Proposal (265) to South American Classification Committee
Transfer Piculus rubiginosus and P. rivolii from Piculus to Colaptes
The genus Piculus has included two very disparate groups of woodpecker for most of the past century. Prior to Peters (1948), the members of the genus were placed in Chloronerpes Swainson, a name first given to P. rubiginosus in 1837 (Ridgway 1914, Cory 1919). However, Peters (1948) found that the name Piculus Spix, originally described for P. chrysochloros in 1824, predated Chloronerpes, and thus had priority. The unique, red-backed P. rivolii was briefly maintained in the monotypic genus Hyoxanthus Bonaparte, but most subsequent authors placed it with the fairly similar P. rubiginosus, first in Chloronerpes and later Piculus.
In modern works, ten species-level taxa have been assigned to the genus Piculus (Peters 1948, AOU 1998, Winkler and Christie 2002, Dickinson 2003, SACC). Seven of these taxa (P. chrysochloros, P. aurulentus, P. flavigula, P. simplex, P. callopterus, P. litae, and P. leucolaemus; hereafter called the "true Piculus") all share similar morphological characters states suggesting that they make up a natural, monophyletic assemblage: rufous underwings, Dryocopus-like crest, yellow "bridal" mark on face (absent in P. simplex, includes solid yellow auriculars in P. flavigula), and raspy voice (raspy quality lacking in P. aurulentus), with no rapid rattle. The remaining three species currently included in the genus, P. rubiginosus (including the northeast Mexican subspecies, aeruginosus, sometimes considered a full species), P. auricularis, and P. rivolii (hereafter, called the "Chloronerpes group"), lack all the above character states. Instead, these three species share different character states among themselves suggesting that they can be excluded from Piculus without causing paraphyly in that genus: yellow underwings, no crest, solid cream-colored auriculars, and clear single-note and rattle vocalizations (although single-note call appears to be missing from trans-Andean subspecies P. rubiginosus rubripileus and gularis from Colombia, Ecuador, and Peru, and voice of Mexican P. r. aeruginosus also appears to be strikingly different). Most members of the genus Colaptes share the states exhibited by the Chloronerpes group.
Genus Colaptes, the "flickers," are a group of woodpeckers that were formerly placed in several genera, now considered subgenera following Short (1965a): Chrysoptilus Swainson (type species C. punctigula), Colaptes Vigors (type species C. auratus), Nesoceleus Sclater and Salvin (monotypic, C. fernandinae), Soroplex Gloger (type species C. campestris), and Pituipicus Bonaparte (monotypic, C. pitius, now generally thought to be nested within Soroplex, e.g., Short 1972). Short was not the first to suggest that Soroplex and Pituipicus were best placed in Colaptes (e.g., Peters 1948). Indeed, most of the species in these subgenera were originally described as members of Colaptes. However, Short was novel in suggesting that Colaptes be enlarged to include Neoceleus and Chrysoptilus, giving his reasoning in a series of papers (Short 1965a, 1965b, 1967, 1972). Interestingly, he repeatedly conceded the similarity, and hence close relationship, between the Chrysoptilus "forest flickers" and the Piculus woodpeckers, particularly the Chloronerpes group. By modern phylogenetic and systematic standards, to suggest a close relationship between certain taxa placed in two genera but without including both genera in their entirety is to suggest polyphyly.
Several authors, most recently, Ridgely and Greenfield (2001), have maintained Chrysoptilus and stated that the differences between it and Colaptes "far outweigh the similarities" without giving details to support this statement. However, Ridgely and Greenfield (2001) do not make clear if their Chrysoptilus contained melanochloros and atricollis as well as punctigula.
Among plumage characters, the only obvious character that seems to separate the Chloronerpes group from Colaptes flickers appears to be the lack of barring on the back. However, some individuals of P. rubiginosus rubripileus (from the Pacific coast of Ecuador and northern Peru) do, in fact, have a noticeably strong suggestion of back barring (specimens at Louisiana State University Museum of Natural Science). Thus, this character seems a far weaker reason for separation. In fact, based on voice, plumage pattern, and biogeography, I predict that the trans-Andean rubripileus group (including Colombian gularis) will be found to be closely related to Colaptes atricollis of western Peru; the rubripileus group is worthy of additional taxonomic study, as it may warrant specific separation from rubiginosus.
In the phylogenetic tree of Prychitko and Moore (2000), two members of Colaptes (C. atricollis, generally considered a member of the "forest flickers," and C. rupicola, a species of open treeline and puna habitats in the high Andes mountains) and two Piculus (P. rubiginosus and P. rivolii) were chosen; unfortunately, no member of the true Piculus was also included. This taxon-sampling oversight was corrected by Bentz et al. (2006) who showed that, indeed, Piculus rubiginosus is nested within Colaptes, whereas Piculus chrysochloros is basal to the Colaptes clade. Bentz et al. (2006) subsequently stated the following;
"Finally..., we confirmed paraphyly in Colaptes and Piculus through inclusion of additional taxa including the type species of Piculus (P. chrysochloros). Consequently, Piculus should be defined more narrowly to include only P. chrysochloros, P. leucolaemus, P. flavigula, and P. aurulentus; given their likely close relationships with taxa studied, P. simplex, P. callopterus, and P. litae would fall into this group. The remainder of Piculus, including P. rubiginosus and P. rivolii, and likely P. auricularis (given its close association with P. rubiginosus), should be reallocated to Colaptes."
In summary, I suggest removing the species "Piculus" rubiginosus, P. auricularis (extralimital), and P. rivolii from the genus Piculus and placed within Colaptes.
Recommendation: A vote of "YES" supports the transfer of the "Chloronerpes" woodpeckers from their current allocation in Piculus to be placed within Colaptes.
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Peters, J. L. 1948. Check-list of birds of the world. Volume VI. Harvard University Press, Cambridge.
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Short, L. L. 1965a. Hybridization in the flickers (Colaptes) of North America. Bulletin of the American Museum of Natural History 129 (4): 309-428.
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Daniel Lane (March 2007)
Comments from Robbins: "YES, based on Moore et al.'s (2000) and our (Benz et al. 2006) data sets it is clear that rubiginosus and rivolii should be moved to Colaptes."
Comments from Stiles: "YES. Genetic, morphological and vocal evidence support this move, I see no reason to delay it."
Comments solicited from Bill Moore: "The summary statement I quote from Dan Lane's proposal, and the reasoning justifying it is correct.
" 'In summary, I suggest removing the species "Piculus" rubiginosus, P. auricularis (extralimital), and P. rivolii from the genus Piculus and placed within Colaptes.' "
"Although publication on Colaptes and Piculus by my lab is scattered - and for that I apologize - the correct placement of P. rivolii and P. rubiginosus in Colaptes is implicit in that scattering. I don't think we have published this, but inclusion of P. auricularis in Colaptes is correct also. We have an unpublished (but hope to be published) phylogeny that confirms Dan Lane's proposal (265). It is also the case that P. rubiginosus, as he suggests, is paraphyletic: the Mexican form is sister to P. auricularis, the Peruvian form is sister to C. atricollis."
Comments from Jaramillo: "YES - This seems like a clearly needed change, based on molecular, plumage, and vocal data."
Comments from Pacheco: "YES. Duas análises independentes convergem neste ponto, em combinação com outros dados disponíveis, dão suficiente suporte a esta transferência como bem apresentado por Lane."
Comments from Nores: "YES. Los datos moleculares de Moore et al.'s (2000) y (Benz et al. 2006) muestran claramente que P. rubiginosus and rivolii deben ser puestos en Colaptes. Las diferencias de color entre Piculus rubiginosus con P. chrysochloros y P. aurulentus es un hecho que siempre me había llamado la atención e intuitivamente me parecía que no podían pertenecer al mismo género."