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Diodora lineata (Family Fissurellidae)

Lined Diodora, Latticed Keyhole Limpet


The Lined Diodora ranges from southern Qld south through NSW, to Port Phillip Bay, Vic. (QLD, NSW, VIC)


The Lined Diodora is a distinctive keyhole limpet that is distinguished by its oval to rectangular shaped shell that is slightly narrower at the rear. It has a high apex with a round hole at the peak, just to the front of centre. The shells front slope is straight while its rear slope is convex. Its shell sculpture consists of 20 primary radial ribs and 2-3 minor ribs between. Oval concentric ridges cross these ribs and produce a distinctive latticed effect. It grows to a length of 40-55 mm. The shell margin is faintly crenulated or finely scalloped. The hole at the shell peak is for excurrent discharge and this takes away metabolic wastes. Because of its limpet-shaped shell there is no operculum. The porcellaneous shell is conical and limpet-like.

The shell exterior is coloured yellowish-white, blotched with brown, or it is marked with radial stripes. Inside the shell is white.

Ecology/Way of Life:

The Lined Diodora occurs under stones at low tide levels on sheltered to exposed rocky shores, down to 50 metres. It is a slow moving animal. Unlike other slit limpets, it can conceal itself under its shell. It grazes on algae and feeds on animal remains. It has a multi-toothed, brush-like radula tongue. Its distinctive shape and latticed pattern make identification easy.

Interaction with Humans/Threats:

The Lined Diodora has a restricted range limited mostly to NSW and only extending slightly into south-eastern Qld and including the eastern half of Victoria. Therefore, a widespread ecological disaster along the coast of NSW would be quite harmful to this species.

Other Comments:

Diodora lineata, Sowerby, 1835. Dio may come from the Greek word di, meaning twice, while dora may come from the Greek word Doris, a sea goddess. Lineata comes from the Latin word linea or linum, meaning line or lined. It is named Elegidion audax, Iredale, 1924, in Macpherson & Gabriel, 1962.

Further Reading:

Bennett, I. (1987). W. J. Dakin's classic study: Australian Seashores: a guide to the temperate shores for the beach-lover, the naturalist, the shore-fisherman and the student. p.274, Angus & Robertson.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.76, New Holland Press, Sydney.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.231, Reed.

Jansen, P. (2000), Seashells of South-East Australia. p.14, Capricornia Publications.

Macpherson, J. H. & Gabriel, C. J. (1962). Marine Molluscs of Victoria. p.44, Melbourne University Press. (Refer to this species as Elegidion audax).

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species. p.27, Museum of Victoria.

Wells, F. E. & Bryce, C. W. (1988). Seashells of Western Australia. Western Australian Museum.

Wilson, B. (1993) Australian Marine Shells. Prosobranch gastropods. v.I. p.52, Odyssey Publishing.

Wilson, B. R. & Gillett, K. (1979). A Field Guide to Australian Shells: Prosobranch Gastropods. p.30, Reed. (Refer to this species as Elegidion audax).


Text, map & photograph by Keith Davey.

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