Phylogenetic relationship among slender loris species (Primates, Lorisidae: Loris) in Sri Lanka based on mtDNA CO1 barcoding

There are 2 species of slender lorises found in Sri Lanka: the red slender loris, Loris tardigradus (Linnaeus, 1758), endemic to the wet zone and montane areas, and the grey slender loris, Loris lydekkerianus (Cabrera, 1908), which is widespread. In addition, currently there are 2 subspecies recognized for each of these 2 slender loris species of Sri Lanka. Yet their taxonomy, evolutionary history, and biogeography are still poorly understood, and there are some preliminary data suggesting the presence of other subspecies. In this study, we have analysed the partial mitochondrial cytochrome oxidase I gene sequence of 21 Loris specimens collected from 7 different regions in Sri Lanka. The phylogenetic tree reconstructed based on the neighbour joining method and Bayesian approach revealed 2 clades with high branch supports (>60%), consistent with the 2 slender loris species. Moreover, the samples within the Loris lydekkerianus clade were divided into 3 taxa and the samples within the Loris tardigradus clade were divided into 4 taxa, all consistent with the 7 sampling zones. The results of the study have provided the first DNA barcoding analysis on slender lorises in Sri Lanka to resolve phylogenetic relationships. Further studies on Loris are necessary for decoding their taxonomic issues in Sri Lanka.