Alinda biplicata

Alinda biplicata, also known as Balea biplicata, common name the two-lipped door snail or Thames door snail, is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Clausiliidae, the door snails, all of which have a clausilium.^{[3] [4][5]}

Alinda biplicata
Shell of Alinda biplicata
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Stylommatophora
Family:	Clausiliidae
Genus:	Alinda
Species:	A. biplicata
Binomial name
Alinda biplicata (Montagu, 1803)[2]
Synonyms
Turbo biplicata Montagu, 1803 Balea biplicata (Montagu, 1803) Laciniaria biplicata

Distribution

This species is known to occur in several European countries and islands, including:

Distribution of Alinda biplicata

• Czech Republic
• Poland
• Slovakia
• Hungary
• Romania
• Bulgaria
• Greece
• Slovenia
• Croatia
• Serbia
• Switzerland
• Austria
• Germany
• France
• Belgium
• Netherlands
• Denmark
• Sweden
• Great Britain

This species is rare in Great Britain. In England, it is found mainly in the London area, almost exclusively along the River Thames, and is particularly preserved at Isleworth Ait.^[6] There is also a colony at Purfleet in Essex.^[7]

The internal shell anatomy of the body whorl of Alinda biplicata
1 - Lamella superior
2 - Lamella inferior
3 - Lamella subcolumellaris
4 - Lunella
5 - Clausilium
6 - Plica medialis
7 - Plica principalis
8 - Lamella spiralis

Description

Like all species in this family, this snail has a clausilium. This spoon-shaped "door" is supported by, and slides in, a series of internal shell folds, see the image below.

The weight of the adult live snail is 149±6 mg.^[8]