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Taxon profile

species

Globose Violet-snail
Janthina exigua Lamarck, 1816

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  family Janthinidae - Purple Sea Snails »  genus Janthina

Scientific synonyms

Janthina vinsoni G. P. Deshayes, 1863

Images

Janthina exigua - Globose Violet-snail

Author: Macpherson & Gabriel

Janthina exigua - Globose Violet-snail

Author: Sowerby, G.B. (II)

Janthina exigua - Globose Violet-snail

Author: Powell, A.W.B.

Janthina exigua - Globose Violet-snail

Author: Fretter & Graham

Taxon in country check-lists*

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Description

Shell small, thin, fragile, colour violaceous with whitish band below the sutures, conically turbinate. Spire about half the length of shell. Whorls rounded, slightly obtusely angular about the middle. Sculptured with fine, somewhat irregular, oblique, radial striae. Interior light violet. Aperture somewhat ovate; outer lip very thin possessing a deep sharply angular sinus almost centrally situated; columella slightly reflected. Size: 0,5 inch.
Macpherson, J.H. & Gabriel, C.J., 1962. Marine Molluscs of Victoria.
Shell. In general like that of janthina but it has a taller spire, the whorls meeting slightly below the periphery of the upper one. The ornament is more marked, the growth lines elevated into distinct crests separated by deep grooves. On the last whorl they are V-shaped, changing direction from markedly prosocline to equally pronouncedly opisthocline at the periphery where there is often a shallow groove.
The protoconch is not so steeply tilted as in janthina and so is more exposed.
Aperture. Squarish. The outer lip arises from the peripheral groove of the last whorl and bears a deep V-shaped peripheral sinus. Its basal part is out-turned and curves sharply into the columella, the contact being nearly at right angles. The columella lies straight in the axis of the shell. The inner lip is thin and everted over a small umbilical groove.
Colour. A slightly darker violet than other species.
Size. Up to 17 x 14 mm. Last whorl = 80% of total shell height; aperture = 55-60% of shell height.
Animal, colour. As in janthina.
Fretter, V. and Graham, A., 1982. The prosobranch molluscs of Britain and Denmark. Part 7 - Heterogastropoda (Cerithiopcea, Triforacea, Epitoniacae, Eulimacea)

Interchangeable taxa

This is the smallest Violet Sea Snail in Victoria, easy to recognize by its radially sculptured whorls and deep angular sinus.
Macpherson, J.H. & Gabriel, C.J., 1962. Marine Molluscs of Victoria.
Author: Jan Delsing

Links and literature

EN Galli C.: WMSDB - Wolrdwide Mollusc Species Data Base July 10, 2013 [http://www.bagniliggia.it/WMSD/WMSDhome....] [as Janthina exigua Lamarck, 1816]
Data retrieved on: 23 November 2013
IT Repetto G., Orlando F. & Arduino G. (2005): Conchiglie del Mediterraneo, Amici del Museo "Federico Eusebio", Alba, Italy [as Janthina exigua Lamarck, 1816]

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