Proposal (486) to South American Classification Committee
Restore the genus Microxenops for Xenops milleri
In naming the new genus Microxenops, Chapman (Chapman 1914) commented “Doubtless it resembles Xenops in habits, as it does in general appearance, but the marked difference in their structure suggests that the resemblance is superficial rather than indicative of close relationship.”
Chapman was correct. Two molecular studies, Moyle et al. (Moyle et al. 2009) and Derryberry et al. (in press) demonstrate conclusively that Xenops milleri is not closely related to the clade containing all other Xenops. X. milleri occurs as a long branch that is sister to a clade containing Pygarrhichas and Ochetorhynchus. The other Xenops occur as the basal clade to all other furnariids.
I propose restoring the genus Microxenops for Xenops milleri.
Derryberry, E. P., S. Claramunt, G. Derryberry, R. T. Chesser, J. Cracraft, A. Aleixo, J. Pérez-Emán, J. V. Remsen Jr., and R. T. Brumfield. in press. Lineage diversification and morphological evolution in a large-scale continental radiation: the Neotropical ovenbirds and woodcreepers (Aves: Furnariidae). Evolution.
Moyle, R. G., R. T. Chesser, R. T. Brumfield, J. G. Tello, D. J. Marchese, and J. Cracraft. 2009. Phylogeny and phylogenetic classification of the antbirds, ovenbirds, woodcreepers, and allies (Aves: Passeriformes: infraorder Furnariides). Cladistics 25:386-405.
Robb Brumfield, June 2011
Comments from Remsen: “YES. This is another one of those Peters Era lumps that never should have happened. As noted in my HBW chapter, the only thing this bird shares with true Xenops is the wing band – it lacks the distinctive tail pattern, the conspicuous malar mark, the laterally compressed bill, and the dead-twig-hammering behavior of Xenops.”
Comments from Stiles: “YES. I agree that milleri is certainly an oddball in Xenops; a monotypic genus emphasizes its distinctness.”
Comments from Nores: “YES. For reasons succinctly laid out in the proposal, it is evident that Xenops milleri is not closely related to the clade containing all other Xenops.”
Comments from Pacheco: “YES. O restabelecimento de Microxenops prova ser uma apropriada medida.”
Comments from Zimmer: “YES. Two sets of molecular data now provide evidence corroborating what many of us have felt all along regarding not only morphological differences between milleri and the rest of Xenops, but also vocal differences, which are perhaps even greater.”
Comments from Pérez-Emán: “YES. This taxon is clearly different from Xenops both in molecular and morphological grounds.”