Reconstruction of Wiwaxia corrugata, copyright James St. John.

Belongs within: Metazoa.
Contains: Coleolidae, Sachitida, Stenothecoida, Monoplacophora, Cephalopoda, Gastropoda, Bivalvia, Helcionellida, Rostroconchia.

The Mollusca include such animals as clams, snails, squids and slugs. They often have a dorsal shell secreted by a mantle though this feature has been lost in numerous daughter lineages. The shell is primarily composed of aragonite with an outermost layer of protein (the periostracum). Molluscs generally have a ventral muscular foot for locomotion and a tooth-bearing radula for feeding, though again both characters may be lost or modified in various taxa.

Basal relationships between the various mollusc lineages have been subject to much debate, with a wide range of different arrangements suggested. One leading suggestion is a basal division between the Conchifera, which ancestrally possess a single shell (lost in some derived lineages, and divided into two valves in Bivalvia), and the Aculifera, which possess a body covering of spicules and may or may not have a shell composed of a series of separate valves. Alternatively, other authors have argued that the Aculifera are paraphyletic to the Conchifera. Relationships are, if anything, even more contentious within the Conchifera: almost every possible arrangement of the major subgroups has been proposed at one time or another. The name Pleistomollusca has been proposed for a clade supported by molecular data uniting the major classes Gastropoda and Bivalvia, but some recent analyses would also include the Scaphopoda (tusk shells) within this clade.

There are also a number of mostly Palaeozoic fossil groups of molluscs whose affinities remain obscure; many of these with simple, more or less cap-shaped shells have been classified in the past within a para- or polyphyletic taxon Monoplacophora. The soft-bodied Ediacaran fossil Kimberella quadrata has been proposed as a stem-group mollusc on the basis of associated traces that have been interpreted as signs of radular feeding.

See also: Tons of little tubes.

Mollusca (see below for synonymy)
    |--Kimberella Wade 1972 VP17, Gl79 (see below for synonymy)
    |    `--*K. quadrata (Glaessner & Wade 1966) [=*Kimberia quadrata] Gl79
    |--+--Odontogriphidae RE01
    |  |    |--Odontogriphus omalus Conway Morris 1976 VP17, RE01
    |  |    `--Bowengriphus Ritchie & Edgecombe 2001 RE01
    |  |         `--*B. perphlegis Ritchie & Edgecombe 2001 RE01
    |  `--Wiwaxiidae [Wiwaxidae] H62
    |       |--Wiwaxia Walcott 1911 VP17, Po08
    |       |    `--*W. corrugata (Matthew 1899) [=Orthotheca corrugata] H62
    |       `--Pollingeria Walcott 1911 H62
    |            `--*P. grandis Walcott 1911 H62
    `--+--Sachitida VP17
       `--Conchifera (see below for synonymy) VP17
            |  i. s.: Canopoconus EL11
            |         Stenothecoida R96
            |         Aeolidiopsis Pruvot-Fol 1956 [Aeolidiopsidae] BR17
            |         Archaeotremaria Yu 1979 (n. d.) [Archaeotremariidae, Archaeotremarioidea] BR17
            |           `--*A. polytremata Yu 1979 (n. d.) BR17
            |         Vitrella Clessin 1877 BR17
            |         Crossopoma Martens 1891 BR17
            |           `--*C. planorbulum (Lamarck 1816) (nom. cons) (see below for synonymy) BR17
            |         ‘Electra’ Albers 1850 non Lamouroux 1816 BR17
            |           `--*E. ceylanica (Pfeiffer 1845) [=Achatina ceylanica] BR17
            |         Granoconus Yu 1979 (n. d.) [Granoconidae] BR17
            |           `--*G. trematus Yu 1979 (n. d.) BR17
            |         *Xerosecta explanata (Müller 1774) BR17 [=Helix explanata BR17; incl. Carocolla albella G40]
            |         Peruinia Polinski 1922 [Peruiniinae, Peruiniini] BR17
            |           `--*P. peruana (Troschel 1847) [=Clausilia peruana] BR17
            |         Eucycloidea pulchella (d’Orbigny 1850) [=Purpurina pulchella] BR17
            |         Thoralispira laevis W01
            |         Kepinospira Yü 1963 RJ76
            |         Pseudotheca Redlich 1899 RJ76
            |         Siluracmaea Horny 1963 RJ76
            |         Sinkiangodiscus Yü 1963 RJ76
            |         Sinobellerophon Yü 1962 RJ76
            |         Sinosinuites Yü 1963 RJ76
            |         Decipula ovata Jeffreys in Friele 1875 [incl. Tellemya ovalis Sars 1878] N79
            |         Axinus N79
            |           |--A. croulinensis [incl. A. pusillus Sars 1868 (n. n.)] N79
            |           |--A. eumyarius Sars 1870 N79
            |           `--A. ferruginosus N79
            |         Artemis N79
            |           |--A. gigantea [=Cytherea (Artemis) gigantea; incl. A. ponderosa] C64
            |           `--A. lincta N79
            |         Syndosmya N79
            |           |--S. alba D56
            |           |--S. nitida N79
            |           |--S. ovata P75
            |           `--S. prismatica N79
            |         Cochlodesma praetenue N79
            |--Monoplacophora TRM20
            `--+--Cephalopoda TRM20
               `--Pleistomollusca [Archaeobranchia, Cyclomya, Helcionelliformes, Helcionelloida, Homomyaria] KC11
                    |--Gastropoda TRM20
                    `--+--Bivalvia TRM20
                       `--+--Helcionellida VP17
                          `--Rostroconchia TRM20

Mollusca incertae sedis:
  Eovasum D01
  Paraseraphs D01
  Succinodon (n. d.) N85
  Harmandia Rochebrune 1882 C92
  Deltoideum delta TP02
  Bilobissa dilatata TP02
  Umbella d’Orbigny 1841 E03
  Marcia plana W26
  Lapparia hebes A26
  Gilbertia tertiaria A26
  ‘Dimorpha’ Gray 1840 non Panzer 1806 C-S93
  Janella Grateloup 1838 BR05
  Lagena wiegmanni F66
  Ruma F66
    |--R. sebae F66
    `--R. umbilicata [incl. R. globosa] P79c
  Lampania zonalis F66
  Gladius fusus F66
  Macha strigillata F66
  Trigonella luzonica F66
  Cryptogramma flexuosa F66
  Tropicolpus albolapis M49
  Polinella lobata M49
  Zeacuminia pareoraensis M49
  Bartrumia tenuiplicata M49
  Zippora membranacea P75
  ‘Eatonia’ Smith 1875 non Hall 1857 S61
  Festilyria festiva (Lamarck 1811) ES88
  Somalipecten Waller 1986 ES88
    `--*S. cranmerorum Waller 1986 ES88
  ‘Margarita’ Lea 1836 nec Leach 1814 nec Leach 1819 LT64
  ‘Margarita’ Lea 1838 nec Leach 1914 nec Leach 1819 nec Lea 1836 LT64
  Transennella gerrardi Abbott 1958 B59
  Cypricardia J49
    |--C. californica [incl. C. duperryi, C. guinaiaca] C64
    `--C. corrugata Mighels 1844 J49
  Carditamera floridana Conrad 1838 [incl. Cypricardia nodulosa Mighels 1844] J49
  Cemoria princeps Mighels & Adams 1842 J49
  Badiotella Bittner 1890 M65
  Curvulites Rafinesque 1831 M65
  ‘Macquartia’ Roullier & Vorinsky 1848 non Robineau-Desvoidy 1830 M65
  Cadium Link 1807 LT61a
  Physodon integrum JB78
  Triton Linnaeus 1758 L58
    |--*T. littoreus Linnaeus 1758 L58
    |--T. lignarius C64
    |--T. nodifer PP64
    |--T. pilearis C64
    |--T. scaber C64
    `--T. vestitus C64
  Medusa Linnaeus 1758 L58
    |--M. aequorea Linnaeus 1758 L58
    |--M. aurita Linnaeus 1758 L58
    |--M. brachiata Linnaeus 1758 L58
    |--M. capillata Linnaeus 1758 L58
    |--M. cruciata Linnaeus 1758 L58
    |--M. marsupialis Linnaeus 1758 L58
    |--M. pelagica Linnaeus 1758 L58
    `--M. pilearis Linnaeus 1758 L58
  Eleuchus vulgaris Adams 1853 (n. d.) H08
  Irondalia Stinchcomb & Angeli 2002 TS11
  Bestashella Missarzhevsky in Missarzhevsky & Mambetov 1981 TS11
  Kistasella Missarzhevsky 1989 TS11
  Tianzhushanellidae [Siphonoconcha] WS93
    |--Tianzhushanella ovata Liu 1979 WS93
    `--Apistoconcha Pa08
         |--A. apheles Pa08
         |--A. presiphonalis Pa08
         `--A. siphonalis Conway Morris & Bengtson 1990 WS93
  Aroonia seposita Pa08
  Drillus maravignae PP64
  Myella bidentata PP64
  Sipho PP64
    |--S. terebralis (Gould 1860) [=Neptunea (Sipho) terebralis] C64
    `--S. torus PP64
  Scaeurgus unicirrus PP64
  Morio rugosa PP64
  Pleurobranchon meckeli PP64
  Compsomyax subdiaphana B56
  Rupertia Gray 1865 LT61b
  Williamsia Carus 1890 B61
  Lysechinus Gregory 1896 SG93, FP66
    `--*L. incongruens Gregory 1896 FP66
  Bukobia cockerelli PB27
  Tryonia clathrata PB27
  Carychiopsis schwageri E99
  Canalicia attracta E99
  Coleolidae MW04
  Deperetia Teppner 1921 G00
  Pecchiolia abyssicola N79
  Acteonia corrugata N79
  Colobocephalus costellatus N79
  Corbulomya N79
    |--C. maeotica PP64
    `--C. steenstrupii N79
  Magdala arctica N79
  Heterofusus balea N79
  Pomiatopsis P79a
    |--P. badgerensis P79a
    `--P. striatula P79a
  Birostra mccoyi Tennison Woods 1877 P79a
  Thalobia P79a
    |--T. dubia Tennison Woods 1877 P79a
    |--T. mariae Tennison Woods 1877 P79a
    `--T. tesselata Tennison Woods 1877 P79a
  Strophia uva Gi79a
  Cyclostomus Gi79b
    |--C. calcareus Gi79b
    |--C. kraussianus Gi79b
    `--C. zanguebaricus Gi79b
  Diplomphalus megei P79b
  Melantho W79
    |--M. decisa [incl. M. decisa var. melanostoma Currier in Walker 1879 (n. n.)] W79
    |--M. integra W79
    |--M. milesii W79
    |--M. obesa W79
    |--M. ponderosa W79
    `--M. rufa W79
  Stundella nasuta C64
  Gnathodon C64
    |--G. lecontei [incl. G. trigonum Petit 1853] C64
    `--G. mendicus (Gld. 1851) C64
  Byssoarca C64
    |--B. mutabilis C64
    `--B. pacifica C64
  Carinea emarginata C64
  Alora gouldii Ad. & Ad. 1856 [=Trichotropis gouldii] C64
  Levenia coarctata C64
  Rhizocheilus nux [incl. R. californicus, R. distans, Purpura osculans] C64
  Northia C64
    |--N. pristis C64
    `--N. serrata [=Buccinum serratum; incl. Nassa northiae] C64
  Clavella distorta C64
  Margaritiphora fimbriata [incl. Avicula barbata, A. cumingii, Margaritiphora mazatlanica] C64
  Oniscia tuberculosa C64
  Argina brevifrons C64
  Aricula libella C64
  Leiostraca C64
    |--L. iota [=Eulima iota] C64
    `--L. retexta C64
  Mumiola ovata C64
  Poronia rubra C64
  Strephona pedroana Conrad 1855 C64
  Aeneta harpa C64

Nomen nudum: Cemoria candida Mighels & Adams 1841 J49

Conchifera [Ancyropoda, Cephalaea, Cyrtonellea, Cyrtonellina, Cyrtosoma, Diasoma, Ganglioneura, Loboconcha, Perocepala, Rhacopoda, Tubicolae, Uberes, Visceroconcha] VP17

*Crossopoma planorbulum (Lamarck 1816) (nom. cons) [=Cyclostoma planorbulum, Cyclotus planorbulus, Cyclotus planorbutus (l. c.); incl. Crossopoma cornuvenatorium (Gmelin 1791)] BR17

Kimberella Wade 1972 VP17, Gl79 [=Kimberia Glaessner & Wade 1966 non Cotton & Woods 1935 Gl79; Kimberellidae, Kimberellomorpha]

Mollusca [Adenopoda, Amphineura, Archinacellida, Archinacellina, Branchifera, Coponautae, Cynostraca, Delocephala, Dermobranchea, Dipteronautae, Eumollusca, Exocephala, Glossophora, Halwaxiida, Hepagastralia, Isopleura, Monoconcha, Orthodonta, Phanerogama, Prosopocephala, Scutibranchiata, Serialia, Solenoconchia, Spiculata, Testaria, Univalvia]

*Type species of generic name indicated


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