Gibbula beckeri
Gibbula beckeri | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Subclass: | Vetigastropoda |
Order: | Trochida |
Superfamily: | Trochoidea |
Family: | Trochidae |
Genus: | Gibbula |
Species: | G. beckeri
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Binomial name | |
Gibbula beckeri G.B. Sowerby III, 1901
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Gibbula beckeri is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.[1]
Description
[edit]The size of the shell attains 8 mm (0.31 in). The shell consists of the protoconch nucleus plus 4 whorls. The profile is rather strongly convex in the upper half of the whorl. There are spiral lirae 2 on 2nd and 3rd whorls, 3 on 4th whorl. These are broad and low, scarcely projecting above the profile, defined by impressed striae, the 3rd being peripheral and feebly carinate; an additional stria (or 2) between 1st and 2nd lirae, and 2-3 between 2nd and 3rd. Sometimes (as in a cotype) only 1 (midwhorl) lira on 2nd and 3rd whorls, but the peripheral one comes into view on 4th whorl. On the base of the shell there is usually a marginal lira and 7-8 weaker lirae, variable. The umbilicus is not completely closed in the largest shells. The growth lines are distinct.
The colour of the shell is grey or violaceous-grey with white or pale spots, radiating streaks, and/or zigzag marks. Very young shells (up to 2–3 mm (0.079–0.118 in) diameter) are uniformly violaceous. One specimen is yellowish with darker brown radiating patches forming a band below the suture, similar dark patches on the peripheral lira, between these two bands brown zigzags. Two specimens have red-brown radiating streaks on an emerald-green ground colour on 3rd and 4th whorls, streaks extending on to peripheral lira (cf. capensis). The base of the shell contains grey lirae, or is faintly streaked and spotted.[2]
Distribution
[edit]This species occurs in the Atlantic Ocean from Namibia to Port Alfred, South Africa
References
[edit]- Kilburn, R.N. & Rippey, E. (1982) Sea Shells of Southern Africa. Macmillan South Africa, Johannesburg, xi 249 pp. page(s): 40