SYNTOPY OF A. PALLIPES AND A. ITALICUS: GENETIC AND MORPHOMETRICAL INVESTIGATIONS

Genetic studies on the populations of Austropotamobius pallipes complex from Alessandria province (N-Italy), conducted on the basis of variations recorded in the sequences of mitochondrial DNA in the gene 16S RNA, have allowed to single out an overlapping zone of the distribution areas of the two taxa pallipes and italicus. In the crayfishes from a creek where both species have been ascertained to be present, the authors have applied the same molecular marker in order to investigate the distribution of the two taxa, stressing the syntopy of A. pallipes and A. italicus. Multivariate statistical techniques on 21 morphological parameters have been used in order to single out possible distinctive features of 31 crayfishes collected in this site, and of 225 crayfishes obtained from four sites in neighbouring areas. The results confirm the presence of a high morphological variability, not only at interspecific, but also at intraspecific level, which does not allow to distinguish the two species on the basis of the features measured in the present study.