Ben Rowson, National Museum of Wales, Cardiff, UK
Malacologists in the British Isles - and further afield - are asked to let us know of any sightings of the "Ghost Slug" Selenochlamys ysbryda. My colleague Bill Symondson (Cardiff University) and I described this blind, earthworm-eating terrestrial species of the family Trigonochlamydidae (Pulmonata: Stylommatophora) in the latest issue of the Journal of Conchology. The description was based on a breeding population found in 2007 in a household garden in Cardiff, South Wales, UK. The Trigonochlamydidae are otherwise endemic to the Caucasus region of eastern Europe and Asia Minor, so S. ysbryda is evidently an accidental, and probably recent, introduction. Being edaphobitic (soil-dwelling) the species could readily disperse passively in soil or compost transferred from garden suppliers or between gardens. There is thus a concern that S. ysbryda will become invasive or even a horticultural pest, as has the New Zealand Flatworm Arthurdendyus triangulatus in some parts of the British Isles.
As such we aim to clarify the slug's distribution and potential spread. Here the unusual appearance of the "Ghost Slug" may prove helpful. Although elusive, rarely appearing above ground, it is so conspicuous that it would almost certainly have been noticed by naturalists had it been present in the UK for long. Thus it appears we are in the early stages of its establishment. Secondly, the species is distinctive enough that potentially any observer can identify it, allowing records to be verified from photographs alone. Some recent publicity in the local and national news, and online, has generated a good response from the British public, with "sightings" reported from all over the UK and Ireland. Despite our best efforts, most of these turn out to be the limacid slug Deroceras reticulatum, but verified records of S. ysbryda have now been received from the towns of Caerphilly and Gorseinon (the latter approximately 50 km from Cardiff). It seems the species is well-established in South Wales, and a density of records in central Cardiff may even reflect some active dispersal between gardens. It may still occur elsewhere, and here we appeal to malacologists (with their superior identification skills) to inform us of any plausible sightings. Digital photographs, or better yet, live or preserved specimens, are still needed to verify records, and should be sent to the email/postal address given on the website below. This page, aimed at the general public, also includes further details on identification. We would be grateful to hear from you!
National Museum of Wales "Ghost Slug" page:
Description of S. ysbryda:
Rowson, B. & Symondson, W. O. C. 2008. Selenochlamys ysbryda sp. nov. from Wales, UK: a Testacella-like slug new to Western Europe (Stylommatophora: Trigonochlamydidae). Journal of Conchology 39 (5): 537-552.
S. ysbryda adult
S. ybsryda young juvenile