Proposal (37) to South American Classification Committee
Split Synallaxis chinchipensis from S. stictothorax
Effect on South American CL: This proposal would elevate a taxon to species rank that we currently treat as a subspecies on our baseline list.
Background: For most of their history, the taxon chinchipensis has been treated as a subspecies of "Synallaxis" stictothorax (Necklaced Spinetail). They are allopatric (nearly parapatric) taxa with no known contact zone; chinchipensis is endemic to the Mara–on valley and nominate stictothorax and the subspecies maculata are found in western Peru and Ecuador. No published data exist on characters directly relevant to assessing potential interbreeding such as vocalizations; voices are not even described as being different, and an analysis has not been published. They are (presumably) 100% diagnosable phenotypic units based on plumage characters. The primary differences in plumage are (1) the superciliary of chinchipensis is much less conspicuous and grayish rather than white, (2) the breast markings are more in the form of spots than streaks, and (3) the flanks are more grayish. Chinchipensis is larger in body size and longer-billed, but degree of overlap if any, has not been quantified.
Peters (1951), Meyer de Schauensee (1966, 1970), Vaurie (1980), and Sibley & Monroe (1990) treated them as conspecific. Ridgely & Tudor (1994) considered them to be separate species based solely on "plumage and morphological differences." This treatment was followed by Ridgely & Greenfield (2001). Remsen (2003) maintained them as conspecific and noted that published evidence for treating chinchipensis is weak.
Ned Johnson was working on this problem but died before he could finish it. Whether others will pick up and continue with his project (and relationship to Siptornopsis) is being discussed but uncertain.
Analysis: This problem is like perhaps several hundred others in South America with respect to species-ranking of allopatric sister taxa: we don't have enough data to make a sound decision one way or another, but we need to deal with them [at least this allows me to copy-paste identical text among proposals]. It would be reasonably easy to obtain vocal data on these two -- certainly recordings of both already exist. The plumage differences suggest species rank, but without vocal or other data, I do not find the case convincing.
Recommendation: I will vote "NO" on this proposal because in the absence of published data, I see no reason to change our current classification. My "gut feeling: is that that Bob and others are correct in elevating chinchipensis to species rank, but until some sort of data are published, I think we should remain conservative.
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.
PETERS, J. L. 1951. Check-list of birds of the world, vol. 7. Museum of Comparative Zoology, Cambridge, Massachusetts.
REMSEN, J. V., JR. 2003 (in press). Family Furnariidae (ovenbirds). Pp. #-# in "Handbook of the Birds of the World," Vol. 8. Broadbills to Tapaculos (del Hoyo, J. et al., eds.). Lynx Edicions, Barcelona.
RIDGELY, R. S., AND G. TUDOR. 1994. The birds of South America, vol. 2. Univ. Texas Press, Austin.
RIDGELY, R. S., AND P. J. GREENFIELD. 2001. The birds of Ecuador. Vol. I. Status, distribution, and taxonomy. Cornell University Press, Ithaca, New York.
SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale University Press, New Haven, Connecticut.
VAURIE, C. 1980. Taxonomy and geographical distribution of the Furnariidae (Aves, Passeriformes). Bulletin of the American Museum of Natural History 166: 1-357.
Van Remsen, July 2003
P.S.: If the proposal does not pass, then I'll work on another one on the English names of these two.
Comments from Schulenberg: "My vote: "No". It wouldn't surprise me if a case could be made for splitting chinchipensis, but I agree that the published evidence is not very strong. I also wonder if authors would have been as quick to split chinchipensis if they had been aware of the undescribed, white-breasted (i.e., no necklace at all) population of Necklaced Spinetail on the coast of Peru at the southern end of the range of stictothorax. "
Comments from Robbins: "NO, but I'm on the fence on this one."
Comments from Stotz: "Leave as conspecific, no vocal differences have been noted and there is an additional unresolved taxon to think about."
Comments from Zimmer: "Another tough one. Although duets of this taxon (chinchipensis) are very similar to duets of Necklaced Spinetail, in my experience the two have some differences in their most commonly given vocalizations. Combined with the morphological differences and the fact that these differences reflect an established biogeographic pattern, I think the case is good for splitting. Once again however, the argument hinges on vocal differences that have not been documented in the literature. Until some sort of analysis is published, record me as a reluctant "no" vote."
Comments from Stiles: ̉NO (until evidence is in)."
Comments from Silva: "Yes. Taking in account the plumage differences and the geographical distribution, I think we have a good case to recognize these two taxa as distinct biological species, although a formal analyses could be desired."
Comments from Jaramillo: "NO. Need voice data, and inclusion of white-breasted taxon mentioned by Tom in analysis."