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Limacoid clade Temporal range: Cretaceous–Recent PreЄ Є O S D C P T J K Pg N
A live individual of Bielzia coerulans in the Limacidae
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Heterobranchia clade Euthyneura clade Panpulmonata clade Eupulmonata clade Stylommatophora clade Sigmurethra clade limacoid clade
Superfamilies
See text

The limacoid clade is a taxonomic clade of air-breathing land snails, semislugs and slugs, terrestrial pulmonate gastropod molluscs in the informal group Sigmurethra.^[1][2]

Distribution

The original ancestral area of limacoid families is thought to be the Palearctic region and south-eastern Asia.^[3]

Etymology

The word "limacoid" means "resembling a slug".^[4]

Typography of the name

In 1998, for the same taxon, Hausdorf^[2] used the name Limacoidea sensu lato.

The name of this taxon, the limacoid clade, was written by Bouchet & Rocroi (2005)^[1] with quotation marks like this: "limacoid clade".

Other typographical variants are used by various other authors, for example capitalizing and restricting the use of the quote marks thus: "Limacoid" clade and "Limacoid clade".

2003 taxonomy by Schileyko

The study of A. Schileyko in this group, published in parts 8-11 of his monograph between 2002 and 2003, did not discuss the system that Hausdorf had proposed.^[5] However, Schileyko refers to the work of Hausdorf, where this system was proposed,^[2] in part 10 (2003) on page 1390.^[5] So he was acquainted with this system before 2003.

Alternative taxonomy is as follows (subfamilies listed only for Helicarionidae and Zonitidae):

• Superfamily Helicarionoidea
  
  • Family Euconulidae
  
  
  • Family Trochomorphidae
  
  
  • Family Helicarionidae
    
    • Subfamily Geotrochinae
    
    
    • Subfamily Helicarioninae
    
    
    • Subfamily Papuarioninae
    
    
    • Subfamily Urocyclinae
    
    
  
  
  • Family Gymnarionidae
  
  
  • Family Rhysotinidae
  
  
  • Family Ariophantidae
  
  
  • Family Ostracolethidae
  
  
  • Family Ryssotidae
  
  
  • Family Milacidae
  
  


• Superfamily Dyakioidea
  
  • Family Dyakiidae
  
  
  • Family Staffordiidae
  
  


• Superfamily Gastrodontoidea
  
  • Family Gastrodontidae


• Superfamily Zonitoidea
  
  • Family Zonitidae
    
    • Subfamily Pristilomatinae
    
    
    • Subfamily Godwiniinae
    
    
    • Subfamily Zonitinae
    
    
    • Subfamily Oxychilinae
    
    
  
  
  • Family Daudebardiidae
  
  
  • Family Parmacellidae
  
  


• Superfamily Trigonochlamydoidea
  
  • Family Trigonochlamydidae


• Superfamily Vitrinoidea
  
  • Family Vitrinidae


• Superfamily Limacoidea
  
  • Family Limacidae
  
  
  • Family Agriolimacidae
  
  
  • Family Boettgerillidae
  
  

Moreover, after these groups, in the same infraorder Limacoinei, Schileyko listed six more superfamilies: Camaenoidea, Xanthonychoidea, Helicoidea, Polygyroidea, Hygromioidea and Arionoidea.^[5]

2005 taxonomy by Bouchet & Rocroi

Explanatory note

For this particular group of families, Bouchet & Rocroi adapted the taxonomic approach which was originally published by German malacologist Bernhard Hausdorf in 1998 in the Journal of Molluscan Studies.^[2]

Bouchet & Rocroi clearly state, on page 283:^[1]

However, in their paper, Bouchet & Rocroi (apparently accidentally) failed to show, graphically or typographically, any coverage of the limacoid clade in the taxonomic section of their paper, on pages 268-269.

Because of this omission, some authors have subsequently (mistakenly) included in the "limacoid clade" the two following superfamilies: Arionoidea and Helicoidea. This misunderstanding was copied by Poppe & Tagaro (2006)^[6] who attempted to explain the changes within this taxonomy to the public. This same error is reproduced in various other internet sources.

Taxonomic list

The taxonomy of Bouchet and Rocroi^[1] shows the "limacoid clade" as follows:

(Families that are exclusively fossil are indicated with a dagger †)

• Superfamily Staffordioidea
  
  • Family Staffordiidae
    


• Superfamily Dyakioidea
  
  • Family Dyakiidae
    


• Superfamily Gastrodontoidea
  
  • Family Gastrodontidae
    
  
  
  • Family Chronidae
    
  
  
  • Family Euconulidae
    
  
  
  • Family Oxychilidae
    
  
  
  • Family Pristilomatidae
    
  
  
  • Family Trochomorphidae
    
  
  
  • Fossil taxa probably belonging to the Gastrodontoidea
    
    • Subfamily † Archaeozonitinae
    
    
    • Subfamily † Grandipatulinae
    
    
    • Subfamily † Palaeoxestininae
    
    
  
  


• Superfamily Parmacelloidea
  
  • Family Parmacellidae
    
  
  
  • Family Milacidae
    
  
  
  • Family Trigonochlamydidae
    
  
  


• Superfamily Zonitoidea
  
  • Family Zonitidae
    


• Superfamily Helicarionoidea
  
  • Family Helicarionidae
    
  
  
  • Family Ariophantidae
    
  
  
  • Family Urocyclidae
    
  
  


• Superfamily Limacoidea
  
  • Family Limacidae
    
  
  
  • Family Agriolimacidae
    
  
  
  • Family Boettgerillidae
    
  
  
  • Family Vitrinidae
    
  
  

Cladogram

A cladogram showing phylogenic relations of families in the limacoid clade:^[3]

See also

As explained in the previous section, the superfamilies Arionoidea and Helicoidea do not belong to the limacoid clade. However, they are sometimes mistakenly included in this taxon.

References