PHYLOGENETIC RELATIONSHIPS OF ANTPITTA GENERA (PASSERIFORMES: FORMICARIIDAE)

Auk, The, Apr 2005 by Rice, Nathan H

ABSTRACT

Phylogenetic relationships among the antpitta genera were studied using DNA sequence data from the mitochondrial genome. The clade representing the traditional "antpitta" genera (Grallaria, Grallaricula, Hylopezus, Myrmothera, and Pittasoma) was found to be paraphyletic, owing to the sister relationship of Pittasoma and Conopophaga. In a previously unreported relationship, Pittasoma was strongly supported as the sister genus to Conopophaga (Conopophagidae). The remaining antpitta genera form a fully resolved and well-supported monophyletic lineage with two major subclades. The first clade consists of the genus Grallaria and supports the subgenera identified by Lowery and O'Neill (1969). The second antpitta clade has Hylopezus as the sister genus to Myrmothera, with Grallaricula as their sister genus. The results here allow for a new interpretation of the morphological characters used in previous studies. Received 14 July 2004, accepted 13 December 2004.

Key words: antpitta, Conopophaga, phylogeny, Pittasoma.

Relaciones Filogenéticas de los Géneros de Tororoíes

RESUMEN. - Las relaciones filogenéticas entre los géneros de tororoies ("antpittas" en inglés) se estudiaron con base en datos de secuencias del ADN del genoma mitocondrial. Se encontró que el clado que representa a los géneros tradicionalmente considerados en el grupo (Grallaria, Grallaricula, Hylopezus, Myrmothera y Pittasoma) es parafilético, debido a que Pittasoma y Conopophaga (Conopophagidae) son géneros hermanos, una relación fuertemente apoyada que no había sido documentada previamente. El resto de los géneros de tororoíes forman un linaje monofilético totalmente resuelto y bien apoyado, que contiene dos subclados principales. El primer clado consiste del género Grallaria y apoya los subgéneros identificados por Lowery y O'Neill (1969). El segundo clado tiene a Hylopezus como el género hermano de Myrmothera, y Grallaricula como el género hermano de ambos. Los resultados de este trabajo permiten una nueva interpretación de los caracteres morfológicos utilizados en estudios previos.

GROUND ANTBIRDS (FORMICARIIDAE) form a diverse clade (~60 species) of suboscine passerines found exclusively in the Neotropics. Formicariids are plainly colored but attractively patterned birds that hop or walk on or near the ground. Because of their cryptic coloration and secretive habits, ground antbirds are more often heard than seen. The Formicariidae has not been the subject of any detailed phylogenetic study, with most published and ongoing research focused on alpha taxonomy and documentation of natural history (e.g. Graves 1987, Stiles 1992, Kratter 1995, Krabbe et al. 1999, Barber and Robbins 2002).

The most speciose group within the Formicariidae is the antpittas (Grallaria, Grallaricula, Hylopezus, Myrmothera, and Pittasoma). Antpittas come in an impressive range of body sizes and live in a variety of habitats in the Neotropics. Antpittas have disproportionately long legs, compared with their body size and short tails. The nests of only a few species have been described-generally sloppily constructed cups or saucers of sticks and leaves lined with root-lets or moss and placed 1-2 m above the ground (Wiedenfeld 1982). Antpittas reach maximum species diversity in the Andes, where they show marked altitudinal species replacements (Graves 1987). As access to remote areas in the Neotropics has increased and equipment for avian survey work has improved, numerous new antpitta species have been described (Lowery and O'Neill 1969, Schulenberg and Williams 1982, Graves 1987, Stiles 1992, Krabbe et al. 1999). However, no previous study has examined the phylogenetic history of the group. Here, I (1) reconstruct the evolutionary relationships of antpittas and (2) examine the evolution of selected morphological and vocal characters in a phylogenetic context.

History of antpitta taxonomy. - Ridgway (1911) followed Sclater (1890) in placing the antpittas as a subfamily of the Formicariidae (the Grallarinae), but expanded the subfamily to include eight genera: Rhopoterpe, Pittasoma, Grallaricula, Grallaria, Hypsibemon, Oropezus, Myrmothera, and Hylopezus. Ridgway (1911) added bill morphology, presence of rictal bristles, and tarsal scutellation to the characters used by Sclater (1890) to diagnose those genera. Cory and Hellmayr (1924) recognized six genera of antpittas in their subfamily Myrmotherinae (Myrmornis, Pittasoma, Grallaricula, Thamnocharis, Myrmothera, and Grallaria), but offered little explicit character support. Incongruously, Myrmothera was separated from Grallaria and Thamnocharis on the basis of the absence of rictal bristles; but Hylopezus, which also lacks rictal bristles, was included in Grallaria (Cory and Hellmayr 1924). That scheme was followed by Peters (1951), with the exception of the subfamilial divisions.

On the basis of plumage characteristics, skeletal characters, and morphometric measurements, Lowery and O'Neill (1969) revised the subfamily Grallarinae to near its current composition by including five antbird genera: Grallaria, Grallaricula, Hylopezus, Myrmothera, and Pittasoma. Grallaria was further divided into four subgenera (Grallaria, Thamnocharis, Oropezus, and Hypsibemon). The notion of previous authors (Sclater 1890, Ridgway 1911, Cory and Hellmayr 1924, Peters 1951) that Hylopezus, Myrmothera, and Grallaricula were congeneric with Grallaria was disputed.