The nervous system of Leptodora kindtii (Branchiopoda, Cladocera) surveyed with confocal scanning microscopy (CLSM), including general remarks on the branchiopod neuromorphological ground pattern.

The present study describes the nervous system of Leptodora kindtii Focke, 1844 (Branchiopoda, Cladocera) and compares it with that of other branchiopods, with the aim of determining the characters of the branchiopod neuromorphological ground pattern. L. kindtii shares certain correspondences with all studied branchiopods, including a diffuse deutocerebrum, a separated tritocerebrum and a ventral nerve cord with two commissures in each segment. We document a central complex consisting of central body, a protocerebral bridge and lateral lobes which is homologous to that recently described for the anostracan Artemia salina Linnaeus, 1758 and also known for malacostracans. Other characters in L. kindtii, such as the fused compound eye, are shared with other cladocerans, and some, such as optic fibres, the elongated circumoesophageal connectives and the short ventral nerve cord without ganglia in the thoracal part, are unique to Leptodora. The innervation of the "lateral lobes" of the "lower lip" indicates a correspondence between these lobes and the maxillules. We found evidence that the ganglia of the maxillula and maxilla segments have not been incorporated in other ganglia, as suggested earlier.