Grallaria gravesi Isler, Chesser, Robbins & Hosner, 2020

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 : 17-18

Grallaria gravesi Isler, Chesser, Robbins & Hosner , new species

Graves’s Antpitta

Includes population designated obscura 1 in the analysis.

Diagnosis. Upperparts dark reddish yellow-brown; underparts paler, palest on belly and undertail coverts; pale buff eye-ring. Both long songs and short songs are distinguished from those of all other populations except G. oneilli and G. obscura by their frequency modulated notes, delivered in a series in long songs and in pairs in short songs ( Fig. 10 ). The pace of long songs of G. gravesi is faster than that of G. obscura but slower than that of G. oneilli . Intervals between notes of the long song of G. gravesi increase and then decrease in duration, whereas intervals of the G. oneilli long song remain nearly constant, and those of G. obscura increase in duration throughout. Two additional characters distinguish vocalizations of G. gravesi from G. obscura although not from G. oneilli . Notes in the second half of long songs of G. gravesi and G. oneilli rise in frequency, whereas those of G. obscura decline. In addition, initial notes of short songs of G. gravesi and G. oneilli come to a single frequency peak, whereas initial notes of G. obscura include three peaks (rarely two).

Distribution. Endemic to Peru on east Andean slope in Amazonas and San Martín south and east of the Río Marañón, south to Huánuco north of Río Huallaga, 2400–3900 m.

Holotype. Louisiana State University Museum of Natural Science ( LSUMZ) 104488, tissue number LSUMZ B–809. Adult female mist-netted in isolated patch of temperate forest and prepared by S. Allen-Stotz on 5 August 1981 at Puerto del Monte, ca. 30 km NE Los Alisos, San Martín, Peru (approximately 77° 28’ W, 07° 32’ S, elevation 3250 m).

Description of holotype. Adult female. Overall plumage of upperparts, including crown, auriculars, nape, back, and uppertail coverts, dark reddish yellow-brown (7.5YR 4/4), shading to underparts color in malar area; eyering pale buff. Rectrices and remiges dark reddish yellow-brown (7.5YR 4/4), primaries edged paler. Throat and breast reddish yellow-brown (7.5YR 5/8), paler on belly and undertail coverts with center of belly whitish; flank coloration intermediate between upperparts and breast. Soft part colors: iris brown, bill slate, tarsi/feet blue-gray. Ovarian mass 5 x 4 mm; skull ossified; mass 33.2 g; insect parts in stomach.

Measurements of holotype. Bill length 10.58 mm, bill width 4.77 mm, wing length 81.66 mm, tail length 45.40 mm, tarsus length 41.69 mm.

Paratopotype. LSUMZ 104491 (female).

Paratypes. LSUMZ 74099 (male) , LSUMZ 74104 (female) , ANSP 176470 (male) , FMNH 296697 (female) (specimen photographs App. 6, Fig. A 24) .

Etymology. We are pleased to name this species for our friend and colleague Dr. Gary R. Graves, whose ornithological contributions include the field work and subsequent analysis that resulted in the recognition of G. blakei . After describing G. blakei, Gary Graves embarked on a study of the taxonomic issues presented by the G. rufula complex that culminated in this paper, to which he has provided support.

Remarks. Long songs and short songs of G. gravesi and its sister species, G. oneilli and G. obscura , are unique in the complex and set them apart from all other populations at the species level. Although fewer vocal differences distinguish G. gravesi and G. oneilli than the substantial vocal differences distinguishing G. obscura from its sisters, all three taxa are supported at the species level by plumage distinctions. Comparing plumages of the three taxa, the lighter coloration of the underparts of the geographically intermediate G. oneilli were separable in blind tests from the browner G. gravesi and G. obscura . The mtDNA genetic distance was greatest between G. gravesi and G. oneilli (~5%) and was least between G. gravesi and G. obscura (~3%), but the greatest number of vocal differences were found between G. obscura and G. gravesi , as well as between G. obscura and G. oneilli .

Figures

FIGURE 10. Songs of Grallaria gravesi: (A) long song, Bosque Unchog, Huánuco, Peru (Valqui ML236895); (B) short song, 34 km ENE of Huánuco, Huánuco (Cáceres ML168656).