Proposal (80) to South American Classification Committee

 

Lump Phrygilus punensis and P. atriceps

 

Effect on South American CL: This proposal would lump two species currently recognized as separate species on our baseline list.

 

Background: Species limits in the hooded sierra-finch group in the genus Phrygilus have been historically fluid, with little real data available to support any particular treatment, of which there are at least three flavors.

 

Four "units" are involved: (1) P. patagonicus, with largely austral distribution, and its status as a species never seems to have been questioned; (2) nominate gayi (with minor and caniceps) of Chile and Andean Argentina; (3) atriceps of southwestern Peru and most of the Bolivian Andes; and (4) punensis (with chloronotus) of the Peruvian Andes and northern depto. La Paz, Bolivia. They all share a similar color pattern, with blackish or gray hood, wings, and tail contrasting with yellowish green to yellowish rufescent underparts and back. Patagonicus is evidently broadly sympatric with gayi. Nonbreeding movements complicate assessment of true overlap. Although degree of actual syntopy is not clear; it is clear (from what I can tell) that gayi and patagonicus have to be considered separate species.

 

Treatment of the other three is where the problems arise. Hellmayr (1938) treated them all as subspecies of a single species. However, atriceps and gayi breed syntopically in n. Chile, according to Johnson (1967):

 

"However, our field observations have shown conclusively that from Atacama to Coquimbo the present form [atriceps] and Ph. gayi gayi live and nest in the same territory and therefore cannot be conspecific."

 

(The original discovery of syntopy was published in a paper by Philippi (1942) that I do not have.)

 

This led Meyer de Schauensee (1966, 1970) and Paynter (1970) to treat atriceps as a separate species from gayi, with inclusion of the northern, gray-headed punensis group as subspecies of black-headed atriceps.

 

Ridgely & Tudor (1989), following Franois Vuilleumier's unpublished 1967 dissertation (relevant parts of which have, I think, been published, but I can't find where), further elevated punensis (with chloronotus) to species rank. They wrote, in part:

 

"As these 2 taxa [atriceps and gayi] appear to be reproductively isolated, we conclude that these latter 2 [atriceps and punensis] should be considered separate species (though they were lumped in [Paynter 1970]). Note further, that adult females of punensis and gayi differ quite markedly."

 

This split was followed by FjeldsΠ& Krabbe (1990), Sibley & Monroe (1990), Dickinson (2003), and thus SACC.

 

Analysis: Real data on contact between atriceps and punensis, or on comparative vocalizations, are ... surprise, surprise .... absent. So, we have the usual frustrating task of working from assumptions and weak, qualitative information. The above split of punensis from atriceps was based on the assumption that if gray-headed gayi and black-headed atriceps do not interbreed, then gray-headed punensis is unlikely to interbreed with atriceps as well. The problem is that gayi differs in more ways from atriceps than punensis does from atriceps -- the comparison isn't really analogous. The overall color tones of gayi are much more greenish than those of punensis/chloronotus, which ventrally shares the rufescent tones of atriceps. Also, punensis/chloronotus have darker gray heads, closer in shade to atriceps (intermediate between head color of gayi and atriceps). Despite the similarity in head and back color between gayi and punensis, whose ranges are separated from each other by atriceps, fiddling with skins would lead most of you, I suspect, to predict that atriceps and punensis are sisters relative to gayi. In fact, gayi might be the sister to patagonicus -- they are so similar in plumage (differing mainly in size) that Johnson (1967) explicitly stated that there was no point in making plates of both of them, and he urged extreme caution in the field.

 

Recommendation: I will vote "NO" on this proposal because in the absence of real data, I see no reason to change our current classification. Although it would be easy to shoot down the evidence for the atriceps-punensis split, I think Bob did the right thing with the split, given available data, and I lean towards following it until real data are forthcoming for the following reasons: (1) head color may indeed make all the difference in species recognition -- for all we know, that indeed may be the sole basis for mate selection between atriceps and gayi in n. Chile; (2) patagonicus and gayi have virtually identical head colors yet as far is known behave as two separate gene pools despite plenty of opportunity to do otherwise; and (3) the fluidity in species limits in this group does not give any particular treatment any sort of claim to long-standing tradition for which more convincing data are required to overturn it.

 

Literature Cited:

 

DICKINSON, E. C. (ed.). 2003. The Howard and Moore complete checklist of the birds of the World, Revised and enlarged 3rd Edition. Christopher Helm, London, 1040 pp.

FJELDS, J., AND N. KRABBE. 1990. Birds of the High Andes. Zoological Museum, Univ. Copenhagen, Copenhagen, Denmark.

HELLMAYR, C. E. 1938. Catalogue of birds of the Americas. Field Mus. Nat. Hist. Publ., Zool. Ser., vol. 13., pt. 11.

MEYER DE SCHAUENSEE, R. 1966. The species of birds of South America and their distribution. Livingston Publishing Co., Narberth, Pennsylvania.

MEYER DE SCHAUENSEE, R. 1970. A guide to the birds of South America. Livingston Publishing Co., Wynnewood, Pennsylvania.

PAYNTER, R. A., JR. 1970a. Subfamily Emberizinae. Pp. 3-214 in "Check-list of birds of the World, Vol. 8" (Paynter R. A., Jr., ed.). Museum of Comparative Zoology, Cambridge, Massachusetts.

RIDGELY, R. S., AND G. TUDOR. 1989. The birds of South America, vol. 1. Univ. Texas Press, Austin.

SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale University Press, New Haven, Connecticut.

 

Van Remsen, December 2003

 

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Comments from Robbins: "I vote "NO" for this proposal for reasons outlined by Van."

 

Comments from Stiles: "NO - case is similar to no. 78, maintain the status quo until convincing evidence for change is published."

 

Comments from Jaramillo: "NO. There are complexities in this genus that make it even more of a mess than the proposal implies. The taxa patagonicus and gayi are indeed reproductively isolated for the most part. In many parts of the Chilean Andes the two species breed within kilometers of each other, patagonicus in forest, and gayi higher up in Andean scrub. However in the far south, particularly in the region of Punta Arenas where the forest blends in to the open steppe there is a narrow hybrid zone. This zone has been studied by Vuilleumier, but I could not find the reference here. The southern gayi are a different subspecies than the Andean gayi. In addition, there is a third subspecies of gayi (minor) in the coast range of Chile that is in many ways more similar to patagonicus than to gayi; it may be best classified under that taxon? I will agree that overall gayi and patagonicus behave as two good biological species. Now, there are a couple of supposed hybrid specimens between gayi and atriceps known from the Andes of Chile (Ba–os del Toro) but that is it -- otherwise the two maintain their integrity. Finally, in Bolivia I have observed atriceps and punensis in the same sites on several occasions; these observations have been in August and October. I don't know when these species breed, but I had assumed they were sympatric so was surprised to see this proposal. My guess is that they are sympatric in many areas in the highlands of Bolivia, and given that they do not appear to hybridize we are safe in keeping them separate."

 

Comments from Nores: "Yo voto NO a juntar Phrygilus punensis con atriceps. De hacer esto, habr’a tambiŽn que juntar patagonicus con gayi. Aunque estas dos formas son mayormente simp‡tricas en el sudoeste de SudamŽrica, ellas tienen muy diferente h‡bitat. P. gayi habita en la estepa y P. patagonicus habita en el bosque de Nothophagus."