The diversity of terrestrial Isopoda in the Berkoukech area, Kroumirie, Tunisia

Until now, no investigations have been made on the diversity of woodlice in any region of Tunisia. In the framework of the "MEDCORE" project, particular emphasis has been put on the study of terrestrial isopod diversity in the Berkoukech area (north-west of Tunisia). Two sites were selected for this study: the beach dune system and an inland site located in Rabouet Bou Ali. In the beach dune system, isopods were studied in three biotopes: a grazed meadow (biotope 1), a maquis of Pistacia lentiscus, Quercus coccifera, Erica arborea, Phylleria angustifolia, and Callycotome villosa (biotope 2), and a climax forest of Quercus coccifera, Juniperus oxycedrus, Juniperus phoenicea, and Callycotome villosa (biotope 3). In Rabouet Bou Ali, a Quercus suber forest (biotope 4) was chosen for study. In the Berkoukech area, 12 species of terrestrial isopods belonging to five families were collected: Tylidae, Porcellionidae, Philosciidae, Platyarthridae, and Armadillidiidae. Among these, two species are reported as new for Tunisia. Furthermore, this study indicates that isopods are not evenly distributed in the various biotopes: they vary in number of species as well as in number of specimens. Biotope 2 shows the highest diversity and is the most homogeneous (Is = 3.16; H′ = 1.76; J′ = 0.88), while biotope 4 exhibits the lowest values (Is = 1.2; H′ = 0.475; J′ = 0.3). The similarity between the various communities, estimated by the Bray-Curtis index, shows that the biotopes cluster according to their plant associations.