Phylogenetic history of the Sifakas ( Propithecus: Lemuriformes) derived from cytogenetic studies.

The R-banded karyotypes of the different subspecies of Propithecus diadema and P. verreauxi are compared to each other and to that of P. tattersalli, as well as those previously reported of Indri indri and Avahi laniger. This comparison shows that the different subspecies of P. verreauxi possess the same karyotype and that, among P. diadema, P. d. diadema and P. d. perrieri share the same karyotype differing from that of P. d. edwardsi by one Robertsonian translocation. The karyotype of P. tattersalli differs at least through 17 and 9 rearrangements from those of P. diadema and P. verreauxi, respectively. This provides strong arguments in favor of its specific status. The phylogenetic diagram proposed confirms the early separation of Avahi and the relatively late divergence of the four other species. A populational evolution has occurred between these four species, P. tattersalli and P. verreauxi sharing the largest number of rearrangements (six), while the numbers of rearrangements shared by the other species are two for Indri and P. verreauxi, three for P. tattersalli and Indri, and three for P. tattersalli and P. diadema. No branch is common to two species of Propithecus.