× Archaeolacerta bedriagae (Camerano, 1885) is a rock lizard endemic to Corsica and Sardinia. Based on weak morphological traits four subspecies have been described to date. The nominal subspecies (A. b. bedriagae) occurs on Corsica. The three following subspecies inhabit different geographic areas of Sardinia: A. b. sardoa (Gennargentu Massif), A. b. paessleri (Limbara Mountains), A. b. ferrerae (coastal Gallura). Allozyme variation in A. bedriagae was previously investigated by Guillame and Lanza (1982). These authors compared three populations only (one from Corsica and two from Sardinia) and obtained very high values of Nei’s genetic distance, ranging from 0.172 to 0.309. However, the values of genetic distance indicated by those authors were completely wrong because of miscalculation. On a subsequent paper Guillame (1987) proposed a different genetic scenario, indicating corrected values of Nei’s genetic distance among the three A. bedriagae populations, ranging from 0.133 to 0.186. These values, although being much lower than those estimated by Guillame and Lanza, are in fact very high, falling into the range obtained from comparisons between well recognized biological species of the genera Lacerta and Podarcis. In spite of this, Guillaume (1987) proposed to synonymised two subspecies (A. b. paessleri and A. b. ferrerae), and Lanza (1983) questioned the systematic validity of the Sardinian subspecies. On the other hand, based on the genetic data reported by Guillame and Lanza, Arribas (1999) hypothesized the occurrence of unrecognized species of the genus Archaeolacerta within the Corso-Sardinian area. In addition, in a paper devoted to the systematics of the tribe Lacertini, Arnold et al. (2007) found considerable mitochondrial DNA variation among three Corsican individuals of A. bedriagae, and hypothesized the occurrence of more than one species.
In this paper allozyme variation of A. bedriagae was studied, and the results were compared with those obtained in previous studies. A total of 55 individuals from 5 Corsican (Roccapina) and Sardinian (Punta Falcone, Limbara Mountains, Gennargentu Massif, Mount Settefratelli) localities were used. All recognized subspecies were included in the analysis, plus one sample from southern Sardinia (Mount Settefratelli) for which the recognition of the subspecific status was suggested. For interspecific comparison, 11 individuals of Iberolacerta cyreni (Müller & Hellmich 1937) from Central Spain (Sierra de Guadarrama) were also analyzed. Approximately 2 cm of the tail tip of each lizard was taken off, in order to avoid killing animals, and stored below -70°C until electrophoretic analysis. Standard horizontal starch gel electrophoresis was performed on muscle tissue homogenates using buffer systems and procedures described by Capula. Gene products for the following 20 presumptive gene loci were analaysed,: αGpd, Ldh-1, Ldh-2, Mdh-1, Mdh-2, Me-1, Me-2, Idh-1, Idh-2, 6Pgd, Sod-1, Ak, Pgm-1, Pgm-2, Ck, Mpi, Gpi, Est-1, Gp-1, Gp-2. Genotype and allele frequencies were determined by direct count from allozyme phenotypes. The genetic relationships among the populations studied were evaluated using Nei’s standard genetic distance (D). The phenetic relationships among populations were estimated by means of the UPGMA method.
Eleven out of 20 loci were found to be monomorphic, i.e. fixed for the same allele, in all populations (αGpd, Ldh-2, Mdh-1, Mdh-2, Idh-2, Sod-1, Ak, Pgm-1, Pgm-2, Gp-1, Gp-2). Three out of nine polymorphic loci were weakly polymorphic (Ldh-1, Me-2, Mpi). Lizards from Corsica were characterized by two unique alleles, i.e. Mpi102 and 6Pgd95. Four unique alleles were found in the Sardinian populations: Est-1102 in all populations, Me-295 in the population from the Limbara Mountains, 6Pgd105 and Ldh-195 in the populations from the Mount Settefratelli. Low levels of genetic differentiation were found in A. bedriagae, Nei’s D ranging from 0.013 to 0.042, with an average genetic distance of 0.026 (SD = 0.010). A similar value of Nei’s D was found between Corsican and Sardinian populations (D = 0.025; SD = 0.008). The sample from the Mount Settefratelli (southern Sardinia) was considerably differentiated from the other ones (average D = 0.032; SD = 0.011). Low Nei’s genetic distance values were found comparing the four recognized subspecies (average D = 0.023; SD = 0.007). Our results are not in accordance neither with those reported by Guillame and Lanza, nor with those by Guillame (1987), clearly indicating low levels of genetic differentiation among populations. Genetic differentiation among the recognized subspecies resulted to be much lower than the one estimated by Guillame and Lanza (1982). Our results are in agreement with the mitochondrial DNA analyses, the nuclear markers analyses and the morphometric analyses. This would indicate that the supposed occurrence of a unrecognized Archaeolacerta species within the Corso-Sardinian Plate is not supported by genetic data.