Grallaria occabambae ( Chapman, 1923 )

Isler, Morton L., Chesser, Terry, Robbins, Mark B., Cuervo, Andrés M., Cadena, Carlos Daniel & Hosner, Peter A., 2020, Taxonomic evaluation of the Grallaria rufula (Rufous Antpitta) complex (Aves: Passeriformes: Grallariidae) distinguishes sixteen species, Zootaxa 4817 (1), pp. 1-74 : 22-23

Grallaria occabambae ( Chapman, 1923) , subspecies elevated to species

Urubamba Antpitta

Includes populations designated occabambae 1a and occabambae 1b in the analysis.

Diagnosis. Nominate form upperparts dark reddish yellow-brown; underparts lighter with pale feather edgings; undertail coverts pale yellowish-buff. Short songs of two (G. o. occabambae ) ( Fig. 15 ) or three ( G. occabambae marcapatensis ) ( Fig. 16 ) unmodulated notes distinguish G. occabambae from all but the two-noted short songs of G. cochabambae and G. sinaensis . Short song notes of G. occabambae differ from those of G. cochabambae and G. sinaensis in being rounded (as opposed to flat and slightly downslurred) and by longer notes and internote intervals. Long songs of G. occabambae differ from those of G. cochabambae and G. sinaensis in having inverted U-shaped notes (as opposed to flat or downslurred notes), in having internote intervals lengthening (as opposed to lengthening, stabilizing, and shortening) resulting in decelerating pace, and in having a flat or slowly declining peak frequency pattern (as opposed to peaks decreasing, stabilizing, and increasing); also apparently in overall pace, although small sample sizes limit diagnosability.

Distribution. Endemic to Peru in extreme eastern Junín (Cordillera Vilcabamba) and Cusco east of the Río Ene and Río Apurímac and between the Río Tambo to the north and the Río Marcapata to the south, 2450–3650 m. Two subspecies; nominate subspecies occurs west of the Río Yanatili valley, Cusco.

Plumage. Overall plumage of upperparts, including rectrices, remiges (primaries edged paler), crown and auriculars, typically dark reddish-yellow-brown (7.5YR 4/4) but variable, tending toward browner (5YR 4/4) in nominate form and lighter and brighter (7.5YR 5/6) in G. o. marcapatensis; malar tending to color of breast. Throat, breast and belly light reddish yellow-brown (7.5YR 6/8) with pale feather edgings. Undertail coverts pale yellowish-buff (2.5Y 8/4) in nominate form and light reddish-yellow-brown (7.5YR 7/8) in G. o. marcapatensis (specimen photographs App. 6, Figs. A29 and A30).

Etymology. The English name is adapted from Cory & Hellmayr (1924).

Remarks. The distinction in number of notes in short songs indicates that occabambae 1a and occabambae 1b should be considered subspecifically distinct, and a new subspecies is described below. Compared to neighboring taxa, plumage of G. occabambae is paler and separable from that of Grallaria centralis and G. ayacuchensis , but similarly colored G. gravesi , G. obscura and G. sinaensis appear to be distinguished from G. occabambae only by the greater extent of pale edgings on the breast feathers of G. occabambae , a character requiring confirmation in large samples. Nominate form includes occabambae 1a. It appears that the Río Yanatili valley separates ranges of subspecies of G. occabambae . The phylogeny ( Chesser et al. 2020) includes in occabambae 1b a specimen (MSB 168436) collected on a mountain bordering the Río Yanatili to the east, and the type locality of G. rufula occabambae is the Occabamba Valley = Río Ocobamba, which is a western tributary of the Río Yanatili ( Stephens & Traylor 1983). Recordings from the upper reaches of this river are of occabambae 1a.

Figures

FIGURE 15. Songs of Grallaria o. occabambae: (A) long song, Carrizales, Cusco, Peru (Lane ML236893); (B) short song, San Luis, Cusco (Krabbe XC47645).

FIGURE 16. Songs of Grallaria occabambae marcapatensis: (A) long song, Abra Acjanaco, Cusco, Peru (Lane ML236892); (B) short song, upper Manu Road, Cusco (Lane ML236891).