Land slug Laevicaulis alte (Veronicelloidea)
Sea slug Onchidella sp. (Onchidioidea)
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia

clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Systellommatophora


See text



The Systellommatophora (synonym Gymnomorpha) is a clade of primitive, air-breathing slugs, according to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005). They are marine and terrestrial pulmonate gastropods within the Heterobranchia. There are two superfamilies in this clade. Slugs in the superfamily Onchidioidea are primarily marine (except for five land-dwelling or freshwater species),[1] whereas slugs in the superfamily Veronicelloidea are primarily terrestrial.


No species in this clade have shells as adults.[1][2] These slugs are distinguished by the location of the anus at the rear of the body.[3]

Although neither superfamily bears shells as adults,[2] the Onchidioidea do possess a vestigial, 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):


  1. 1 2 Dayrat B. (2009). "Review of the current knowledge of the systematics of Onchidiidae (Mollusca: Gastropoda: Pulmonata) with a checklist of nominal species" (preview). Zootaxa. 2068: 1–26.
  2. 1 2 Schilthuizen M.; Thome J. W. (2008). "Valiguna flava (Heynemann, 1885) from Indonesia and Malaysia: Redescription and Comparison with Valiguna siamensis (Martens, 1867) (Gastropoda: Soleolifera: Veronicellidae)". Veliger. 50 (3): 163–170.
  3. Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 377. ISBN 0-03-056747-5.
  4. TILLIER, S (1983). "A new mountain Platevindex from Philippine Islands (Pulmonata: Onchidiidae)". Journal of Molluscan Studies. Malacological Soc London. 49 (supp12A): 198.
  5. Morton, Brian (1992). The Marine Flora and Fauna of Hong Kong and Southern China III___ Fouling and pollution, morphology, behavious and physiology, Hoi Ha Wan. Hong Kong University Press. ISBN 978-962-209-295-2.
  6. Dayrat, B.; Tillier, S. (2002). "Evolutionary relationships of euthyneuran gastropods (Mollusca): a cladistic re-evaluation of morphological characters". Zoological Journal of the Linnean Society. 135 (4): 403. doi:10.1046/j.1096-3642.2002.00018.x.
  7. "Systellommatophora". Integrated Taxonomic Information System.
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