Alvania minuta
| Alvania minuta | |
|---|---|
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| Shell of Alvania minuta (holotype) | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Superfamily: | Rissooidea |
| Family: | Rissoidae |
| Genus: | Alvania |
| Species: | †A. minuta
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| Binomial name | |
| †Alvania minuta (H. J. Finlay, 1924)
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| Synonyms | |
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Alvania minuta is an extinct species of minute sea snail, a marine gastropod mollusc or micromollusk in the family Rissoidae.[1]
Taxonomy
[edit]Alvania minuta (Golikov & Fedjakov, 1987) is a homonym and has become a synonym of Pusillina tumidula (G. O. Sars, 1878). [2]
Description
[edit]The length of the shell attains 1.5 mm, its diameter 0.9 mm.
(Original description) The minute shell is oval, clathrate and imperforate.
The protoconch consists of 2 globose glossy whorls. The nucleus is minute, rapidly enlarging.
The teleoconch contains about 2 whorls, indistinctly shouldered just below the suture, then flatly convex. The body whorl is bluntly angled, its base almost flat.
The axial sculpture commences first, consisting of strong bluntly-rounded ribs, sloping forwards and reaching from suture to suture, the interstices narrower; they number about 19, and cease just below line of suture on the body whorl. The axials are crossed by much weaker spirals, indistinct on early whorls, 4 on penultimate whorl, broad and flatly rounded (interstices sublinear) and cutting up axials into blunt laterally-elongate tubercles. A fifth spiral emerges from the suture-line on to base and is slightly crenulated by ends of axials. Below this are 2 smooth and much fainter ribs, the rest of base smooth.
The spire is a little higher than the aperture. The suture is much impressed. The aperture is slightly oblique, sub-ovate, angled above, effuse below. The peristome is discontinuous. The outer lip is thin, but does not appear to be finished. The arcuate columella is slightly oblique. [3]
Distribution
[edit]Fossils of this marine species were found in Tertiary strata in New Zealand
References
[edit]- ^ MolluscaBase eds. (2024). MolluscaBase. Alvania minuta (H. J. Finlay, 1924) †. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=832776 on 2024-02-14
- ^ MolluscaBase eds. (2024). MolluscaBase. Alvania minuta (A. N. Golikov & Fedjakov, 1987). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=141215 on 2024-02-14
- ^ Finlay H.J. (1924). New Zealand Tertiary rissoids. Transactions of the New Zealand Institute. 55: 480-494.
This article incorporates text from this source, which is in the public domain.
