Genus: PLANORBARIUS Froriep, 1806
Only one species of this genus occurs in northern Europe.
Planorbarius corneus
(Linnaeus, 1758)
Planorbarius corneus (Linnaeus, 1758)
Description: This is the largest British member of the family Planorbidae, and may reach a size in excess of 35 mm. in diameter. The shell is comprised of 5 - 6 glossy whorls, with a deep suture. There is no keel, the periphery being well rounded. The growth lines are close-set and irregular. The mouth aperture is large and almost circular. The spire is slightly depressed below the level of the body whorl, and the umbilicus is very wide and deep.
Size: Height: 9 – 12 mm. Breadth: 20 – 36 mm.
Habitat: It lives in marshes, ponds, rivers and canals, and is found locally in most of the southern counties and the Midlands of Britain. It is sometimes found elsewhere, but it has to be considered as possibly an introduction as it is often introduced by anglers.
Juveniles are proportionately higher, with fewer whorls and a strongly flared mouth.