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The Rusty-breasted Antpitta (Grallaricula ferrugineipectus) is widely distributed within the tropical Andes of South America. We analyzed 73 study specimens, 25 vouchered tissue samples, and 123 audio recordings to assess geographic variation in genetics, vocalizations, and morphology and evaluate species limits. We found that Grallaricula ferrugineipectus as currently defined is polyphyletic because populations from Colombia and Venezuela form a clade closely related to Andean populations of G. nana, whereas populations from Peru and Bolivia are recovered as sister to G. lineifrons. Birds in Colombia and Venezuela (the northern group) last shared a common ancestor with birds from Pera and Bolivia (the southern group) more than 10 million years ago. Northern and southern groups additionally differ in song, suggesting they may have evolved substantial premating reproductive isolation. Discriminant function analysis reliably distinguished songs from northern and southern groups in multivariate acoustic space, but univariate analyses found non-overlapping acoustic variation between northern and southern groups in only one trait: mean note maximum frequency (and other correlated measures of song pitch). This finding suggests that the 'three-trait' threshold for using vocalizations to inform species limits, which was developed for another suboscine group, the antbirds (Tharrmophilidae), may be conservative when applied to antpittas (Grallariidae). In addition, we document apparent clinal variation in song pace within the southern group, a rare example of a suboscine with geographic clinal variation in a vocal trait. Finally, we show that northern and southern groups differ markedly in morphology. In summary, northern and southern groups of Rusty-breasted Antpittas are divergent in genetics, vocalizations, and morphology, demonstrating that these taxa are best classified as 2 monophyletic, biological species with allopatric distributions. Received 3 August 2016. Accepted 22 May 2017. Key words: Andes, clinal variation, songs, South America, suboscine, taxonomy, vocalizations. Grallaricula ferrugineipectus es una especie ampliamente distribuida en los Andes tropicales de América del Sur. Con el fin de establecer los límites de especie, analizamos 73 especímenes, 25 muestras de tejido y 123 grabaciones de cantos que representan su variación geográfica genética, vocal y morfológica. Encontramos que Grallaricula ferrugineipectus es una especie polifilética porque las poblaciones de Colombia y Venezuela forman un ciado cercanamente emparentado con las poblaciones andinas de Grallaricula nana, mientras que las poblaciones de Perú y Bolivia son hermanas de Grallaricula lineifrons. Los individuos de Colombia y Venezuela (grupo del norte) compartieron un ancestro común con los individuos de Perú y Bolivia (grupo del sur) hasta hace más de 10 millones de años. Además, los grupos del norte y del sur se diferencian en su canto, lo que sugiere que ya surgió aislamiento reproductivo precigótico entre ellos. Un análisis de función de discriminantes pennitió distinguir los cantos de los grupos del norte y del sur en el espacio acústico multivariado. pero los análisis univariados sólo encontraron una variable cuya variación no se sobrepone entre grupos: frecuencia máxima promedio entre notas (y otras medidas del tono correlacionadas). Esto sugiere que el umbral de 'tres caracteres', usado para definir limites de especie en otro grupo de suboscinos (Thamnophilidae), puede ser conservador si se usa en los Gralláriidos. Adicionalmente, en el grupo del sur documentamos una aparente variación clinal en la cadencia del canto, hecho que representa un raro ejemplo de variación geográfica clinal en un carácter vocal en suboscinos. Finalmente, mostramos que los grupos del norte y del sur también difieren en morfología. En resumen, los grupos del norte y del sur son divergentes en genética, vocalizaciones y morfología, demostrando que deben ser tratados como dos especies biológicas monofiléticas con distribuciones alopátricas. Palabras clave: América del Sur, Andes, cantos, suboscinos, taxonomía, variación clinal, vocalizaciones., The Rusty-breasted Antpitta (Grallaricula ferrugineipectus) is a small antpitta in the family Grallariidae distributed from Venezuela to Bolivia, where it inhabits the understory of humid forests in the Andes and [...]

Results of a comprehensive molecular phylogeny of the family Thamnophilidae were consistent with earlier findings that almost all obligate army-ant-followers of the family form a monophyletic group that contains five well-supported clades and encompasses six currently recognized genera: Phaenostictus, Pithys, Willisomis, Gymnopithys, Rhegmatorhina, and Phlegopsis. A comparative analysis of seven suites of morphological, behavioral, and ecological traits within the context of the phylogeny reinforced the validity of five of these genera, but results for the sixth, Gymnopithys, were internally inconsistent and required the description of a new genus, Oneillornis. Received 22 November 2013. Accepted 5 July 2014. Key words: antbirds, Oneillornis, phylogeny, systematics, Thamnophilidae., Early naturalists in the Neotropics (e.g., Bates 1863) observed birds following army ants and capturing arthropods fleeing their onslaught. More recently, some of these species have been characterized as obligate [...]

The Ucayali River is a major tributary of the Amazon, but it narrows considerably toward its headwater at the base of the Andes. This region, the upper Ucayali Valley, is of biological interest for the large number of closely related birds elsewhere separated from each other by major rivers that come into close proximity and potential contact. Between 2006-2011, we conducted the first modern ornithological inventory of the upper Ucayali River and sampled localities in all major avian habitats on either side of the river. We document the continued importance of the Ucayali River as a biogeographic barrier, even at the headwater, but also find that some mixing occurs, both in the form of taxa crossing to the 'wrong' bank and in the potential intergradation of distinct forms. We describe the biogeography of birds in the region, characterize the avifaunas of major habitats, and discuss in detail species of particular biogeographical interest. Received 25 August 2013. Accepted 10 January 2014. Key words: Amazonia, biogeography, range extension, river barrier, river island, Ucayali, white sand., The rivers of the Amazon Basin are important barriers to the distributions of terrestrial animals (Wallace 1852), even for relatively vagile taxa such as birds (Sick 1967, Haffer 1969). The [...]