Austrocochlea diminuta
A small, variable-colored top snail endemic to Australian waters.
Austrocochlea diminuta is a marine gastropod mollusk belonging to the family Trochidae, commonly known as top snails. This small, solid shell reaches a height and diameter of 7 mm, with an ovate-turbinate shape and a dull, rough texture. The shell has five and a half whorls separated by impressed sutures. Its coloration is highly variable, ranging from solid maroon or slate to combinations with broad radiating buff stripes, or spiral bands articulated with buff against a maroon or slate background. The interior nacre of the aperture is bordered with emerald. The sculpture features elevated spiral ridges—four or five on the upper whorls and about sixteen on the last whorl—with smaller, closer ridges on the base. Both ridges and the spaces between them are crossed obliquely by fine growth striae. The aperture is subquadrate, brilliantly nacreous with a narrow border. The base of the columella is expanded externally and bears three small tubercles internally. The throat contains about seven entering ridges that begin at the bevel inside the lip, and the body whorl has a slight smear of callus. This species is endemic to Australia, found off the coasts of Northern Territory, Queensland, and Western Australia.
Quick Facts
- Taxon
- Austrocochlea diminuta
Facts from the source article.
Lore & Background
The original description by Charles Hedley notes the shell attains a height and diameter of 7 mm. It has an ovate-turbinate shape, is dull and rough, and contains 5½ whorls separated by impressed sutures. The color is very variable: entire maroon or entire slate, or with broad radiating stripes of buff, or the spirals articulated with buff on a maroon or slate ground, or combinations of these. The nacre of the interior of the aperture is bordered with emerald.
The sculpture includes elevated spiral ridges—four or five on the upper whorls, about sixteen on the last, and smaller and closer on the base. Both ridges and interstices are obliquely crossed by fine growth striae. The aperture is subquadrate, brilliantly nacreous with a narrow border. The base of the columella is externally expanded, internally bearing three small tubercles. The throat contains about seven entering ridges that commence at the bevel within the lip. The body whorl has a slight smear of callus.
This marine species is endemic to Australia and occurs off Northern Territory, Queensland, and Western Australia.
Reader's Guide
Austrocochlea diminuta is a species of sea snail in the family Trochidae, described by Charles Hedley. Its significance lies in its highly variable shell coloration and detailed sculpture, which includes elevated spiral ridges and fine growth striae. The shell's interior features a brilliantly nacreous aperture bordered with emerald, and the columella bears three small tubercles. The species is endemic to Australia, with records from Northern Territory, Queensland, and Western Australia. Its small size (7 mm in both height and diameter) and ovate-turbinate shape distinguish it among top snails. The original description provides a thorough account of its morphology, including the number of whorls, spiral ridges, and throat ridges. The species has been referenced in taxonomic works by Adams (1853) and Hedley (1913, 1918), and its genetic data are available through Barcode of Life and GenBank. As an endemic Australian marine snail, it contributes to the biodiversity of the region's gastropod fauna.
Did You Know?
- The shell height and diameter both attain 7 mm.
- The shell has 5½ whorls separated by impressed sutures.
- The base of the columella internally bears three small tubercles.
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