Variación del tamaño de la concha en tres especies de caracoles terrestres (Chondrinidae, Hygromiidae) respecto al gradiente altitudinal en los Pirineos

The altitudinal variation in shell size of land snails has not a precise pattern. Some species show a dependency of the size shell on altitude but other tests give no significative results. Three species, Abida secale, Granaria braunii and Xerocrassa salvanae, with a large range of altitudinal distribution and similar habitat selection, have been studied in the restricted area of a valley at the East Pyrenees. The measured shell parameters (height, maximum diameter, relative height and volume) have not been meaningfully related to altitude, with the exception of the shells of X. salvanae that diminishes with altitude. Other factors than altitudinal gradient should explain the variability in shell size measured in the studied species.