Phylogeny of the slow lorises (genusNycticebus): An approach using mitochondrial DNA restriction enzyme analysis

Mitochondrial DNA polymorphisms in 15 specimens of three species of slow lorises-Nycticebus coucang, N. intermedius, andN. pygmaeus-were analyzed in order to study the evolutionary relationships among the species. Eight restriction types were observed in the samples. Phylogenetic trees constructed on the basis of genetic distances showed that the slow lorises sort into two clusters: four types ofN. coucang and three types ofN. intermedius plus one type ofN. pygmaeus. Our results suggest that there are two valid species in the genusNycticebus-N. coucang, andN. pygmaeus-and thatN. intermedius should be included withinN. pygmaeus. Divergence between the two species may have begun 2.7 Ma (million years ago). Evolution of gross morphology, chromosomes, and mitochondrial DNA in the slow lorises appears to be concordant.