Proposal (324) to South American Classification Committee
Reinstate Ochetorhynchus and merge Chilia and Eremobius into it
Effect on SACC: This would transfer two species (ruficaudus and andaecola) from their current placement in Upucerthia to a revived Ochetorhynchus and also merge the monotypic genera Chilia and Eremobius into Ochetorhynchus.
Background: SACC classification currently classifies all the earthcreepers in their traditional genus, Upucerthia. Multiple lines of evidence indicate that this genus is polyphyletic, with two of the major "offenders" being ruficaudus and andaecola. Our current Notes are as follows:
"7. The genus Ochetorhynchus was used for U. harterti and U. certhioides by Ridgely & Tudor (1994) to recognize the distinctiveness of these two species from other Upucerthia (especially with respect to nest type); however, the type species of Ochetorhynchus is ruficaudus, making that name unavailable for harterti + certhioides unless ruficaudus is also included (Remsen 2003). Peters (1951) treated those three species in Ochetorhynchus. The genus Upucerthia is highly polyphyletic (Chesser et al. 2007, Fjelds et al. 2007), with (a) harterti and certhioides in a group with Pseudocolaptes and Premnornis, (b) andaecola and ruficaudus in a group with Eremobius and Chilia, (c) serrana basal to a group that includes Cinclodes and the remaining Upucerthia (dumetaria, albigula, jelskii, and validirostris). Chesser and Brumfield (2007) named a new genus Tarphonomus for certhioides + harterti."
"9. Fjelds & Krabbe (1990) and Ridgely & Tudor (1994) proposed that Eremobius is probably more closely related to Upucerthia than to the genera near which often placed in linear sequences, but nest structure much more like synallaxine spinetails (Zyskowski and Prum 1989). Chesser et al. (2007) and Fjelds et al. (2007) found that Eremobius is the sister taxon to U. ruficaudus. Chesser et al. (2007) further recommended that Ochetorhynchus be revived for ruficaudus and that Eremobius be merged into it, as well as Chilia."
New information: As noted above, two independent genetic data sets appeared in 2007, using different genes and samples, with the same results, namely that Upucerthia consists of 4 different groups of birds, and to keep that genus monophyletic would require merger of virtually every furnariine genus into one. For example, Chesser et al. (2007) found that the two Upucerthia (ruficaudus and andaecola) that group with Eremobius and Chilia are basal to all other furnariine genera sampled, including, for example, Synallaxis, Philydor, Furnarius, and Cinclodes. With respect to this proposal, ruficaudus and andaecola form a group (100% ML and MP bootstrap) with Eremobius and Chilia, and true Upucerthia (dumetaria, albigula, validirostris, jelskii) form a group (100% ML and MP bootstrap) with Cinclodes. Their sample was based on both nuclear and mitochondrial genes (total 1927 bp), and separate analyses of mtDNA and nDNA produced similar results, as did all methods of data analysis. Note that even super-lumper Peters did not place ruficaudus in Upucerthia.
Chesser et al. (2007) recommended that the four species above be combined in a single genus. Ochetorhynchus Meyen, 1834, has priority, with ruficaudus as the type species. As noted by Chesser and Brumfield, because andaecola and ruficaudus are not sister species, recognizing separate genera for each of the four members of the group would require a new genus name for andaecola. [We do not yet have a skin of Chilia for comparison, but inclusion of the other three in a single genus unites species with shared and overlapping plumage and morphology.]
If anyone needs pdfs of these papers, let me know (or download them from Robb Brumfield's web page).
Analysis and Recommendation: In my opinion, as with the previous proposal (#323) there is no reason to hesitate on this one. Anyone familiar with these birds knows that the only thing that they shared with true Upucerthia was terrestrial foraging and a relatively long bill. The genetic data leave beyond a doubt that the genus Upucerthia grouped species that shared a morphotype, and pruning is needed to make this genus monophyletic. This proposal is the second step (see (#324), and I recommend a YES, to recognize them under the genus name Ochetorhynchus and to place them at the beginning of our linear sequence within the furnariines to reflect their basal position.
Chesser, R. T., F. K. Barker, & R. T. Brumfield. 2007. Four-fold polyphyly of the genus formerly known as Upucerthia, with notes on the systematics and evolution of the avian subfamily Furnariinae. Molecular Phylogenetics and Evolution 44:1320_1332.
[See SACC Literature Cited for others]
Van Remsen (in consultation with Robb Brumfield and Terry Chesser), December 2007
Comments from Stiles: "YES. Again, the genetic data clearly mandate this change, and the morphological data favoring placement in Upucerthia were not particularly strong in the first place."
Comments from Stotz: "YES. The variety of trees that Chesser et al provide does suggest that it is not impossible that ruficauda and andaecola are sisters, in which case we wouldn't need to sink Chilia and Eremobius. However, since those are monotypic genera, and the linkage between them and ruficauda and andaecola is so strong, it seems that lumping everything into Ochetorhynchus makes the most sense."
Comments from Zimmer: "YES for reasons stated by Van in the proposal."
Comments from Robbins: "YES. I concur with Van's rationale for transferring these four taxa into Ochetorhynchus."
Comments from Pacheco: "YES. A proposio mais uma vez acompanhada de suporte slido."
Comments from Nores: "YES. Los anlisis genticos muestran claramente esta relacin. No obstante, siempre es un poco traumtica la eliminacin de taxas tan establecidos, como en este caso los gneros Eremobius y Chilia."