 The bird's cranial osteology, myology, plumage, and bill morphology confirmed the distinctness of the species.The hookbill was a member of the Hawaiian honeycreeper subfamily Drepanididae and the tribe Psittirostrini, which it shared with seven historically recorded species and about ten species known only from fossils.It is believed that the Lānai hookbill was most closely related to the ōū .