Morphological differentiation of the genus Niphargus (Amphipoda) on Corsica — a numerical approach

A short introduction is provided on the taxonomic status of the genus Niphargus, especially on the species related to N. longicaudatus corsicanus. Previous findings and descriptions are mentioned. An attempt is made to clarify the relationships between Corsican Niphargus populations by means of a cluster analysis and a principal components analysis combined with a cluster analysis. Special attention has been paid to the size-dependent variability of most of the characters. The results of both methods of analysis are compared with each other and evaluated. The morphological differentiation between populations is, on the average, greater than within populations. This, along with the large amount of character variability, makes it very difficult to fit populations into, or to distinguish them from, any of the — often poorly described — taxa of Niphargus.