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Family  Leptochitonidae

Leptochitonid chitons

The Leptochitonidae, previously known as Lepidopleuridae, is the least highly evolved family of the Polyplacophora, characterised by lacking insertion plates to secure the valves into the girdle. The valve surface is granulose and usually uncoloured. The girdle carries scales of various shapes as well as spicules or spines. In size, leptochitonids are generally small, up to 15 mm in length. They have a world-wide distribution, occurring from polar regions to the tropics and from the intertidal to abyssal depths. Intertidally, they are usually found under stones and in sediments.

There are only three species of this family known from NSW. Leptochiton badius is common and widely distributed. Parachiton puppis is uncommon and known mainly from the eastern shores of Sydney Harbour, while Leptochiton sperandus is known only from one specimen.

Family References:

• Iredale, T. & Basset Hull, A.F. 1927 Family Lepidopleuridae Pp. 41-48 in A Monograph of the Australian Loricates. Royal Zoological Society of New South Wales, Sydney. 168 pp. (This is a consolidated and repaginated version of the same material that had been published in sections in The Australian Zoologist over the years 1923-1927).

• Kaas, P. & Van Belle, R.A. 1985. Monograph of Living Chitons (Mollusca: Polyplacophora). Vol. 1. Order Neoloricata : Lepidopleurina. E.J. Brill / Dr. W. Backhuys Leiden 240 pp.

• Gowlett-Holmes, K. 1998. Family Lepidopleuridae. Pp. 178-179 in Beesley, P.L., Ross, G.J.B. & Wells, A. (eds) Mollusca: The Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing: Melbourne. Part B. viii 565-1234 pp.

• Gowlett-Holmes, K. 2001. Family Lepidopleuridae. Pp 71-75 in Wells, A. & Houston, W.W.K. (eds) Zoological catalogue of Australia. Vol. 17.2 Mollusca: Aplacophora, Polyplacophora, Scaphopoda, Cephalopoda. Melbourne: CSIRO Publishing, Australia.

Coverage

In addition to the two figured species, the following is recognised from NSW:

Leptochiton sperandus (Iredale & Hull, 1925)

Known only from the holotype, from off Ulldulla, NSW, in 70 fathoms (126 m). Length 4 mm.

Identification Notes

This family contains small chitons, up to 15 mm in length, with the surface unicoloured and ornamented with pustules in various configurations. The defining character is the absence of insertion plates on the valves.

See the introduction to Acanthochitonidae for an explanation of shell characters.