Umbonium

Umbonium, sometimes known as the "button top shells", is a genus of sea snails, marine gastropod molluscs in the family Trochidae, the top snails.[2]

Umbonium
Two views of a shell of Umbonium giganteum
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Vetigastropoda
Order: Trochida
Superfamily: Trochoidea
Family: Trochidae
Genus: Umbonium
Link, 1807 [1]
Type species
Trochus vestiarius
Synonyms[2]
  • Globulus Schumacher, 1817 (objective synonym of Umbonium)
  • Rotella Lamarck, 1822
  • Suchium Makiyama, 1924

Shell description

The shells of the species in this genus are low-spired and shaped like a button. The orbicular shell is depressed and imperforated. It is polished, porcellaneous and has a very thin pearly layer inside. The whorls are flattened above, bright, smooth or spirally grooved. The small, transverse aperture is wider than high. The thin outer lip is acute. The inner lip is rounded, ending in a simple point. The umbilicus of the shell is often completely covered with a thick and smooth callus.[3]

Anatomy

The animal has a distinct lateral fringe of the foot, with three filaments on each side. The front of the right side near the base of the tentacles is produced into a fleshy lobe. The right tentacle is free, with the eye-peduncle compressed, and bears a rudimentary eye. The left eye-peduncle is cylindrical, with a distinct eye, and furnished with an expansion or frontal lobe, which is folded on itself and fringed at its free margin. The operculum is horny, orbicular, and multispiral.[4]

Species

Species in the genus Umbonium include:

Species brought into synonymy

References
  1. Link J. H. F. (1807). Beschr. Nat. Samml. Univ. Rostock (3): 136.
  2. Bouchet, P. (2012). Umbonium Link, 1807. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=205005 on 2012-12-04
  3. Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
  4. Proceedings of the Zoological Society of London pt. 21-23 (1853-1855) p. 186
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