23 March 2011

Eobania vermiculata in my mind

Eobania vermiculata and its varieties from the Manual of Conchology (vol. 4, 1888).

I have been measuring shells of the land snail Eobania vermiculata. My purpose is to have a better understanding of the dimensional variability of the species.

In the Manual of Conchology (vol. 4, 1888), George Tryon gave the shell diameters of Eobania vermiculata as 30-35 mm. These numbers probably represented the range of average sized shells. In comparison, Kerney & Cameron in A field guide to the land snails of Britain and North-west Europe (1979) gave the diameter range as 22-30 mm, undoubtedly a truer range.

So far I have measured 78 shells collected from different locations in Turkey. The smallest and the largest adult shells were 24.8 and 31.9 mm, respectively. My largest shell is outside the upper end of the range Kerney & Cameron gave, but is smaller than Tryon's largest. On the other hand, I still have to find something as small as the lower limit of Kerney & Cameron. I have probably about 40 more shells to measure and also one lot of more than 100 shells from one locality. So these numbers are likely to change.

The measurements of the 78 shells also indicate that the variability of the combined sample is within the limits of the variability of large enough single lots. That is an interesting result about which I will write more in the future.

The next post in this series is here.

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