Alvania jeffreysi

Alvania jeffreysi
Shell of Alvania jeffreysi (specimen at the Smithsonian Institution)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Superfamily:	Rissooidea
Family:	Rissoidae
Genus:	Alvania
Species:	A. jeffreysi
Binomial name
Alvania jeffreysi (Waller, 1864)
Synonyms [1]
Onoba jeffrejsii [sic] (misspelling) Onoba jeffreysi(Waller, 1864) Rissoa jeffreysiE. Waller, 1864 (original combination)

Alvania jeffreysi is a species of minute sea snail, a marine gastropod mollusk or micromollusk in the family Rissoidae. ^[1]

Distribution

This marine species occurs off Southeast Greenland;off the Shetland Islands; in the Western Mediterranean Sea and in the White Sea, Russia.

Description

The length of the shell varies between 2.3 mm and 4 mm.

The species was described from a specimen found in sand dredged north of Unst, Shetland Islands, Scotland from a depth of 85 fathoms (155 m). It was named in honour of conchologist and malacologist John Gwyn Jeffreys.

(Original description) The white shell is conical, moderately strong, somewhat glossy and semi-transparent. It contains 5-6 whorls, sloping from the suture to the second ridge, and well rounded thence to the lower suture. The body whorl exceeds half the length of the shell, and is iquely rounded at the base.

Sculpture: on the penultimate whorl there are four slender but well-defined spiral ridges, the lower three of which arc stronger than the highest one, which is on the upper slope of the whorl. The ridges are crossed by about twenty-eight perpendicular ribs, not so much elevated nor nearly as strong as the ridges.They form with them square cancellations, the intersections of the ridges and ribs being scarcely raised, but slightly nodulous. The apical whorls are marked with spiral rows of close angular punctures. In each succeeding row the punctures lie below the ridges separating those of the preceding row. The base of the lowest whorl has 5-7 spiral ridges, for the most part uncrossed by the ribs, which generally terminate at the line of the upper part of the aperture.

The suture deeply defined and somewhat excavated. The aperture is roundish oval. The outer lip is smooth inside, and strengthened outside by a broad and strong rib. The inner lip is smooth and reflected on the columella, making the peristome continuous. The umbilical chink is very small. ^[2]

Habitat

Minimum recorded depth is 264 m. ^[3] Maximum recorded depth is 264 m. ^[3]

References

1. Alvania jeffreysi (Waller, 1864) . Gofas, S. (2009). Alvania jeffreysi (Waller, 1864). In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2009) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=141200 on 9 August 2010 .
2. Waller, E. (1864). "On a new British species of Rissoa". Annals and Magazine of Natural History . 3. 14 (80): 136–138. doi:10.1080/00222936408681672 . Retrieved 13 May 2016. This article incorporates text from this source, which is in the public domain .
3. Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". PLoS ONE 5(1): e8776. doi : 10.1371/journal.pone.0008776.

• Waller E. (1864). On a new British species of Rissoa. Annals and Magazine of Natural History. ser. 3, 14: 136-138
• Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca. in: Costello, M.J. et al. (eds), European Register of Marine Species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Patrimoines Naturels. 50: 180-213
• Gofas, S.; Warén A. (1982). Taxonomie de quelque espèces du genre Alvania (Mollusca, Gastropoda) des côtes ibériques et marocaines. Bollettino Malacologico. 18(1-4): 1-16
• "Alvania jeffreysi (Waller 1864 : Rissoa)". CLEMAM. Retrieved 13 May 2016.^{[ dead link ]}