The reality of spatial clinal variation in morphological traits of freshwater pulmonate snails (Gastropoda: Pulmonata) has repeatedly been questioned or totally discounted. There is a lack of sound statistical evidence in the articles hitherto published on this subject supporting these claims. Here, by means of different analytical methods (analysis of spatial autocorrelation, linear regression analysis, canonical correlation analysis and others), we demonstrate that shell variation in the dwarf pond snail, Galba truncatula, is patterned in space throughout the northern and central Palearctic, with latitudinally-oriented clines in body size and in some shell proportions. Shell size in G. truncatula decreases with latitude and temperature, representing a special case of converse Bergmann cline. However, the temperature itself is hardly the main driver of shell size variation. It is argued that the shorter growing seasons at high latitudes may represent a better explanation for the observed trend. Shell proportions in the dwarf pond snails vary weakly at the macrogeographic scale, being spatially patterned at lower (mesogeographic) scales around 1200–1500 km. In general, spatial variation in G. truncatula shell size is decoupled from variation in shell shape, demonstrating clear scale-dependence similar to that found in different species of terrestrial (non-aquatic) pulmonate snails.

淡水肺蜗牛（Gastropoda：Pulmonata）的形态特征在空间上的倾斜变化的现实已经被反复质疑或完全打断。迄今为止，在有关该主题的文章中缺乏可靠的统计证据来支持这些主张。在这里，通过不同的分析方法（空间自相关分析，线性回归分析，典范相关分析等），我们证明了侏儒池塘蜗牛Galba truncatula的壳变化在整个北北中部的空间中都具有规律性，在身体尺寸和某些壳比例上具有纬度取向的cline。壳尺寸G.蒺藜随纬度和温度而减小，代表逆向Bergmann氏谱的特殊情况。但是，温度本身几乎不是壳尺寸变化的主要驱动力。有人认为，在高纬度地区较短的生长季节可能是对观测到的趋势的更好解释。矮池塘蜗牛壳的比例在宏观地理尺度上变化很小，在较低的尺度（中地理）大约在1200-1500 km范围内具有空间格局。总的来说，run藜壳尺寸的空间变化与壳形状的变化是脱钩的，这表明其明显的尺度依赖性类似于在不同种类的陆生（非水生）肺蜗牛中发现的尺度依赖性。