Wakatobi sunbird
The Wakatobi sunbird (Cinnyris infrenatus) is a species of sunbird endemic to the central Indonesian Wakatobi islands, at times restricted from tiny Wakatobi islands, off the southeastern coast of the larger Sulawesi. C. infrenatus has a higher pitched voice, darker plumage and shorter wings compared to the olive-backed sunbird (Cinnyris jugularis), to which it is closely related. The speciation of the olive-backed and Wakatobi sunbirds follows Alfred Wallace's prediction about the Wallace Line, a separation of deep and shallow oceans of Asia and Australia that is difficult for most species to cross. Even more difficult when pressures from deforestation continue to increase, making it harder for these species to develop. O'Connell et al. (2019a) observed that Wakatobi infrenatus sunbirds showed stronger sexual dimorphism and a larger population density in comparison to plateni birds from Sulawesi and the land-bridge islands, confirming the physical and ecological differences between the two species. References 

infrenatus
Endemic birds of Sulawesi
Birds described in 1903