It seems probable that there are more species (in the sense of sharply diagnosable entities) than hitherto recognized among small Asian primates, and contrasting to some degree with larger-sized taxa. This presumably relates to their lesser vagility and consequent reduced potential for gene-flow. Even where some gene-flow can be demonstrated, as betweenNycticebus coucang andN. bengalensis, this appears to be very limited and does not affect the essential homogeneity and diagnosability of the two taxa.
The biogeographic implications of the taxonomic findings of this study are noteworthy. They confirm the distinctness of Sulawesi in contrast to a Sundaland/southern Philippines link (Tarsius); the separation of the Indochinese and Sundaic faunal subregions (Nycticebus); and the uniqueness of the Sri Lankan “wet zone” (Loris). Much more work needs to be done on all three genera, but their great taxonomic interest, indicating much greater complexity than previously assumed, is apparent.