''Steromphala nivosa'', common name the Maltese top shell, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
sea snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...
, a marine
gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Trochidae
The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...
, the top snails.
[MolluscaBase eds. (2020). MolluscaBase. Steromphala nivosa (A. Adams, 1853). Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=1039848 on 2020-12-30]
Description
The size of the shell varies between 6 mm and 9 mm. The umbilicate shell has an orbiculate-conoidal shape. It is gray with almost round spots. It is sulcate in a crosswise direction and longitudinally substriate. The
aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An opt ...
is almost round. The
columella is flexuous. The base of the shell is rounded.
Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
/ref>
Distribution
This species occurs in the Mediterranean Sea off Malta
Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...
.
References
Further reading
* Nordsieck F., 1982: ''Die europäischen Meeres-Gehäuseschnecken. 2. Auflage.'' * Gustav Fischer, Stuttgart; 539 pp., 38 pl.
* Smriglio C., Mariottini P. & Gravina F., 1991: ''Nota su alcune specie del genere Gibbula Risso, 1826 ex Leach ms''; Bollettino Malacologico 27 (5–9): 61–75
* Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213
External links
*
Adams A., 1851: ''An arrangement of Stomatellidae, including the characters of a new genus, and of several new species''; Proceedings of the Zoological Society of London 18: 29–40
Monterosato T. A. (di), 1888–1889: ''Molluschi del Porto di Palermo. Specie e varietà'' ; Bullettino della Società Malacologica Italiana, Pisa, 13 (1888[1889?
: 161–180 14 (1889): 75–81]
Affenzeller S., Haar N. & Steiner G. (2017). Revision of the genus complex Gibbula: an integrative approach to delineating the Eastern Mediterranean genera Gibbula Risso, 1826, Steromphala Gray, 1847, and Phorcus Risso, 1826 using DNA-barcoding and geometric morphometrics (Vetigastropoda, Trochoidea). Organisms Diversity & Evolution. 17(4): 789-812
{{DEFAULTSORT:Steromphala Nivosa
nivosa
Gastropods described in 1851