshwater.

Description

The shell shapes in this group are typically those that are seen in the sundial, pyramid, rissoella and orbitestellid families of snails.

Taxonomy

2005 taxonomy

In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, the Lower Heterobranchia is an Informal Group. Superfamilies within the Lower Heterobranchia include: (Taxa that are exclusively fossil are indicated with a dagger †) For a more detailed taxonomy see: Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)

2010 taxonomy

Jörger et al. (2010) have redefined major groups within the Heterobranchia: they moved Glacidorboidea and Pyramidelloidea to Panpulmonata.

2014 taxonomy

Wägele et al. (2014): moved Rissoelloidea and Acteonoidea from Lower Heterobranchia to Euthyneura.

2016 taxonomy

Kano et al. (2016): moved Ringiculoidea from Lower Heterobranchia to Euthyneura. So the following taxa remain within the Lower Heterobranchia: