SYSTEMATICS AND BIOGEOGRAPHY OF THE LAND MOLLUSCA OF NW-AFRICA .7. TAXONOMY, ECOLOGY AND DISTRIBUTION OF LEIOSTYLA IN W-EUROPE AND NW-AFRICA (GASTROPODA, PUPILLIDAE)

The status of Leiostyla in the Iberian peninsula and NW. Africa is rev iewed. Examination of material of Leiostyla anglica from Britain and I reland showed that shell characters such as size, shape, colour and de velopment of apertural teeth were variable within and between populati ons. Shells of Leiostyla numidica from Algeria were also found to be v ariable. As the main distinguishing characters are shape of the shell and the absence of a basal plica and as both characters are variable, it is difficult to justify the separation of Leiostyla numidica. Facto rs influencing the range of Leiostyla in NW. Europe are discussed.