[Distribution and ecology of the ephemeropterans of Tunisia (1). (Insecta, Ephemeroptera)]

The study of 51 localities distributed throughout most of Tunisia has permitted the first establishment of a faunistic inventory of 11 species of Ephemeropterans (excluding Baetidae). 7 of these are newly recorded for Tunisia and one is new for North Africa. Species distributions depend essentially on chemical parameters (salinity, Cl-, Ca++, etc.) and on conductivity. Increases in the ionic concentration of the water quickly cause large decreases in population diversity, as is seen in eastern, central and southern waters. In Kroumirie, in the North West, the waters are less mineralized and so support a richer fauna. The species Caenis luctuosa possesses by far the greatest range of ecological tolerance. It is the most abundant and most frequent throughout the region, being followed by Ecdyonurus rothschildi. Distributional maps are established and the species' biogeographies and periods of flight are studied.