Systellommatophora
Systellommatophora, also known as Gymnomorpha, is a small group of primitive air-breathing slugs in the gastropods. They live on land and in the sea and have no shells as adults. They are part of a larger group called Heterobranchia and are distinguished by having the anus located at the rear of the body.
Two main lineages (superfamilies)
- Onchidioidea: mostly marine slugs, with five species that live on land or in freshwater.
- Veronicelloidea: mostly land-dwelling slugs.
Shell notes
- Onchidioidea slugs have a vestigial, non-mineralized shell sac and a larval shell.
- It is unknown whether Veronicelloidea have a larval shell.
Taxonomy history
- In older classifications, Systellommatophora was considered a suborder or an order.
- In Bouchet & Rocroi (2005), they are recognized as two two main groups: Onchidioidea and Veronicelloidea.
This page was last edited on 2 February 2026, at 08:03 (CET).