28th February 2015 (weekly review)

February has reached its close and I have attained a grand total of 20 snail species on my quest. That’s ten species per month, so far, so keeping up that rate should see me achieve my overall target by the end of the year. Of course, the species I’m finding at the moment are relatively easy species to find and it will only get more difficult as the year progresses. My two new species this week were:

Clausilia bidentata, the Two-toothed Door Snail

This is my second clausilid species of the year, after Cochlodina laminata, and it’s probably the most widespread British species of door snail. Whilst Cochlodina laminata climbs trees occasionally in wet weather, Clausilia bidentata is often found on trees or walls. It grows to a maximum of 12mm tall and the shell generally looks quite ‘rough’ due to the density of ribbing. It also usually is marked with flecks of white.

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The specific name – bidentata – clearly means the same as the common name; two-toothed, but I am not actually sure as to why it has been called this. There are two lamellae in the mouth of the shell – which could be referred to as teeth – but this is true of most of the UK clausilids.

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The below picture shows an adult Clausilia bidentata (bottom) next to a sub-adult Cochlodina laminata (top). Note the size difference and how rough C. bidentata looks in comparison.

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Nesovitrea hammonis, the Rayed Glass Snail

This is a very widespread species – recorded pretty much everywhere according to NBN – but is possibly over looked due to its small size (a smidge over 4mm fully grown) and the fact that its shell only ever grows to have 3 ½ whorls, which gives it a ‘juvenile’ appearance. It does, however, have one very distinctive feature: its shell is strongly marked with radial striations which can be easily seen at low magnification. This gives it the common name of the Rayed Glass Snail.

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A better picture by @BrianE_Cambs:

Neso - Brian Eversham

This snail is one of the elite few that are tolerant of soil acidity and indeed the specimen that I photographed was found at The Lodge RSPB on the edge of the heath.

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Hopefully I can find at least another ten species in March to keep myself on target. I’m hoping for some warmer weather to bring a few more species out of hibernation.

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