Snail Trail 2015 - January 2015

Hi all.

I just thought I'd best share the snail species I have seen so far this year. In January I saw a total of twelve species. If I can keep this rate up, month by month, by the end of the year I'll have easily seen all the land snails and more.

So, without futher ado, my 12 species from January:

Vitrina pellucida, Winter Semi-slug or Pellucid Glass Snail

A common and widespread species, easily found in disturbed habitats such as gardens, wasteland and brownfield sites. It is usually found as an adult during the winter months, hence one of its common names ‘The Winter Semi-slug’. The ‘semi-slug’ part of the name refers to the way that the body of the snail wraps over part of the thin, translucent shell, giving it appearance that could be considered intermediate between slugs and snails. I’ve found multiple examples of this species so far, with the pictured example below found in a garden in Hull.

Vitrina pellucida

Lauria cylindracea, Common Chrysalis Snail

Another very common and widespread species, but usually overlooked. I’ve probably found more than fifty of these so far this year, but when I show people the most common response is: “Wow, I’ve never seen a snail so small before!” At a maximum of 4.4mm tall (and usually smaller) that’s understandable. If turning over rocks or stones, have a really close look at the underside. Lauria cylindracea is often present.

Lauria cylindracea

Oxychilus alliarius, Garlic Snail

This snail is a real crowd-pleaser. A garlic snail, when disturbed, produces a strong garlic-scented odour, hence both the common and scientific appellations. It is not the only snail to produce a garlic aroma when bothered; its close congener Oxychilus navarricus does something similar but with a weaker and less pungent scent. Later in the year, once I have found a specimen of O. navarricus, I will run through how to differentiate them.

Oxychilus alliarius

Merdigera obscura, Lesser Bulin

I must confess to not knowing what the common name of this species means; what exactly is a ‘bulin’? The scientific name, unusually, is easier to understand, ‘merdigera’ meaning ‘excrement bearer’ and ‘obscura’ meaning ‘hidden’. Essentially, a snail hidden by its own excrement. The species bears this name because of its habit of coating its shell in dirt, faeces and algae – possibly for reasons of camouflage? You can see that the shell in my, frankly underwhelming, photo below has some matter adhering to it.

Merdigera obscura

Vallonia costata, The Ribbed Grass Snail (or, rarely, the Costate Vallonia)

The genus Vallonia comprises three species in the UK, of which I have found V. costata the most common/easiest to find, as well as the most distinctive of the group. The UK Vallonia species are a pleasant whitish-ivory colour, and all are under 3mm fully grown. Fresh, mature and unworn V. costata can be easily distinguished from the others due to the stout ribbing of the shell. In fact the specific name – costata – comes from the Latin ‘costa’ meaning ‘rib’. ‘Vallonia’ apparently comes from the Latin for ‘from the vale’ or ‘shallow valley’, presumably as a reference to the grassy habitats where this genus can be found.

V. costata is a species of calcareous grassland; usually dry in my experience. The most reliable spot I know for the species is in Potton churchyard, Bedfordshire, where I find it commonly on top of a particular tomb – I imagine the stonework is calcium-rich. The photo below has been the most popular photo I have yet shared on Twitter; I think people appreciate a sense of scale when dealing with very small species.

Vallonia costata

Oxychilus draparnaudi, Draparnaud’s Glass Snail

Last week I found Oxychilus alliarius, the Garlic Snail, the smallest of the four UKOxychilus species. This week, I bring you Oxychilus draparnaudi, the largest UK species in the genus at a maximum of around 16mm. This snail does not produce a garlic scent at all (which can help distinguish it from O. alliarius and O. navarricus) and has a noticeably smaller umbilicus than O. cellarius.

Oxychilus draparnaudi is a non-native species within the UK, but it seems to been present here for some time; I haven’t found any first dates of discovery. It also appears to be relatively benign introduction or, at least, I haven’t found reference to it causing a nuisance.

In my experience, Oxychilus draparnaudi is usually found in gardens, parks and other urban and semi-urban areas. It may be that it does particularly well in areas with human disturbance.

Oxychilus drapa

Trochulus striolatus, The Strawberry Snail

Trochulus striolatus is another very common species. I’ve found it mainly around the flowerbeds and the bases of hedges in urban areas and other damp and/or humid areas; the first one I ever identified was crawling across my doorstep after rain. Its common name ‘The Strawberry Snail’ is probably derived from its habitat; living amongst low plant growth such as strawberries. Its scientific specific name ‘striolatus’ come from the Latin for ‘bearing narrow markings’ which probably refers to the coarse growth lines on the shell.

Juvenile Trochulus striolatus bear a few scattered hairs on the shell that are lost once it matures. There are two other species in the genus Trochulus in the UK, T. hispidus and T. sericeus. These are both smaller at full size, and both often retain hairs on the shell into adulthood.

Strawberry Snail

Hygromia cinctella, the Girdled Snail

This species was kindly shown to me by Africa Gomez of @abugblog in the Pearson Park Wildlife Garden in Hull. This snail has a distinctively patterned and shaped snail. It has the form of a very shallow cone, with a rounded base, and is marked with a white line that encircles, or ‘girdles’, the shell. This white line follows a sharp ridge or ‘keel’ that runs around the shell and, combined, these features make it an easy species to distinguish. Maximum width of shell is 12mm.

Girdled Snail3

The Girdled Snail is a non-native species; first described in Britain in 1950 by writer Alexander Comfort. There are, however, records of this species that extend back to 1945 but were misidentified at the time as being Hygromia limbata. The species remained fairly restricted to the south-west until the 1970’s, at which point it began to expand dramatically, being recorded in Scotland for the first time in 2008. The Girdled Snail is native to the Mediterranean region and it surprises me how well it seems to cope – and thrive – in the UK.

Girdled Snail1

Africa pointed out to me that the Wikipedia article on Girdled Snail was a ‘stub'; an incomplete article with less than 500 words. Working together, we updated and improved the text on the page, and Africa added some of her own photos. View our success here!

Discus rotundatus, the Rounded Snail, Rotund Snail, or Discus Snail

Discus rotundatus is one of my favourite UK snails. I remember the first time I saw it being struck by its wonderful mottling in shades of brown, pink and cream, as well as that densely ribbed shell. It grows up to about 7mm in maximum diameter and is commonly found in moist, shaded places such as parks and graveyards, as well as in more natural habitats such as woodland.

Discus rotundatus3

Cornu aspersum, the Common or Garden Snail

This is one of those species that’s possible just to ramble on about endlessly. Firstly, this is the beast that quite possibly gave rise to the phrase ‘common or garden’. It’s not often you meet an invertebrate with its own idiom! It’s also the largest of the common snail species – about 40mm in width – with only two other less-common UK species, Helix pomatia and H. lucorum, being larger.

Cornu aspersum1

Cornu aspersum was, for many years, called Helix aspersa. It was then decided that it didn’t belong in the genus ‘Helix’ and was moved to ‘Cornu’. However, whilst ‘Cornu’ was the name given to material identifiable as this species, the original specimen was an aberrant scalariform individual (a snail in which the whorls of the shell grow apart from each other). This, according to some schools of thought, means that the genus name is invalid. A summary of this problem can be read here.

Numerous hibernating individuals can often be found over winter, gathered together under logs or in cracks in trees or rocks. If a hibernating snail is dislodged it should be possible to see the congealed film or plug of mucus that seals the moth of the shell; this is called an epiphragm.

Cornu aspersum2

Cornu aspersum is another non-native snail, but this one is an ancient, possibly Neolithic introduction. It is common in parks and gardens as well as other areas modified by people.

Vallonia excentrica, the Eccentric Vallonia

This is my second Vallonia species of the year. I’ve only got one species in this genus left to go now, Vallonia pulchella.

I found these in an abandoned quarry near Potton, Bedfordshire. Clearly, they must have spread into the site since the quarry was abandoned. Unfortunately I don’t know how long ago the quarry ceased operations, otherwise that could give a rough idea of the power of dispersal that these snails have.

There is a fair amount of detritus scattered around in the quarry – bits of wood, stone, plastic etc., – and these serve as excellent places to try and find Vallonia. However, in my experience, Vallonia only seem to be found under refugia that have been relatively recently moved. Bits of stone or wood that have been there too long kill off the grass underneath and I never find Vallonia in these circumstances. Recently moved refugia, which have been in place just long enough to make the grass go slightly yellowish and sad-looking, seem to be the best places to search. Usually the shining, ivory shell of Vallonia is not too difficult to spot in these situations.

Vallonia excentrica can be easily differentiated from V. costata by the lack of heavy ribbing on the shell, as well by the way that the outermost whorl of the shell expands rapidly, giving it an ‘eccentric’ or ‘unbalanced’ appearance. This, obviously, gives it both its common and scientific names. Distinguishing between V. excentrica and V. pulchella is more subtle, and will be discussed if-and-when I find that species.

vallonia excentrica

Cepaea nemoralis, the Brown-lipped Snail

I can’t believe how long it took me to find this species, especially with how large, common and colourful it is. All I seemed to be able to find were empty shells. Amusingly, after spending some time searching for this species, I found this one half-heartedly and absent-mindedly whilst aimlessly turning over logs whilst chatting to my Mum on my phone during my lunch break.

C. nemoralis 2

There are two Cepaea species in the UK; C. nemoralis and C. hortensis. Cepaea nemoralis is the larger of the two species – growing up to a max of 25mm in width – and usually has a brown lip to the mouth of the shell in mature specimens, hence the common name. Cepaea hortensis, by contrast, usually has a white-lip to the shell. Of course, rules are made to be broken, and in some areas of the UK Cepaea nemoralis occurs in populations that contain forms with a white-lip. In these cases it is probably best to:

  1. Look at the maximum sizes of shells (nemoralis is larger than C. hortensis)

  2. Ask an expert to dissect for confirmation

  3. Give in and look elsewhere for more cooperative snails.

The scientific name comes from the Greek ‘cepaea’ meaning ‘of the garden’ and the Latin ‘nemoralis’ meaning ‘of the woods’. This is a fair descriptor of habitat, as the species tends to favour habitats disturbed by humans, such as gardens, parks, arable land and roadsides.

C. nemoralis 4

Cepaea nemoralis is almost obscenely polymorphic, occurring in a staggering array of colours and patterns, even within a single population. This collection of drawings and this photograph do a marvellous job of demonstrating variation. They also exhibit rapid, habitat related evolution when colonising areas from which they were previously absent – thanks to @schilthuizen for the article.


If anyone knows any sites for less-common snails (I'm thinking the Vertigo snails in particular) then please let me know. I'd like to meet up with fellow pan-listers to tick of an obscure snail.

Consider following me on Twitter @UKSnailTrail