Tree-ring or Etched Chiton

Onithochiton neglectus

Description 7

Medium 40 to 50mm long chiton. The plates are covered in an expanding pattern reminiscent of tree growth rings. In some individuals these might be darker green or browny-red patterns; often with wedge-shaped markings on the crest of the plates. The plates tend to be shiny and smooth and vary in colour from yellow to bright green. The skirt/girdle is wide and fleshy looking usually pink to pale green or even purplish. Some descriptions mention fine hairs on the skirt/girdle.

O. neglectus subantarcticus which has a distribution from the south of the South Island and sub-antartic islands also Chathams, has a wide pink skirt/girdle and green 'growth ring' patterned plates.

Distribtuion 7

Low intertidal zone, usually on the bottom of rocks. North Island, South Island, Stewart Island, Snares, and Chatham Islands.

Synonyms 7

Chiton undulatus (Quoy and Gaimard, 1835)
Icoplax chathamensis (Dell, 1960)
Onithochiton astrolabei (Rochebrune, 1881)
Onithochiton decipiens (Rochebrune, 1882)
Onithochiton filholi (Rochebrune, 1881)
Onithochiton marmoratus (Wissel, 1904)
Onithochiton neglectus neglectus (Rochebrune, 1881)
Onithochiton nodosus (Suter, 1907)
Onithochiton opiniosus (Iredale and Hull, 1932)
Onithochiton semisculptus (Pilsbry, 1893)
Onithochiton undulatus (G. B. Sowerby I, 1839)

References 7

New Zealand Mollusca, Marine Land and Freshwater Shells, A W B Powell, 1979

Sources and Credits

  1. (c) Tony Wills, some rights reserved (CC BY-NC), uploaded by Tony Wills
  2. (c) Lisa Bennett, some rights reserved (CC BY), uploaded by Lisa Bennett
  3. (c) WoRMS for SMEBD, some rights reserved (CC BY-NC-SA),
  4. (c) Femorale, some rights reserved (CC BY-NC),,%201881
  5. (c) tangatawhenua, some rights reserved (CC BY-NC), uploaded by tangatawhenua
  6. Tony Wills, no known copyright restrictions (public domain), uploaded by Tony Wills
  7. (c) Tony Wills, some rights reserved (CC BY-SA)

More Info

iNaturalist NZ Map

Depth intertidal
Places Chatham Islands, North Island, Snares, South Island, Stewart Island