Smallest British snail
I have recently identified, with some satisfaction as 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 2014. It 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. These give 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