Smallest British snail

December 13th 2014

Smallest British snail

I have recently identified, with some satisfaction (being a beginner in this field), an example of the smallest British land mollusc. It was in a batch of snails collected by Stephen Moran at Kearvaig, near Cape Wrath (NC2972) on 23rd August, and is appropriately named the dwarf snail Punctum pygmaeum. When fully adult it reaches a diameter of 1.5 mm, but this example was just 0.64 mm across. It is a miracle that Stephen even saw it amongst the rather larger insects he was sampling with his suction collector in an area of ‘sedgy dunes’. Fortunately, the shell has a good diagnostic character when seen under a low-power microscope; the growth rings are raised into sharp ridges, giving it the appearance, in profile, of a tiny fine-toothed cog-wheel.

I know that Cape Wrath is well outside Assynt, but the species has been recorded locally: from Ardvar (NC1833) and the eastern end of Loch Assynt (NC2423) in 1977 by Martin Willing; from Inchnadamph (NC2521) in 1998 by Dorothy Marriott; at Ardvreck Castle (also NC2423) in 1996 by Barry Colville. The mollusc Atlas (Kerney, 1999) says tellingly ‘under-recorded owing to its minute size’. So, something for the keen-eyed to look out for locally, amongst leaf-litter in woodland, as well as marshes, grassland and the wetter parts of dunes.

Ian Evans

Dwarf snail Punctum pygmaeum, Photo D. Haines
Dwarf snail Punctum pygmaeum, Photo D. Haines

Report a Sighting

Recent Sightings

Whooper Swan

three birds on River Loanan near Inchnadamph (DAH) (20/11)

Teal

nine birds, Loch na Claise (DAH) (17/11)

Goldeneye

two male birds, Loch na Claise (DAH) (17/11)

Red-throated Diver

two winter plumage birds, Bay of Culkein (DAH) (17/11)

Redshank

four birds, Bay of Culkein (DAH) (17/11)

Turnstone

four birds, Bay of Culkein (DAH) (17/11)

Oystercatcher

32 birds, Bay of Culkein (DAH) (17/11)

Great Northern Diver

single bird, Clashnessie Bay (Gwen Richards and Ian Evans) (16/11)

Map