Calliostoma

Calliostoma
A live individual of Calliostoma ligatum with the operculum showing at the back (on the left)
Apertural view of a shell of Calliostoma trotini
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Vetigastropoda
Superfamily:	Trochoidea
Family:	Calliostomatidae
Subfamily:	Calliostomatinae
Tribe:	Calliostomatini
Genus:	Calliostoma Swainson, 1840[1]
Type species
Trochus conulus Linnaeus, 1758
Species
See text

Calliostoma is a genus of small to medium-sized sea snails with gills and an operculum, marine gastropod molluscs within the family Calliostomatidae, the Calliostoma top snails (according to the taxonomy of Gastropoda by Bouchet & Rocroi (2005)). Previously this genus was placed within the family Trochidae. Calliostoma is the type genus of the family Calliostomatidae.

The name of this genus is derived from the Greek words kallos (beautiful) and stoma (mouth), referring to the pearly aperture of the shell. The genus Calliostoma is known in fossil records from the Upper Cretaceous onwards.^[2]

The distribution of this genus is worldwide, found mainly on hard substrates, although Japanese species have been found on sandy bottoms. These snails occur from shallow waters to bathyal depths.

The species in this genus are mainly herbivorous or feed on detritus,^[3] although a few have been observed to be omnivorous (Keen, 1975) or even carnivorous, feeding on a wide range of algae and on animals belonging to various other invertebrate phyla.^[4] The North Atlantic topshell Calliostoma occidentale has been reported to feed on coelenterates.^[5]

Contrary to what is the case in most other top shells, Calliostoma deposits its eggs in gelatinous ribbons that are only fertilized after being deposited. The young emerge as small snails (Lebour, 1936) without passing through a free-living planktonic stage as a veliger larva.

Drawing of a dorsal view of a living animal of Calliostoma bairdii dredged in the Atlantic Ocean at a depth of from 100 m to 1170 m.

Rare purple beaded specimen of Calliostoma supragranosum found subtidally in Southern California.

Description

The rather thin, acute, coeloconoid (= approaching conical shape but with concave sides) shell is imperforate or rarely umbilicate. The whorls are smooth, often polished and spirally ridged or granular. The body whorl is angulated at the periphery. The aperture is quadrangular, sinuated at the base and slightly oblique. The columella is simple, usually ending anteriorly in a slight tooth.^[6] The nucleus appears to be either dextral or sinistral indifferently.^[7][8]

Species

Currently, Calliostoma is being treated in WoRMS as a broad genus. It is expected to be broken up and (some) subgenera will be elevated to the status of genus. At this moment (2013), information is too fragmentary to assign all species in a revised genus.

Species within the genus Calliostoma include:^[9]

Species brought into synonymy

^[9]

References

• Vilvens C. (2012) New species and new records of Seguenzioidea and Trochoidea (Gastropoda) from French Polynesia. Novapex 13(1): 1-23. [10 March 2012] page(s): 18

Further reading

• Marshall, B.A. (1995). "A revision of the recent Calliostoma species of New Zealand". The Nautilus 108: 83–127. 
• Quinn, J.F. Jr. (1992). "New species of Calliostoma and notes on some poorly known species from the Western Atlantic". The Nautilus 106: 77–114. 
• Rosenberg G. (2005). "Malacolog 4.1.0: : A database of Western Atlantic Marine Mollusca". Retrieved 18 March 2009. 
• Williams, S.T.; K.M. Donald; H.G. Spencer; T. Nakano (March 2010). "Molecular systematics of the marine gastropod families Trochidae and Calliostomatidae (Mollusca: Superfamily Trochoidea)". Molecular Phylogenetics and Evolution. 3 54 (3): 783–809. doi:10.1016/j.ympev.2009.11.008. PMID 19919851. Retrieved 20 May 2010. 
• Vilvens C. (2009). New species and new records of Calliostomatidae (Gastropoda: Trochoidea) from New Caledonia and Solomon Islands. Novapex 10(4): 125-163

External links

Wikimedia Commons has media related to Calliostoma.

• To GenBank
• To ITIS
• To World Register of Marine Species