- 
10 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
Contact Between W. p. gutturalis and W. p. 
griseiventris. —Females are distinguished by 
brown underparts in gutturalis (gray in griseiven¬ 
tris) and white “scales” on the lower back of 
gutturalis (absent in griseiventris). Females of 
gutturalis also typically have crown redder than 
back (concolor in other populations). Males of 
gutturalis have black throat patches (absent in 
griseiventris). The geographic range of gutturalis 
is the smallest of any subspecies, restricted in 
Peru and Brazil to the region immediately south of 
the Amazon and east of the lower Rio Ucayali 
(Fig. 1). The extent of its range to the east and 
south is unclear. The likelihood that the Rio J urua 
provides a barrier in a section of their contact 
zone is supported by specimens of female 
gutturalis from Eirunepe (formerly Joao Pessoa) 
on the left bank of the Jurua and by male 
griseiventris from Santa Cruz on the Rio Eiru, a 
right bank tributary (Pinto 1942, 1978; specimens 
examined at MZUSP). However, sight records 
from both banks of the Rio Jurua at the Reserva 
Uakarai were identified as griseiventris (Andrew 
Whittaker, pers. comm.). To the southwest, in the 
Jurua-Ucayali interfluvium, griseiventris has 
been found at Divisor, Loreto, Peru, and at two 
other locations west of the Sierra del Divisor 
(Vriesendorp et al. 2006:195). Consequently, 
known ranges of gutturalis and griseiventris are 
separated by ~280 km of probably suitable 
habitat in this region with no river barriers. 
Contact Between W. p. griseiventris and W. 
p. nigrigula. —The extension of the gray of the 
underpails to the sides of the head (ear coverts and 
lores) distinguishes female nigrigula from grisei¬ 
ventris. Males of nigrigula have a black throat, 
while throats of male griseiventris are plain gray. 
The Rio Canuma and, continuing further up¬ 
stream, the Rio Sucunduri, separates their ranges 
(regions of locations 22 and 24; Fig. 1). However, 
the range of griseiventris passes the headwaters of 
the Rio Sucunduri to reach the Rio Tapajos above 
Jacareacanga, where it overlaps nigrigula and 
may hybridize with it locally (BMW observations 
and recordings of both taxa). Beyond this point, to 
the south, only griseiventris has been found on the 
left (west) bank of the Rio Tapajos and its major 
tributary, the Rio Teles Pires, whereas nigrigula 
occurs on the right (east) bank of these rivers. 
Contact Between W. p. nigrigula and W. 
p. vidua .—Males of nigrigula have discreet black 
throat patches which are absent in vidua , the 
throat of which tends to be more whitish than its 
gray underparts. Females of vidua differ from 
nigrigula by having flanks suffused reddish- 
yellow-brown (slightly tinged in nigrigula) and 
wing edgings grayish-brown (reddish-yellow- 
brown in nigrigula). Interscapular patches are 
larger in nigrigula (15-20 mm) than in vidua (0- 
10 mm). The known geographic ranges of 
nigrigula and vidua with one exception are 
separated by a wide geographic gap west of the 
Rio Xingu (Fig. 1), although much of the region 
between the known ranges of these populations is 
unexplored ornithologically. The only known 
convergence of nigrigula and vidua is based on 
sight records by BMW in September 1994 of 
males within ~1 km of each other at Riozinho, 
Area Indigena Kayapo, Para; it cannot be 
considered definitive, but does serve to suggest 
the possibility of parapatry of these forms in this 
poorly studied region. 
DISCUSSION 
Diagnostic differences in loudsongs, raspy 
series, and contact calls were documented be¬ 
tween two groups of taxa that were also distinct in 
plumage: nigrigula and vidua of southeast Ama¬ 
zonia, and the remaining populations. However, 
compared to other widespread Amazonian tham- 
nophilid complexes studied by the authors (e.g., 
Isler et al. 2007a, b), relatively few vocal 
differences meeting our guidelines for species 
status were found among other populations in the 
Willisornis complex. Consequently, we recom¬ 
mend the complex be considered to consist of two 
species and seven subspecies: 
Willisornis poecilinotus (Cabanis)—Common 
Scale-backed Antbird 
W. p. poecilinotus (Cabanis) 
W. p. duidae (Chapman) 
W. p. lepidonotus (Sclater and Salvin) 
W. p. griseiventris (von Pelzeln) 
W. p. gutturalis (Todd) 
Willisornis vidua (Hellmayr)—Xingu Scale- 
backed Antbird 
W. v. nigrigula (Snethlage) 
W. v. vidua (Hellmayr) 
The proposed English name of W. vidua is taken 
from the major river that flows through the center 
of its geographic range. 
Within each of these two groups, differences in 
