Isler and Whitney • SPECIES LIMITS IN AN ANTBIRD COMPLEX 
9 
logically distinct neighbors. Populations separated 
by the Amazon River ( poecilinotus with grisei- 
ventris , nigrigula , and vidua ; duidae with guttur- 
alis and griseiventris ; and lepidonotus with 
gutturalis) were considered to be allopatric rather 
than parapatric as gene flow between them is 
highly unlikely. We provide brief summaries of 
morphological distinctions and consider biogeo¬ 
graphic relationships between neighboring pairs 
of parapatric subspecies starting with poecilinotus 
and duidae in the north and proceeding counter¬ 
clockwise around the Amazon Basin (localities 
provided in Fig. 1). 
Contact Between W. p. poecilinotus and W. 
p. duidae. —Females are distinguished by gray 
underparts in poecilinotus (brown in duidae) and 
buffy “scales” on the lower back of poecilinotus 
(white in duidae). Males differ only by a smaller 
interscapular patch in poecilinotus. Geographic 
ranges of poecilinotus and duidae are only 
partially delimited by rivers. The Rio Orinoco 
may separate the subspecies at the northernmost 
end of their contact zone. The most proximate 
specimen locations are from Cano Usate (COP, 
poecilinotus) and Campamento Manaka (COP, 
duidae ), Amazonas, Venezuela, —90 km apart. 
The Rio Orinoco lies between these locations as 
well as between Cano Usate and Colombian 
specimens from Vichada (Instituto Humboldt). 
Ranges of poecilinotus and duidae at the southern 
end of their contact zone in Amazonas, Brazil, 
extend to the left and right banks of the lower Rio 
Negro, respectively. Extensive fieldwork did not 
find either taxon on the many islands (Anavilha- 
nas Archipelago) in this broad river (Cintra et al. 
2007), although duidae occupies some islands in 
the upper Rio Negro near Sao Gabriel da 
Cachoeira. No barrier appears to prevent antbirds 
from coming into contact in the region between 
the upper Orinoco and the right bank of the Rio 
Branco; poecilinotus alone appears to occupy the 
area below the Rio Branco south to the Amazon. 
Apparent hybrids have been collected in the Valle 
de los Monos on the southern slope of Mt. Duida, 
Amazonas, Venezuela, where poecilinotus has 
been collected on the southeastern slope and 
duidae on the western slope. As described by 
Zimmer (1934) and corroborated by reexamination 
of the pertinent specimens by MLI, one (AMNH 
273015) of five females collected closely resem¬ 
bles duidae , one (AMNH 273017) is indistinguish¬ 
able from poecilinotus , and the remaining three 
(AMNH 273015, 273018, 273686) have a mixture 
of ventral and back scale coloration of the two 
populations. The most proximate locations to the 
southeast of Mt. Duida in Venezuela are Rio 
Putaco (COP, poecilinotus) and Ocamo (AMNH, 
duidae ), —100 km distant. Further southeast in 
Brazil, an even greater distance, —280 km, sepa¬ 
rates specimens from the Rio Dimiti in Amazonas 
and the vicinity of Caracarai, Roraima, although 
the intervening region is poorly studied omitho- 
logically. No hybrids other than those from Mt. 
Duida are known. 
Contact Be Ween W. p. duidae and W. p. 
lepidonotus. —Chapman (1923) described the 
duidae male as paler gray below, the female as 
more reddish and brighter throughout compared to 
lepidonotus. In addition, the interscapular patch 
was found to be smaller in duidae (Zimmer 1934). 
Chapman’s original description and Zimmer’s 
(1934) analysis were based on specimens from 
near the extremes of their ranges: Venezuela and 
northwestern Brazil for duidae and Peru and 
Ecuador for lepidonotus. Later Colombian spec¬ 
imens from along the base of the Andes in Meta 
were identified as duidae and those from western 
Caqueta and Putumayo as lepidonotus (Meyer de 
Schauensee 1964). Most recently, the population 
in the Sierra de Chiribiquete, Caquetd, Colombia, 
was identified as duidae (Stiles et al. 1995) which, 
along with the population in Tonantins, Amazo¬ 
nas, Brazil (CM), closes the gap between their 
ranges. However, a sufficient series of specimens 
from the intermediate region in Colombia has not 
yet been procured to examine possible clinality in 
morphological characters. 
Contact Between W. p. lepidonotus and W. p. 
griseiventris. —Females are distinguished by 
brown underparts in lepidonotus (gray in grisei¬ 
ventris) and white “scales” on the lower back of 
lepidonotus (absent in griseiventris). Males do not 
differ diagnosably. The Rio Ucayali separates the 
ranges of lepidonotus and griseiventris in central 
Peru. However, further south towards the head¬ 
waters of the Rio Ucayali, no river appears to 
perform this function. The closest confirmed 
locations are Kiteni; Cuzco (LSUMZ) for lepido¬ 
notus and the east slope of Cordillera de 
Pantiacolla, Madre de Dios (FMNH), for grisei¬ 
ventris. These locations are —190 km apart and 
are separated by mountainous terrain with eleva¬ 
tions >2,000 m. There are more proximate 
locations to the north in intervening terrain of 
lower elevation cited in the literature with 
unidentified subspecies. 
