Lorica volvox, copyright Des Beechey.

Belongs within: Neoloricata.
Contains: Lepidochitonidae, Plaxiphoridae, Acanthochitona, Notoplax, Mopaliidae, Ischnochitonidae, Chitonidae, Chaetopleuridae, Callistochiton.

The Ischnochitonina are a group of chitons, including the greater number of living species, in which the ventral layer of the valves forms a well developed articulamentum (Smith 1960). The Cryptoconchidae, in which the dorsal tegmentum is reduced relative to the articulamentum, have been treated as their own separate suborder but appear to be phylogenetically nested within the Ischnochitonina. Members of the genus Callochiton have a fairly wide, leathery girdle covered with longitudinally packed minute narrow scales or spicules with only the tips showing (Smith 1960).

<==Ischnochitonina S60
|–Callochiton Gray 1847 GO06, S60 (see below for synonymy)
|    |–*C. laevis (Montagu 1803) [=Chiton laevis] S60
|    |–C. castaneus (Wood 1815) [=C. (Stereochiton) castaneus, C. (Trachyradsia) castaneus, Eudoxochiton castaneus] L70
|    |–C. chattonensis Ashby 1929 BE93
|    |–C. inornatus Ten.-Woods 1881 L70 (see below for synonymy)
|    `–C. septemvalvis GO06
`–+–Cryptoconchidae (see below for synonymy) P61
|    |–Acanthochitona GO06
|    |–Notoplax P61
|    |–Cryptoconchus Burrow 1815 P61 [=Cryptochoncus Clessin 1903 S60, Cryptoconctus Sowerby 1852 S60]
|    |    `–*C. porosus (Burrow 1815) [=Chiton porosus] P61
|    |–Choneplax Carpenter in Dall 1882 (see below for synonymy) S60
|    |    `–C. latus (Guilding 1829) (see below for synonymy) S60
|    |–Austrochiton Bergenhayn 1945 S60
|    |    `–*A. rostratus (Ashby & Torr 1901) [=Acanthochites rostratus] S60
|    |–Cryptoplax deBlainville 1818 (see below for synonymy) S60
|    |    |–*C. larvaeformis (Burrow 1815) [=Chiton larvaeformis] S60
|    |    |–C. burrowi (Smith 1884) [=Chiton burrowi] H09
|    |    |–C. japonica GO06
|    |    |–C. numicus S60
|    |    |–C. oculatus (Burrow 1815) BW09 [=Chiton oculatus H09]
|    |    `–C. pritchardi S60
|    `–Craspedochiton Shuttleworth 1853 P61 (see below for synonymy)
|         |–*C. laqueatus (Sowerby 1841) S60 [=Chiton laqueatus P61]
|         |–‘Pseudotonicia’ cuneata HS01
|         |–*Lophoplax’ finlayi Ashby 1926 F27
|         |–‘Notoplax (Amblyplax)’ foveauxensis Ashby 1926 (see below for synonymy) F27
|         |–‘Notoplax (*Amblyplax)’ oliveri Ashby 1926 [=Macandrellus oliveri Mestayer 1926] F27
|         `–C. rubiginosus (Hutton 1872) P61
`–+–+–+–Mopaliidae GO06
|  |  `–Cryptochiton Middendorff 1847 GO06, S60 [Cryptochitonidae]
|  |       `–*C. stelleri (Middendorff 1847) S60 (see below for synonymy)
|  `–Tonicella Carpenter 1873 GO06, S60 (see below for synonymy)
|       |–*T. marmorea (Fabricius 1780) S60 (see below for synonymy)
|       |–T. lineata (Wood 1815) [=Chiton lineatus, Lepidochitona (Tonicella) lineata] O27
|       |–T. rubra (Linnaeus 1767) [=Chiton ruber, Lepidochitona (Tonicella) ruber] O27
|       |–T. saccharina Dall 1878 [=Lepidochitona (Tonicella) saccharina] O27
|       |–T. sitkensis (Middendorff 1846) [=Chiton sitkensis, Lepidochitona (Tonicella) sitkensis] O27
|       `–T. submarmorea (Middendorff 1848) [=Lepidochitona (Tonicella) submarmorea] O27
`–+–+–Ischnochitonidae GO06
|  `–+–Chitonidae GO06
|     `–Lorica Adams & Adams 1852 GO06, P61 (see below for synonymy)
|          |–*L. cimolia (Reeve 1847) [=Chiton cimolius] S60
|          |–L. atkinsoni S60
|          |–L. cudmorei S60
|          |–L. duniana Hull 1910 F71
|          |–L. haurakiensis (Mestayer 1921) F27 [=Aulacochiton haurakiensis P61, *Zelorica haurakiensis F27]
|          |–‘Aulacochiton’ praecursor Smith et al. 1968 BE93
|          `–L. volvox (Reeve 1847) GO06, S60 [=Chiton volvox P61, *Aulacochiton volvox P61]
`–+–Chaetopleuridae GO06
`–Callistoplacidae [Callistochitonidae, Callistochitoninae, Callistoplacinae] SF77
|–Callistochiton GO06
|–Callistoplax Carpenter in Dall 1882 S60
|    `–*C. retusa (Sowerby 1832) [=Chiton retusus] S60
|–Ceratozona Dall 1882 (see below for synonymy) S60
|    `–C. rugosa (Sowerby 1841) S60 (see below for synonymy)
|–Middendorffia Carpenter in Dall 1882 (see below for synonymy) S60
|    |–*M. polii (Philippi 1836) [=Chiton polii; incl. C. cinereus Poli 1791 non Linné 1767] S60
|    `–M. caprearum PP64
`–Nuttallina Dall 1871 [=Nutallina (l. c.), Nuttalina (l. c.)] S60
|–N. fluxa (Carpenter 1864) (see below for synonymy) S60
|–N. californica (Reeve 1847) [=Chiton californicus] O27
`–N. thomasi Pilsbry 1898 O27

Ischnochitonina incertae sedis:
Subterenochiton Iredale & Hull 1924 [Subterenochitonidae] S60
`–*S. gabrieli (Hull 1912) [=Ischnochiton gabrieli] S60
Schizoplax Dall 1878 [Schizoplacidae] S60
|–*S. brandtii (Middendorff 1846) [=Chiton brandtii] S60
`–S. multicolor Dall 1920 O27
Lepidochitonidae S60
Schizochitonidae [Prochitonidae] S60
|–Schizochiton Gray 1847 S60
|    `–*S. incisus (Sowerby 1841) [=Chiton incisus] S60
`–Loricella Pilsbry 1893 [incl. Pseudoloricella Ashby 1925, Squamophora Nierstrasz 1905] S60
|–*L. angasi (Adams & Angas 1864) [=Lorica angasi] S60
`–L. sculpta S60
Plaxiphoridae S60

Cryptoconchidae [Acanthochitae, Acanthochitidae, Acanthochitinae, Acanthochitonidae, Acanthochitonina, Acanthochitoninae, Cryptoplacidae, Cryptoplacinae, Pseudotonicinae] P61

Callochiton Gray 1847 GO06, S60 [=Collochiton (l. c.) S60; incl. Acutoplax Cotton & Weeding 1939 S60, Eudoxoplax Iredale & May 1916 S60, Ocellochiton Ashby 1939 S60, Quaestiplax Iredale & Hull 1929 S60, Stereochiton Carpenter in Dall 1882 S60, Trachyradsia Carpenter in Dall 1878 S60; Callochitonidae, Callochitoninae]

Callochiton inornatus Ten.-Woods 1881 L70 [=Ca. (Trachyradsia) inornatus L70, Chiton inornatus F27, Eudoplax inornatus L70, Eudoxochiton (*Eudoxoplax) inornatus L70, F27; incl. Callochiton (Trachyradsia) lobatus L70]

Ceratozona Dall 1882 [incl. Ceratophorus Carpenter in Dall 1882 nec Schuckard 1837 nec Diesing 1850, Newcombia Carpenter in Dall 1882] S60

Ceratozona rugosa (Sowerby 1841) S60 [=Chiton rugosus S60; incl. Ch. guildingi Reeve 1847 S60, *Ceratozona guildingi S60, Ch. squalidus G79]

Choneplax Carpenter in Dall 1882 [=Chnoeplax (l. c.); incl. Chitoniscus Carpenter in Dall 1882 nec Herrmannsen 1852 nec Stål 1875] S60

Choneplax latus (Guilding 1829) [=Chitonellus latus; incl. Chiton strigatus Sowerby 1840, *Choneplax strigatus] S60

Craspedochiton Shuttleworth 1853 P61 [incl. Amblyplax Ashby 1926 S60, Angasia Carpenter in Dall 1882 S60, Augasia (l. c.) S60, Aristochiton Thiele 1909 S60, Bassethullia Pilsbry 1928 S60, Craspedoplax Iredale & Hull 1925 S60, Glyptelasma Iredale & Hull 1925 non Pilsbry 1907 S60, Ikedaella Taki & Taki 1929 S60, Leptoplax Carpenter in Dall 1882 S60, Loboplax Pilsbry 1893 S60, Lophoplax Ashby 1926 S60, Macandrellus Carpenter in Dall 1879 S60, Mecynoplax Thiele 1893 S60, Phacellopleura Carpenter in Dall 1879 non Agassiz 1846 S60, Phacellozona Pilsbry 1894 S60, Pseudotonicia Ashby 1928 S60, Spongiochiton Carpenter in Dall 1882 S60, Thaumastochiton Thiele 1909 S60]

*Cryptochiton stelleri (Middendorff 1847) S60 [=Chiton (*Cryptochiton) stelleri S60; incl. Ch. amiculatus Newcomb in Carpenter 1864 (n. n.) C64]

Cryptoplax deBlainville 1818 [=Crytoplax Gray 1821; incl. Ametrogephyrus Middendorff 1848, Chitonellus Lamarck 1819, Chitonella (l. c.), Chitoniscus Herrmannsen 1846, Dichachiton Middendorff 1848, Dibachiton (l. c.), Oscabrella Broderip 1835, Phaenochiton Middendorff 1848; Cryptoplacidae] S60

Lorica Adams & Adams 1852 GO06, P61 [incl. Aulacochiton Shuttleworth 1852 P61, Protolorica Ashby 1925 S60, Zelorica Finlay 1927 S60; Aulacochitonidae P61, Loricidae]

Middendorffia Carpenter in Dall 1882 [=Middendorfia; incl. Beanella Dall 1882, Beania Carpenter in Dall 1879 non Johnston 1840, Dawsonia Carpenter 1873 nec Brown 1811 (ICBN) nec Hartt in Dawson 1868 nec Nicholson 1873] S60

‘Notoplax (Amblyplax) foveauxensis Ashby 1926 [=Acanthochiton foveauxensis Mestayer 1926; incl. A. foveauxensis var. kirki Mestayer 1926] F27

Nuttallina fluxa (Carpenter 1864) [=Acanthopleura fluxa; incl. Chiton scaber Reeve 1847 non de Blainville 1825, *Nuttallina scabra] S60

Tonicella Carpenter 1873 GO06, S60 [=Toniciella (l. c.) S60; incl. Boreochiton Sars 1878 S60, Clathropleura Tiberi 1877 S60, Platysemus Middendorff 1847 S60]

*Tonicella marmorea (Fabricius 1780) S60 [=Chiton marmoreus S60, Boreochiton marmaoreus CS77, Lepidochitona (Tonicella) marmorea O27]

*Type species of generic name indicated


[BE93] Benton, M. J., & D. H. Erwin. 1993. Mollusca: Amphineura and ‘Monoplacophora’. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 125–130. Chapman & Hall: London.

[BW09] Bryce, C., & C. Whisson. 2009. The macromolluscs of Mermaid (Rowley Shoals), Scott and Seringapatam Reefs, Western Australia. Records of the Western Australian Museum Supplement 77: 177–208.

[C64] Carpenter, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Report of the British Association for the Advancement of Science 33: 517–686.

[CS77] Cramp, S., & K. E. L. Simmons (eds) 1977. Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palaearctic vol. 1. Ostrich to Ducks. Oxford University Press: Oxford.

[F27] Finlay, H. J. 1927. A further commentary on New Zealand molluscan systematics. Transactions and Proceedings of the New Zealand Institute 57: 320–485.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

[GO06] Giribet, G., A. Okusu, A. R. Lindgren, S. W. Huff, M. Schrödl & M. K. Nishiguchi. 2006. Evidence for a clade composed of molluscs with serially repeated structures: monoplacophorans are related to chitons. Proceedings of the National Academy of Sciences of the USA 103 (20): 7723–7728.

[G79] Guppy, R. J. L. 1879. First sketch of a marine invertebrate fauna of the Gulf of Paria and its neighbourhood. Part I.—Mollusca. Journal of Conchology 2: 151–172.

[HS01] Hayward, B. W., A. B. Stephenson, M. S. Morley, W. M. Blom, H. R. Grenfell, F. J. Brook, J. L. Riley, F. Thompson & J. J. Hayward. 2001. Marine biota of Parengarenga Harbour, Northland, New Zealand. Records of the Auckland Museum 37: 45–80.

[H09] Hedley, C. 1909. The Marine Fauna of Queensland: Address by the President of Section D. Australasian Association for the Advancement of Science: Brisbane.

[O27] Oldroyd, I. S. 1927. The Marine Shells of the West Coast of North America vol. 2 pt 3. Stanford University Press: Stanford University (California).

[P61] Powell, A. W. B. 1961. Shells of New Zealand: An illustrated handbook 4th ed. Whitcombe and Tombs Limited: Christchurch.

[S60] Smith, A. G. 1960. Amphineura. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I41–I76. Geological Society of America, and University of Kansas Press.

[SF77] Smith, A. G., & A. J. Ferreira. 1977. Chiton fauna of the Galápagos Islands. Veliger 20 (2): 82–97.

Last updated: 18 December 2021.

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