Un branchiopode nouveau pour la France : Eulimnadia sp. (Crustacea, Branchiopoda, Limnadiidae) découvert dans le nord de l'Alsace (Grand-Est, Bas-Rhin)

Abstract  ̶  A branchiopod new to France: Eulimnadia sp. (Crustacea, Branchiopoda, Limnadiidae) discovered in northern Alsace (North-Eastern France)

An allochthonous branchiopod species belonging to the genus Eulimnadia Packard, 1874, which is morphologically very close to Limnadia lenticularis (Linnaeus, 1761), was first observed in 2015 at Munchhausen (Bas-Rhin) in the Sauer Delta National Nature Reserve. This is the first observation of this genus in France and in western and continental Europe. Between 2017 and 2023, research was carried out to determine its distribution and our results show that this species occurs at four sites in the Upper Rhine Valley between Munchhausen and Lauterbourg (Bas-Rhin, northern Alsace). We postulate that Eulimnadia sp. could be a threat to the endangered Limnadia lenticularis due to its shorter life cycle, multi-seasonal reproduction and thermophilic preferences. This article provides morphological criteria to assist naturalists in distinguishing this new species from Limnadia lenticularis in the field.