Cytological and molecular analysis in the rare discoglossid species, Alytes muletensis(Sanchiz & Adrover 1977) and its bearing on archaeobatrachian phylogeny

Cytogenetic and molecular data on Alytes muletensis(Amphibia: Discoglossidae) are compared with other representatives of archaeobatrachian frogs: Bombina variegata pachypus, Pelobates cultripes, Pelodytes punctatus, Xenopus laevis, and Discoglossus. A. muletensishas the karyotype typical for the genus Alytes, 38 elements with either one or two arms, some of which can be considered as ‘microchromosomes’. The NORs are located on the telomeres of the tenth chromosome pair which agrees with the state in A. obstetriciansbut differs from A. cisternasiireflecting phylogenetic affinities. C-banding and staining with DAPI and chromomycin A3revealed important blocks of telomeric CMA-positive heterochromatin on the smaller chromosomes of Alytes, similar to the state found in Discoglossus. Phylogenetic analysis of 750 bp of fragments of the mitochondrial 16S and 12S rRNA genes corroborated that Discoglossusand Alytesare sister taxa which together probably form the sister group of the Bombinatorinae. Centromeric heterochromatin in Alytesmay be responsible for the retention of a plesiomorphic asymmetric karyotype which independently has evolved into a symmetric karyotype through centric fusions in Bombinaand Discoglossus. The HindIII satellite DNA family was present in all archaeobatrachians studied but absent in hyloid and ranoid neobatrachians.