''Steromphala umbilicalis'',

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

the flat 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 ...

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 umbilicalis (da Costa, 1778). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=1039850 on 2020-12-30

Description

The size of an adult shell varies between 10 mm and 22 mm. The shell is more depressed than ''

Gibbula cineraria ''Steromphala cineraria'' is a species of small sea snail, a marine gastropod mollusc in the family Trochidae, the top snails.MolluscaBase eds. (2020). MolluscaBase. Steromphala cineraria (Linnaeus, 1758). Accessed through: World Register of ...

'', and (although the base is flatter) never inclined to a pyramidal form. The spiral ridges are sharper and fewer, especially in the young. The coloring is different; both have a similar kind of marking, but in the present species the longitudinal rays or streaks are red, besides being broader and not half so many as in the other species. They are sometimes zigzag, instead of being broken into spots or interrupted by the

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

. This species is striped, the other lineated. Just within the outer lip are two borders, one of yellow, the other of green variegated by red spots. This edging is minutely tubercled like shagreen.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
/ref>

Distribution

This marine species occurs in European waters and in the Mediterranean Sea off

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

. It is found from the upper shore into the sublittoral on sheltered rocky shores and is tolerant of emersion and

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

waters.

References

* Backeljau, T. (1986). ''Lijst van de recente mariene mollusken van België ist of the recent marine molluscs of Belgium'' Koninklijk Belgisch Instituut voor Natuurwetenschappen: Brussels, Belgium. 106 pp. * 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 * Muller, Y. (2004). ''Faune et flore du littoral du Nord, du Pas-de-Calais et de la Belgique: inventaire. oastal fauna and flora of the Nord, Pas-de-Calais and Belgium: inventory'' Commission Régionale de Biologie Région Nord Pas-de-Calais: France. 307 pp

External links

*
Da Costa E. M., 1778: ''Historia Naturalis Testaceorum Britanniae''; London: Millan, White, Elmsley & Robson XII + 254 + VIII p., 17 pl

Montagu G., 1803: ''Testacea Britannica, or natural history of British shells, marine, land and the fresh-water, including the most minute: systematically arranged and embellished with figures''; Romsey. London pp. XXXVII + 606 + 16 pl.

J.F. (1791). Vermes. In: Gmelin J.F. (Ed.) Caroli a Linnaei Systema Naturae per Regna Tria Naturae, Ed. 13. Tome 1(6). G.E. Beer, Lipsiae [Leipzig
pp. 3021-3910">eipzig">J.F. (1791). Vermes. In: Gmelin J.F. (Ed.) Caroli a Linnaei Systema Naturae per Regna Tria Naturae, Ed. 13. Tome 1(6). G.E. Beer, Lipsiae [Leipzig
pp. 3021-3910//www.biodiversitylibrary.org/item/83098#5]
Norman A. M., 1888: ''Museum Normanianum, or a catalogue of the Invertebrata of Europe, and the Arctic North Atlantic Oceans. IV Mollusca marina. V. Brachiopoda''; Durham pp. 30

Jeffreys J. G., 1862-1869: ''British Conchology''; London, van Voorst Vol. 1: pp. CXIV + 341 [1862
Vol. 2: pp. 479 [1864">862">Jeffreys J. G., 1862-1869: ''British Conchology''; London, van Voorst Vol. 1: pp. CXIV + 341 [1862
Vol. 2: pp. 479 [1864 Vol. 3: pp. 394 [1865]. Vol. 4: pp. 487 [1867]. Vol. 5: pp. 259 [1869] ]
Pallary P., 1920: ''Exploration scientifique du Maroc organisée par la Société de Géographie de Paris et continuée par la Société des Sciences Naturelles du Maroc. Deuxième fascicule. Malacologie (1912)'' ; Larose, Rabat et Paris pp. 108, 1 pl., 1 map

ffenzeller 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 Umbilicalis umbilicalis Gastropods described in 1778