A taxonomic review of Aramides cajaneus (Aves, Gruiformes, Rallidae) with notes on morphological variation in other species of the genus

Abstract

The taxonomy of the polytypic and wide-ranging Gray-necked Wood-rail, Aramides cajaneus is reviewed, based on external morphology and voice. Throughout its distribution, there is extensive plumage variation, much of it taxonomically uninformative. However, through three informative plumage characters, as well as morphometric and vocal variation, three phylogenetic species were identified within what is today known as A. cajaneus, all of which already had available names: A. albiventris Lawrence, 1868, from southern Mexico to northeastern Costa Rica, A. cajaneus (Statius Müller, 1776) (sensu stricto), from southwestern Costa Rica to Argentina, and A. avicenniae Stotz, 1992, from a small section of the coast of southeastern Brazil. A. albiventris presents extensive plumage variation, but with no geographic structure. The song of A. cajaneus and A. avicenniae is strikingly and completely different from the song of A. albiventris. A previously unnoticed parapatric pattern of distribution of A. cajaneus and its congener A. saracura in southeastern Brazil is described, and we clarify that the name A. plumbeicollis, included in the synonymy of A. albiventris, was first made available in 1892, rather than in 1888 as is widely referred. In addition, plumage variation in A. ypecaha, A. wolfi, and A. mangle is discussed.