Euchelus atratus

Euchelus atratus
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Vetigastropoda
Superfamily:	Seguenzioidea
Family:	Chilodontidae
Genus:	Euchelus
Species:	E. atratus
Binomial name
Euchelus atratus (Gmelin, 1791) [1]
Synonyms
Angaria atrata (Gmelin, 1791) Euchelus denigratus Chemnitz [2] Monodonta tamsi auct. non Dunker, R.W. Monodonta punctulata auct. non Lamarck, J.B.P.A. de, 1822 Nerita atrata Gmelin, 1791 Trochus canaliculatus Lamarck, 1818 Turbo atratus Gmelin, 1791 (original combination)

Euchelus atratus, common name the blackish margarite, is a species of sea snail, a marine gastropod mollusk in the family Chilodontidae.^[3]

Description

The size of the shell varies between 5 mm and 21 mm. The solid, umbilicate shell has a globose-conic shape. Its color is black, brown, or grayish-pink, either unicolored or tessellated with dark spots. The conic spire is short. The sutures are deeply canaliculate. The 5-6 convex whorls are encircled by numerous equal, densely, finely beaded spiral ribs, with deep interstices, in each of which an interstitial riblet arises on he last part of the body whorl. The spiral ribs on the penultimate whorl number 7 to 9. On the body whorl they number 12, exclusive of the interstitial riblets. The convex body whorl is rounded, quite abruptly and decidedly descending at the aperture. The rounded aperture is strongly, finely sulcate inside. The columella is straight, with a small projecting tooth at base. The umbilicus is deep, bounded by a strong white rib, about 1 mm. diameter.

Larger specimens (16–23 mm. alt.) are paler, and have a small riblet developed in each interstice, thus about doubling the number of spirals.^[4]

Distribution

This species occurs in the Red Sea and in the Indian Ocean off the Mascarene Basin.

References

1. Gmelin, Syst. Nat. xiii, p. 3601
2. H. & A. Adams, Genera, t. 47, f. 6.
3. Euchelus atratus (Gmelin, 1791).  Retrieved through: World Register of Marine Species on 28 March 2012.
4. Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia

• Drivas, J. & M. Jay (1988). Coquillages de La Réunion et de l'île Maurice
• Higo, S., Callomon, P. & Goto, Y. (1999) Catalogue and Bibliography of the Marine Shell-Bearing Mollusca of Japan. Elle Scientific Publications, Yao, Japan, 749 pp.
• Herbert D.G. (2012) A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean. African Invertebrates, 53(2): 381–502

External links

• Gastropods.com: Euchelus atratus