The status of Phenacolimax major in U.K.
Project Co-ordinator: David Long
The Society has been carrying out a survey for P. major during the periods November 2004 – end May 2005, November 2005–end May 2006, November 2006 – end May 2007, and will continue from November 2007 – end June 2008. The results will be published in the Journal of Conchology.
The survey started with sites from which P. major had been recorded in the past. Other apparently suitable sites are being visited as time permits. We still need volunteers to assist in completing the work.
Phenacolimax major, the Greater Pellucid Glass Snail, is an uncommon semi-slug found in Britain (post-1965) in 59 10 x 10 Km. grid squares in southern England and south-east Wales, with pre-1965 records in four further squares; elsewhere its main range is in France and west Germany. (Kerney, Atlas of the Land and Freshwater Molluscs of Britain and Ireland, 1999. page 135). We do not know if it is in decline or holding its own in Britain; it could be as rare as the Mountain bulin (Ena montana), but it does not have any particular conservation status - should it?
In Britain, one other semi-slug, the widespread Vitrina pellucida, is associated with it . Both species are annuals, maturing, breeding and then dying off in the Spring. P major is found into May and early June rather later than V. pellucida which disappears by the end of April, or earlier. Here, P major is associated with old woods, perhaps especially with wetter places near springs, streams and flushes, whereas V pellucida occurs in a variety of habitats - woods, vegetated stone walls, grasslands, and even gardens.
Live animals of P major differ externally from V pellucida in having a slightly flatter shell and a mantle edge which extends back over the shell to reach the apex; the mantle is also often blotched with black. V pellucida has a much smaller mantle edge with a small dark mark near the mantle opening. There are also difference internally, in the reproductive system (see Kerney and Cameron "A field guide to the land snails of Britain and north-west Europe", 1979, pages 109 and 115 ).