Proposal (123) to South American Classification Committee
Split Melanerpes pulcher from M. chrysauchen
Effect on South American CL: This would elevate a taxon to species rank that that we treat as a subspecies of a species on our list; it is the only subspecies of that subspecies in South America.
Background: The Colombian taxon pulcher was formerly (e.g., Cory 1919) regarded as a separate species from Melanerpes chrysauchen, but they were treated as conspecific by Peters (1948). Eisenmann (1955), however, continued to treat pulcher as a species, and Wetmore (1968) provided rationale for treating this treatment. However, this has not been followed by subsequent authors (Meyer de Schauensee 1970, Ridgely 1976, Short 1982, AOU 1983, 1998, Hilty & Brown 1986, Ridgely & Gwynne 1989, Sibley & Monroe 1990, Winkler et al. 1995, Winkler & Christie 2002), except for Stiles & Skutch (1989), who tacitly followed Wetmore (1968).
Pulcher is endemic to the Magdalena Valley of n. Colombia; its distribution is disjunct from that of nominate chrysauchen, which is found from sw. Costa Rica to w. Panama.
Pulcher differs from nominate chrysauchen in several aspects of plumage (from Winkler & Christie 2002): (1) white on mantle is partly barred, (2) paler forehead patch extends to forecrown, (4) belly more extensively barred, and (5) male's red crown extends all the way to the nape. The females differ more; in chrysauchen, the crown is mostly yellowish with a narrow transverse black band, whereas in pulcher, the forehead is whitish, most of the crown in black, and the hindcrown is red, with yellowish only on the nape.
No other differences (e.g., voice) between the two have been reported as far as I know.
"New" information: Wetmore (1968) considered pulcher to deserve species rank; he wrote:
"Peters  and other writers have recently listed Centurus pulcher (Sclater) of northern Colombia as a subspecies of chrysauchen, but after careful study this does not seem warranted. A series of 11 specimens of that bird collected by M. A. Carriker, Jr., in Antioquia, Bolívar, and Santander, differ in .... [enumeration of the plumage characters above] . The two are undoubtedly are allied but differ so definitely, and are so widely separated geographically, that they appear specifically distinct."
Analysis: There's not much to analyze. Cory, Eisenmann, Wetmore, and Stiles & Skutch considered the plumage characters of pulcher sufficiently different from chrysauchen to merit species rank, whereas others did not. The former set of authors has an explicit rationale, whereas the lumpers did not. However, Wetmore did not place his rationale in any sort of comparative framework, e.g., along the lines of "if allopatric melanerpine taxa X, Y, and Z are ranked as species, then pulcher also should be considered a species" or "if parapatric melanerpine taxa X and Y are not freely interbreeding, and they differ less from each other than do pulcher and chrysauchen, then ... ."Regardless of which treatment an author followed, I suspect that Wetmore was really the only one who gave this situation any serious consideration.
Cruising through Winkler & Christie (2002), I can find at least one example that would support treating them as conspecific from the comparative standpoint. Melanerpes aurifrons has strong geographic variation, with some subspecies, e.g., dubius, having almost entirely red crowns and red bellies (these are golden or gray except for center of crown in nominate aurifrons); yet these subspecies evidently intergrade wherever in contact and are thus all treated as conspecific. More broadly, plumage color and some aspects of pattern alone don't really seem to be "important" in species limits in woodpeckers (e.g., Colaptes auratus/cafer in central North America, Colaptes melanochloros/melanolaimus in South America).
Recommendation: I don't have a strong recommendation on this one ... I could go either way depending on others' comments. This proposal was written mainly just to stimulate discussion of the issue. My inclination is to vote "NO", given within-species variation in coloration in woodpeckers, until convinced that a split is the best course.
Literature Cited (partial):
CORY, C. B. 1919. Catalogue of birds of the Americas. Field Mus. Nat. Hist. Publ., Zool. Ser., vol. 13, pt. 2, no. 2.
EISENMANN, E. 1955. The species of Middle American birds. Trans. Linn. Soc. New York 7: 1-128.
HILTY, S. L., AND W. L. BROWN. 1986. A guide to the birds of Colombia. Princeton University Press, Princeton, New Jersey.
MEYER DE SCHAUENSEE, R. 1970. A guide to the birds of South America. Livingston Publishing Co., Wynnewood, Pennsylvania.
PETERS, J. L. 1948. Check-list of birds of the world, vol. 6. Harvard University Press, Cambridge, Massachusetts.
RIDGELY R. S., AND J. A. GWYNNE. 1989. A guide to the birds of Panama, with Costa Rica, Nicaragua, and Honduras (2nd ed.). Princeton Univ. Press, Princeton, New Jersey.
SHORT, L. L., JR. 1982. Woodpeckers of the world. Delaware Museum of Natural History, Greenville, Delaware.
SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale University Press, New Haven, Connecticut.
STILES, F. G., AND A. SKUTCH. 1989. A guide to the birds of Costa Rica. Cornell Univ. Press, Ithaca, New York.
WETMORE, A. 1968. The birds of the Republic of Panamá, part 2. Smithsonian Misc. Collect., vol. 150.
WINKLER, H., AND D. A. CHRISTIE. 2002. Family Picidae (woodpeckers. Pp. 296-558 in "Handbook of the Birds of the World, Vol. 7. Jacamars to woodpeckers." (J. del Hoyo et al., eds.). Lynx Edicions, Barcelona.
WINKLER, H., D. A. CHRISTIE, AND D. NURNEY. 1995. Woodpeckers. Houghton Mifflin, Boston.
Van Remsen, April 2004
Comments from Stiles: "[YES] another tough one, though I have experience with both forms involved. The plumage differences are of a magnitude that could go either way. Behaviorally, ecologically and vocally (to my ear) chrysauchen and pulcher are extremely similar if not identical but then again, so is pucherani (which nobody has suggested lumping), and it is not so vastly different in plumage. The ranges of pucherani and pulcher must approach very closely in N Colombia but I am unaware of any specific site where they have both been reported, and know of no reported hybrids. In birds of CR, I accepted Wetmore’s split simply because I knew of no other reasonably detailed analysis (and still don’t) and because of my ignorance of pulcher. My (weak) inclination would be to consider pucherani, chrysauchen and pulcher allospecies of a superspecies, but I am aware that the superspecies category has been considerably abused in woodpeckers by Short (and the AOU). For instance, rubricapillus and hoffmanni are placed in different superspecies but hybridize massively where they come into contact (since the 1980,s) in SW Costa Rica I mentioned this, including specimens, in the CR guide to no avail, but didn’t publish anything more specific because at that time I was moving to Colombia and a student (who then disappeared) was interested in doing a thesis on same. So here I am, on the fence, with a tendency to vote Yes but a willingness to change if cogent contrary evidence were to appear."
Comments from Robbins: "I have no strong opinion on this one. Like Van and Gary, I could go either way."
Comments from Jaramillo: "YES. Not a strong opinion here, similar to other members that have voted thus far. Woodpeckers are a difficult bunch, with some good species differing mainly in size and call, but not plumage, while others differ in plumage and not voice, and with many taxa that hybridize or intergrade. It is a mess. The influence of Lester Short in woodpecker taxonomy has been good and bad, I think that his application of the biological species concept appears to have been very rigid and conservative, and hides much of the complexity that is actually present within this family."
Comments from Nores: "SI. Yo primeramente había escrito que No, pero aclarando que pensaba firmemente que podría ser una especie distinta, tan válida con M. pucherani y M. chrysauchen. Después de leer el comentario de Stiles voto que Sí."
Comments from Silva: "YES. My decision is based on Gary's comments."
Comments from Zimmer: "I vote "YES". I'm not overwhelmed by the plumage distinctions, but these, coupled with the range disjunction and the well-established pattern of endemism in the Chiriquí region of SW Costa Rica and W Panama leads me to believe that we are talking about separate species. Gary's experience with both forms (I'm familiar only with chrysauchen) carries a lot of weight with me."
Comments from Stotz: "NO. While in many respects this case resembles the previous two woodpecker splits, it differs in being in a genus with pretty extensive morphological variation with and among species. In terms of plumage, pulcher doesn't seem all that different (although I have to admit that pucherani isn't either), and there are no obvious vocal differences. In the absence of any serious evidence to support a split of this species (even unpublished), I have to vote no."
Comments from Pacheco: "[SIM] Eu concordo com os argumentos de Stiles e considero uma boa medida, até razões em contrário, manter pulcher em separado de chrysauchen."
Additional comments from Robbins: "YES. As I mentioned earlier, I could go either way with this one. But, to move things along, I'll vote "yes" to recognize Melanerpes pulcher as a species."