This is primarily because
the three taxa are regarded as distinct species, each occupying
different distributions within the region: B. dorsalis
s.s. around the northern edge (north of the Thai/
Malay peninsula), B. papayae around the western and
southern edge (Thai/Malay peninsula and into the Indonesian
archipelago) and B. philippinensis at the eastern
edge (the Philippines and Borneo) (Figure 1