| Systellommatophora | |
|---|---|
| Laevicaulis alte (Veronicelloidea) | |
| Onchidella sp. (Onchidioidea) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| (unranked): | clade Heterobranchia clade Euthyneura |
| Families | |
|
See text. |
|
| Synonyms | |
|
Gymnomorpha |
|
The Systellommatophora (synonym Gymnomorpha) is a clade of primitive, air-breathing slugs according to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005). The Onchidioidea are primarily marine (except for five land-dwelling or freshwater species),[1] whereas the Veronicelloidea are primarily terrestrial.
These are marine and terrestrial pulmonate gastropods within the Heterobranchia.
No species have shells as adults.[1][2] They are distinguished by the location of the anus at the rear of the body[3].
Neither superfamily bears shells as adults,[2] although the Onchidioidea bear a vestigal, non-mineralized shell sac[4] and possess a larval shell.[5] It is not known whether or not the veronicellids bear a larval shell.[6]
According to the previous taxonomy of the Gastropoda (Ponder & Lindberg, 1997) Systellommatophora was considered to be a suborder or an order.[7]
The following two superfamilies and families have been recognized in the taxonomy of Bouchet & Rocroi (2005):