A new species of antpitta (formicariidae: Grallaria) from the southern Ecuadorian Andes

ABSTRACT.-We describe a striking new species of Grallaria antpitta from wet, upper subtropical forest in the upper Rio Chinchipe drainage, provincia Zamora-Chinchipe, Ecuador. Notes on its natural history and molecular systematics are presented along with spectrograms of its voice. The species is readily diagnosed by its large size, unique white facial markings, and voice. Initial results from DNA sequence analyses place the new species in a well-supported clade that includes Grallaria nuchalis (which is syntopic with the new species), G. hypoleuca, G. watkinsi, and G. ruficapilla. Received 23 September 1998, accepted 22 April 1999.

RESUMEN.-Una sorprendente nueva especie del genero Grallaria (Aves: Formicariidae) es descrita de un bosque humedo de la zona subtropical alta del drenaje del Rio Chine-hipe, provincia Zamora-Chinchipe, Ecuador. Se presentan notas acerca de su historic natural y sistematica molecular, en conjunto con espectrogramas de sus vocalizaciones. La nueva especie se diferencia claramente por su gran tamano, sus marcas faciales blancas, y su peculiar voz. Analisis iniciales de sequencias del ADN colocan a la nueva especie en un clado que incluye a Grallaria nuchalis (que es sint6pica con la nueva especie), G. hypoleuca, G. watkinsi, y G. ruficapilla.

FIELD WORK IN SOUTH AMERICA during the past 25 years has resulted in the discovery of many birds new to science (Mayr and Vuilleumier 1983, Vuilleumier and Mayr 1987). New genera have been described for some species (e.g. Xenoglaux loweryi, O'Neill and Graves 1977; Acrobatornis fonsecai, Pacheco et al. 1996; Nephelornis oneilli, Lowery and Tallman 1976), and the known ranges of other genera have been greatly extended by other new species (e.g. Nannopsittaca dachilleae, O'Neill et al. 1991; Clytoctantes atrogularis, Lanyon et al. 1990). Most discoveries, however, have been of species with obvious relatives and which fit logically into broader interpretations of their respective group's historical biogeography.

Therefore, it came as a surprise that a new species of antpitta with strikingly distinct plumage characteristics was discovered on 20 November 1997 by R. S. Ridgely, J. and R. Moore, L. Navarrete, and M. Rivadeneira during a trip to record vocalizations of Ecuadorian birds. Ridgely, the Moores, and Navarrete returned on 21 November 1997 to record and photograph the bird, and M. Jacome, Navarrete, X. Munoz, and E Sornoza M. visited the site on 27 to 29 December 1997 and collected the first specimen. A team from the Academy of Natural Sciences of Philadelphia (ANSP), the Museo Ecuatoriano de Ciencias Naturales (MECN), the Zoological Museum of the University of Copenhagen (ZMUC), and others (D. J. Agro, A. D. Brewer, N. Krabbe, L. Navarrete, R. S. Ridgely, N. Simpson, E Sornoza M., and D. L. Wechsler) returned to the original site between 13 and 22 January 1998 to assess population size and habitat requirements and to obtain further specimens and photographs of the bird. Sornoza and Jacome obtained an additional specimen during a visit to nearby Cerro Toledo from 16 to 31 March 1998.

Five specimens of the new bird were collected and compared with specimens of other formicariids. They clearly represent a new taxon that we propose to name:

Grallaria ridgelyi sp. nov. Jocotoco Antpitta

Holotype.-MECN No. 7199, adult male (skull ossified, no bursa of Fabricius), collected 28 December 1997 by F.Sornoza M. (FS 1922) in Quebrada Honda, provincia Zamora-Chinchipe, Ecuador (04 deg 29'S, 79 deg 08'W; elevation 2,520 m). Vocal recordings are archived at the Library of Natural Sounds (LNS 79055). A blood sample (FS-1-28.12.97) is deposited at the Institute for Population Ecology, Copenhagen University (IPE); tissue samples are deposited as ANSP 8701.

Diagnosis.-A large antpitta (body mass 150 to 200 g) assignable to the genus Grallaria. Separable from known antpittas by white cheek patch of rigid loose-barbed feathers with glossy shafts extending from the subocular and posterior part of the lower lores to the base of the bill (see Fig. 1). The white cheek patch contrasts sharply with the black cap, bill, malar region, and anterior auricular feathers. The new species differs from all other Grallaria in lacking true rictal bristles. The throat feathers are white, stiff, and loose-barbed, as in the Ochrestriped Antpitta (G. dignissima), but are denser, shorter, and with more recurved tips, as in Chestnut-naped Antpitta (G. nuchalis). The gray of the underparts is interspersed with white in a pattern resembling pale-bellied members of the G. hypoleuca allospecies group. The bill is shaped most like that of G. nuchalis and the Pale-billed Antpitta (G. carrikeri) but is proportionately deeper at the base and with a straighter culmen. Tarsi and toes proportionately larger than in other antpittas and as large as in Giant Antpitta (G. gigantea). Tarsal scutes few and distinctly ridged with toes and claws short and sturdy, resembling G. nuchalis.

Description of holotype.-Crown, a 1 to 2-mm wide feathered ocular ring, broad malars, and anterior auriculars connecting with malars Jet Black (capitalized color names and numbers follow Smithe 1975). A large and distinct fanshaped patch of rigid, loose-barbed white feathers with glossy shafts in the loral and subocular region (see Fig. 1). These feathers are longer and denser than in congeners and cover the base of the bill and most of the malar region. Rictal bristles lacking, but a few of the white loral feathers have elongated bare shafts, forming bristle-like extensions. Poorly defined postocular streak, posterior part of auriculars, and sides of neck Light Neutral Gray (85). Nape black but suffused with color of back, which is closest to Brownish Olive (129), but more golden. Upper mantle with black wash that decreases posteriorly. All back feathers with blackish shafts. Tail, composed of 12 rectrices, between Raw Umber (223) and Mars Brown (223A). The three innermost secondaries and outer webs of the nine other secondaries slightly lighter than Chestnut (32). The distal half of the outer webs of the 10 primaries are Ground Cinnamon (239), the inner webs of the remiges are blackish, and the underwing primary coverts are mostly black. Upperwing coverts Brownish Olive with 2-mm wide blackish shaft streaks and Chestnut edges and tips that are bordered by a 1-mm wide blackish band. Alula Brownish Olive like back, outer webs nearly uniform. Breast White with light suffusion of Light Neutral Gray. Throat white, feathers with fairly stiff, glossy, elongated and recurved shafts that on some chin feathers are faintly dark-tipped.