Phylogenetic Relationships of the Zigzag Heron (zebrilus Undulatus) and White-crested Bittern (tigriornis Leucolophus) Estimated by Dna-dna Hybridization

ASSTRACT.--Recently, we acquired DNA of two rare species of heron, the Neotropical Zigzag Heron (Zebrilus undulatus) and the African White-crested Bittern (Tigriornis leucolophus). To estimate their phylogenetic relationships to other herons, we compared these species with representatives of the major heron clades using DNA-DNA hybridization. Even though the Zigzag Heron resembles a tiger-heron in its barred plumage and forest habitat, it is most closely related to bitterns. The White-crested Bittern is monophyletic with the New World tiger-herons (Tigrisoma) and, thus, is better termed the White-crested Tiger-Heron. These findings accord well with phylogenetic analyses based on osteology. The remaining uncertainties in higher-level heron phylogeny are principally: (1) the position and composition of some enigmatic genera (e.g. Gorsachius, Agamia, Pilherodius, and Ardeola); and (2) the identification of the basal heron lineage, which appears to be either tiger-herons or the Boatbilled Heron (Cochlearius). Received 15 June 1994, accepted 27 January 1995.