Sigmurethra Explained

Sigmurethra is a taxonomic category of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This is an informal group which includes most land snails and slugs.

The two strong synapomorphies of Sigmurethra are a long pedal gland placed beneath a membrane and retractile tentacles.^[1]

Several families in this group contain species of snails and slugs that create love darts.

Sigmurethra are known from the Cretaceous to the Recent periods.^[2]

Taxonomy

2005 Taxonomy

In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, Sigmurethra is an "Informal Group", a subsection of the Stylommatophora.^[3] It consists of the following families:

Superfamily Clausilioidea
- Family Clausiliidae
- † Family Anadromidae
- † Family Filholiidae
- † Family Palaeostoidae
Superfamily Orthalicoidea
- Family Orthalicidae
- Family Cerionidae
- Family Coelociontidae
- † Family Grangerellidae
- Family Megaspiridae
- Family Placostylidae
- Family Urocoptidae
Superfamily Achatinoidea
- Family Achatinidae
- Family Ferussaciidae
- Family Micractaeonidae
- Family Subulinidae
Superfamily Aillyoidea
- Family Aillyidae
Superfamily Testacelloidea
- Family Testacellidae
- Family Oleacinidae
- Family Spiraxidae
Superfamily Papillodermatoidea
- Family Papillodermatidae
Superfamily Streptaxoidea
- Family Streptaxidae
Superfamily Rhytidoidea
- Family Rhytididae
- Family Chlamydephoridae
- Family Haplotrematidae
- Family Scolodontidae
Superfamily Acavoidea
- Family Acavidae
- Family Caryodidae
- Family Dorcasiidae
- Family Macrocyclidae
- Family Megomphicidae
- Family Strophocheilidae
Superfamily Plectopyloidea
- Family Plectopylidae
- Family Corillidae
- Family Sculptariidae
Superfamily Punctoidea
- Family Punctidae
- † Family Anostomopsidae
- Family Charopidae
- Family Cystopeltidae
- Family Discidae
- Family Endodontidae
- Family Helicodiscidae
- Family Oreohelicidae
- Family Thyrophorellidae
Superfamily Sagdoidea
- Family Sagdidae

limacoid clade

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

Informal group Sigmurethra continued

Two superfamilies belongs to clade Sigmurethra, but they are not in the limacoid clade.

Superfamily Arionoidea
- Family Arionidae
- Family Anadenidae
- Family Ariolimacidae
- Family Binneyidae
- Family Oopeltidae
- Family Philomycidae
Superfamily Helicoidea
- Family Helicidae
- Family Bradybaenidae
- Family Camaenidae
- Family Cepolidae
- Family Cochlicellidae
- Family Elonidae
- Family Epiphragmophoridae
- Family Halolimnohelicidae
- Family Helicodontidae
- Family Helminthoglyptidae
- Family Humboldtianidae
- Family Hygromiidae
- Family Monadeniidae
- Family Pleurodontidae
- Family Polygyridae
- Family Sphincterochilidae
- Family Thysanophoridae
- Family Trissexodontidae
- Family Xanthonychidae

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

New families after 2005

Superfamily Streptaxoidea
- Diapheridae - In 2010, Sutcharit et al. (2010)^[4] established a new family Diapheridae within the Streptaxoidea.^[4]

2017 Taxonomy

After excluding groups not related, the informal group Sigmurethra becomes suborder Helicina, with the following nine infraorders and a collection of families with no superfamily：^[5]

Suborder Helicina ("Non-Achatinoid Clade")
- Infraorder Arionoidei
- Infraorder Clausilioidei
- Infraorder Helicoidei: formed from Helicoidea and Sagdoidea ^[6]
- Infraorder Limacoidei: formed from original limacoid clade
- Infraorder Oleacinoidei^[7]
  - Oleacinoidea

formed from original Testacelloidea but with the family Testacellidae excluded;

- - Haplotrematoidea

formed from original Rhytidoidea and Haplotrematidae^[8]

- Infraorder Orthalicoidei
- Infraorder Pupilloidei (Orthurethra)
- Infraorder Rhytidoidei: formed by Rhytidoidea merging with contents from Acavoidea.
- Infraorder Succineoidei (Elasmognatha)

Notes and References

Lunarejo. et al. 2008.
(in Czech) Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R.: Základy zoopaleontologie. - Olomouc, 1996. 264 pp., .
Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdés Á. & Warén A. 2005. Classification and nomenclator of gastropod families. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. . . 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278
Sutcharit C., Naggs F., Wade C. M., Fontanilla I. & Panha S. (2010). "The new family Diapheridae, a new species of Diaphera Albers from Thailand, and the position of the Diapheridae within a molecular phylogeny of the Streptaxoidea (Pulmonata: Stylommatophora)". Zoological Journal of the Linnean Society 160: 1-16. .
Bouchet. Philippe. Jean-Pierre Rocroi. Rocroi. Jean-Pierre. Hausdorf. Bernhard. Kaim. Andrzej. Kano. Yasunori. Nützel. Alexander. Parkhaev. Pavel. Schrödl. Michael. Strong. Ellen E.. 2017. Revised Classification, Nomenclator and Typification of Gastropod and Monoplacophoran Families. Malacologia. 1–2. 0076-2997. 1–526. 61. 10.4002/040.061.0201. 91051256. Philippe Bouchet.
2018 . Helicoidei . 1057261 . 2018-08-01 . MolluscaBase.
MolluscaBase . 2018 . Oleacinoidei . 1057260 . 2018-08-01.
MolluscaBase . 2018 . Haplotrematoidea H.B. Baker, 1925 . 994702 . 2018-08-01 .