Review of the Eulimnadia (Branchiopoda: Spinicaudata) from North Africa and adjacent regions, with two new species from Mauritania

We revised Eulimnadia from a section of the northern hemisphere that spans from 18°W to 60°E longitude. We investigated both internal and external egg morphology of all available Eulimnadia in this region. Two new populations from Mauritania show a particular egg morphology and are described as new species: E. adrarensis n. sp. and E. rogersi n. sp. Both new species and E. margaretae have spherical eggs with small rectangular, narrow depressions. However, E. adrarensis has ridges with a rough surface structure whereas those of E. rogersi and E. margaretae have smooth surfaces. In addition the cross section of the egg shell shows three types of organization: in E. adrarensis there is a differentiation into two parts with a layer of large alveoli situated above a pore space; in E. rogersi the layer appears spongiform with small alveoli dotted with larger ones that are localized close to the basal layer, and; in E. margaretae the layers are more homogeneous with larger vesicules. In addition we discuss possible implications of the Mediterranean dry summer climates of this thermophilic genus distribution. The discovery of putative immature Eulimnadia in Tunisia challenges the known distribution of this genus, which was believed to be absent from the Mediterranean region, and raises some doubt about the report of Limnadia lenticularis in Sardinia. These indicate that further surveys should be conducted in the Mediterranean region in places where rains are not restricted to winter.