Molecular Systematic Analyses of Mediterranean Skates (Rajiformes)

Mitochondrial 16S ribosomal RNA was used to elucidate the pattern of relationships and systematic status of 4 genera, including 9 species of skates (Rostroraja alba, Leucoraja fullonica, Dipturus oxyrinchus, D. batis, Raja clavata, R. montagui, R. asterias, R. miraletus, and R. radula), living in the Mediterranean and Black Seas. The 16S rDNA dataset contained 39 variable and 29 parsimony informative sites. The mean nucleotide diversity (Pi) was 0.018. The genetic distances between pairs of species showed genetic homogeneity between R. clavata and R. montagui. The highest value of sequence divergence was detected between D. oxyrinchus and R. asterias (0.040). Low genetic distances were shown by the comparisons of R. montagui with R. miraletus and of R. clavata with R. miraletus. The phylogenetic tree revealed 4 main evolutionary lineages; the first lineage included R. clavata, R. montagui, and R. miraletus. L. fullonica was clustered with R. asterias in the second lineage. In the third lineage, D. batis and D. oxyrinchus showed a close relationship, which was the sister group to R. radula. R. alba was clustered separately from all others.