The origin and phylogenetic relationships of the New Zealand ravens

Abstract

The relationships of the extinct New Zealand ravens (Corvus sp.) are poorly understood. We sequenced the mitogenomes of the two currently recognised species and found they were sister-taxa to a clade comprising the Australian raven, little raven, and forest raven (C.coronoides, C. mellori and C. tasmanicus respectively). The divergence between the New Zealand ravens and Australian raven clade occurred in the latest Pliocene, which coincides with the onset of glacial deforestation. We also found that the divergence between the two putative New Zealand species C. antipodum and C. moriorum probably occurred in the late Pleistocene making their separation as species untenable. Consequently, we consider Palaeocorax antipodum Forbes, 1893 to be a subspecies of Corvus moriorum Forbes, 1892. We re-examine the osteological evidence that led 19(th) century researchers to assign the New Zealand taxa to a separate genus, and re-assess these features in light of our new phylogenetic hypotheses. Like previous researchers, we conclude that the morphology of the palate of C. moriorum is unique among the genus Corvus, and suggest this may be due to their reliance during the Holocene on a specialist diet.