The most abundant reef fish at Rangitāhua (Kermadec Islands) is a species of Chrysiptera, formerly classified as Chrysiptera rapanui. Combined morphological and genetic evidence supports two endemic species: C. rapanui confined to Rapa Nui (Easter Island) and a new species of Chrysiptera confined to the islands of Rangitāhua. We present the evidence to separate the two species, and the relationships to other species of Chrysiptera in the South Pacific region. Ngāti Kuri, the iwi (Māori tribe) that are kaitiaki (caretakers) of Rangitāhua, contributed to the indigenous naming of this species. We present the collaborative process in working with iwi in naming new species and the limits of the International Code of Zoological Nomenclature in acknowledging the authority of indigenous tribes and matauranga Māori (indigenous knowledge).