We are all familiar with the idea that scientific names provide a stable, universal way of referring to species. Nevertheless, as taxonomists investigate matters more closely, new relationships and differences are discovered, and species are placed in different genera, or even given completely new names. For the amateur in particular this can be quite confusing, and sometimes when one looks at the older literature one comes across species that have apparently ceased to exist. Even when we know what the new names should be, it can take a long time for us to adapt mentally. It took me several years to stop calling certain slugs Agriolimax after they had been changed to Deroceras, and I still think of Milax budapestensis instead of Tandonia budapestensis, as we should now call it. Now that Deroceras caruanae has become D. panormitanum it is not only unpronounceable, but nearly unspellable as well! I know I am not alone in being unable to get used to new names.
The latest revision of the names of British non-marine molluscs was published by Roy Anderson late in 2005 (Journal of Conchology 38, pp 607–637), with some more recent amendments on the Conchological Society website (www.conchsoc.org). Although many names have remained unchanged (including, thankfully, all the freshwater bivalves, and all Vertigo species, for example), there have been some quite substantial changes as well. In the following tables, I have tried to compare old and new names (where these have changed), with the aim of answering two types of question. First, what is the latest name for a particular species? For example, reference to the appropriate table will show that the species called Amnicola taylori by Ellis (British Snails, 1926) should now be called Marstoniopsis insubrica. The second question is: what did we used to call this species with the strange name that everybody seems to be using now? Radix balthica, for example, turns out to be our old friend Lymnaea peregra (or Limnaea pereger).
In a few cases, the phrase “Not recognised in previous works” appears against the new name. this indicates that the species is either a new introduction to the British Isles, or has not previously been recognised as a separate species although it may have been here for a long time. Sometimes (particularly with slugs), there is more than one new name against a single old name. This is because it has been recognised that what was formerly regarded as a single species should be split up into two or more. I have not attempted to cite full references for these.
There are separate tables for freshwater snails and for terrestrial species. This is not only because it keeps each table to a manageable size, but also because I have used some different key works for the older names. Within each table, the species are arranged simply in alphabetical order in the first column; there is no attempt at a taxonomic arrangement. Nor have I tried to produce a formal synonymy, which would not only be beyond me, but would probably cause more confusion than clarification.
I hope these lists will be useful, and help to make the transition to the new names easier – until the next revision! Acknowledgement: Roy Anderson has kindly looked over the material in this article, but any remaining errors are due to me.
NOTE - the tables have not been reproduced here but can be viewed by downloading the pdf copy.