Xerocrassa is a genus with many endemic species in the Balearic Islands. In most cases, we can find two main forms in these species, a) the form of the Pitiusas (bigger and rounded) and b) the form of the Gimnesias (flattened with very pronounced ribs and keels). This genus is a good example in order to explain the radiation on islands as it presents high species diversity, especially in isolated islets.
