Proposal (387) to South American Classification Committee

 

Split Poospiza cabanisi from P. lateralis

 

 

Effect on South American CL: This proposal would split Poospiza lateralis (Red-rumped Warbling-Finch) into two species, P. lateralis and P. cabanisi.

 

Poospiza lateralis lateralis is known from the mountains of Espírito Santo, Rio de Janeiro, northern Sčo Paulo, and adjacent parts of Minas Gerais.

 

Poospiza lateralis cabanisi occurs between Buenos Aires and the southern portion of Sčo Paulo, including Uruguay and eastern Paraguay.

 

Poospiza lateralis was originally described by Nordmann (1835) as Fringilla lateralis, based on specimens from “Brazil”, and subsequently included in the genus Poospiza by Cabanis (1847).

 

Poospiza cabanisi Bonaparte (1850) was described based on a specimen alleged from “Paraguay”, differing in smaller size and some differences of color, especially the underparts.

 

P. cabanisi has been treated as subspecies of P. lateralis in most of the 20th century  (Dabbene 1912, Hellmayr 1938, Paynter 1970, Dickinson 2003).

 

Hellmayr (1938) designated “Rio de Janeiro” as the type locality of northern P. lateralis and “Bonpland, Misiones” as the origin of type specimen of southern P. cabanisi (deposited in Paris Museum).

 

Ridgely and Tudor (1989) suggested the possibility that there are two species, P. lateralis and P. cabanisi, because there is no intergradation between them.

 

From a viewpoint of the PSC, Assis et al. (2007) advocated treating P. cabanisi at the species rank. The analysis of these authors showed that plumage, morphometrics, and vocalizations of this pair of species differ diagnostically, with a complete segregation of characters. Important: these two taxa are allopatric by 300 km.

 

Recommendation:

 

Mainly due to geographical isolation, the stability of the characters of each form and my personal experience with the involved taxa I recommend a "YES" vote on accepting this warbling-finch (Assis et al. did not suggest an English name) as (indeed) a biological species to our list.

Literature Cited:

 

Assis, C. P., M. A. Raposo & R. Parrini (2007) Validaćčo de Poospiza cabanisi Bonaparte, 1850 (Passeriformes: Emberizidae). Revista Brasileira de Ornitologia 15(1):103-102.

Bonaparte, C. L. (1850) Conspectus generum avium. Lugduni Batavorum: E.J. Brill.

Cabanis, J. (1847) Ornithologische Notizen. Arch. Naturgesch. 13:186-352.

Dabbene, R. (1912) Contribución a la ornitología del Paraguay. Anales del Museo Nacional de Buenos Aires 23: 283-390.

Dickinson, E. C. (2003). The Howard and Moore Complete Checklist of the Birds of the World. Princeton, N. J.: Princeton Univ. Press.

Hellmayr, C. E. (1938) Catalog of birds of the Americas and adjacent islands. Field Museum of Natural History Publications in Zoology 11: 1-662.

Nordmann, A. von. (1835). Vogel. In: Erman, A. (Ed.). Reise um die Erde durch Nord-Asien und die beiden Oceane in den Jahren 1828, 1829 und 1830….Berlin: G. Reimer.

Paynter, R. A., Jr. (1970) Subfamily Emberizinae. In: Check-list of birds of the world Vol. 13. Cambridge: Museum of Comparative Zoology.

Ridgely, R. S. e G. Tudor (1989) The birds of South America: the oscine passerines. Oxford: Oxford University Press

 

José Fernando Pacheco, January 2009

 

 

Comments from Nores: “YES, aunque sólo por las vocalizaciones. Las diferencias de coloración y medidas pueden corresponder a subespecies.

 

“Nota: Desde hace bastante tiempo, veo que en algunas propuestas que intentan elevar subespecies a especies, se seĖala el hecho de que las formas sean alopátricas para apoyar la propuesta, siendo que la cosa es al revés. Las subespecies son casi siempre alopátricas (raramente parpátricas), mientras que las especies, como todos sabemos, pueden ser alopátricas o simpátricas. O sea que cuando dos formas muy similares son alopátricas, como en el caso de estas Poospiza, lo más lógico es que por distribución sean subespecies. Si hay diferencias en canto o genéticas la situación es otra. Además, resulta difícil pensar que pueda haber intergradación en dos formas separadas por 300 km. Si estuvieran en contacto la cosa sería diferente. En caso de aceptarse la propuesta, Ridgely y Tudor proponen el nombre de Gray-throated Warbling-Finch para P. lateralis y Buff-throated Warbling-Finch para P. cabanisi que parece bien, aunque Gray-chested Warbling-Finch y Buff-chested Warbling-Finch, podría ser mejor porque en la garganta no tienen tan marcado el color, sino que son más blancuzcas.”

 

Comments from Zimmer: “YES.  Morphology, vocal differences, and range disjunction all support treating these two taxa as separate species.  Furthermore, the gap between their ranges (in Sčo Paulo state) coincides with the break between other pairs of closely related taxa that already are or soon will be considered separate species (e.g. Merulaxis ater group, Cichlocolaptes leucophrus/holti, Stephanoxis lalandi/loddigesii, Hylopezus nattereri group, etc.).  Most of these other taxon pairs represent morphologically cryptic species-pairs, whereas the two Poospiza under discussion are very different looking birds.”

 

Comments from Jaramillo: “YES.  I am only personally familiar with cabanisi, so I had to look up descriptions of lateralis for comparison as well as photos on the Internet. I was quite amazed at how different the two are, with lateralis largely lacking a supercilium, having buffy throat, bold and distinct bay sides that were extensive, grey head and back, lots of white in the tail, and a distinctive white slash on the folded primaries; quite different from the birds I am familiar with from farther south (full supercilium, grey throat and breast, dull cinnamon flanks, weak pale slash on wings, white restricted to tail corners, grey head contrasting with rufous – brown back). I could not find songs to compare, but on xeno-canto there were calls, and lateralis has a very distinctive sharp call, unlike the weak “tseep” of cabanisi, in oscines call differences to me are often a better clue to species level differences than song; at least it suggests to me a long period of isolation. I am convinced that there are vocal and clear plumage differences, no evidence of hybridization, and a break in distribution that matches up to other species level taxa in other groups – all make me think that this is a good biological species division between these two related taxa.”

 

Comments from Robbins: “YES.  Thoroughly documented.”

 

Comments from Stotz: “YES.  These are really quite different birds, both vocally and in plumage. I would favor using Ridgely and Tudor’s suggested English names of Buff-throated Warbling-Finch (for lateralis) and Gray-throated Warbling-Finch (for cabanisi).”

 

Comments from Remsen:  “YES, but with much less enthusiasm than others.  That the plumage and morphometrics are diagnosably different indicates only that cabanisi is a valid taxon, not that the rank of that taxon is necessarily “species.”  As Manuel pointed out, that they are allopatric is nearly irrelevant in the current arguments as to whether cabanisi should be ranked as a species or subspecies; if they were indeed parapatric or sympatric, then we would have a “test” of species rank under the BSC or any species concept.  The modern operational definition of subspecies is consistent with the rank’s original conceptual definitions, i.e., a subspecies is a diagnosable taxon that has not diverged to the point associated with species-level differences in the group.  The only data in Assis et al. relevant to that point is the data on vocalizations, which I would consider sufficient to place the burden-of-proof on those who would rank cabanisi as a subspecies of lateralis.”

 

Comments from Stiles: “YES, for reasons given by various members of SACC .”