Proposal (785) to South American Classification Committee
Treat Myrmothera subcanescens as a separate species from M. campanisona
Background: Myrmothera campanisona (Thrush-like Antpitta) is a common widespread species in Amazonia, distributed from eastern Colombia south to northern Bolivia and east to the Guianas and eastern Amazonian Brazil, both north and south of the Amazon River. Six subspecies generally are recognized (e.g., Krabbe and Schulenberg 1993, Dickinson and Christidis 2014), (quote) despite seemingly little variation in plumage (end quote) (Greeney 2017).
On the other hand, Krabbe and Schulenberg (1993) noted an interesting pattern of geographic variation in the vocalizations of the species. The song of most populations consists of a series of notes that falls, or rises and then falls; the song of subcanescens (Brazil south of the Amazon, east of the Madeira River), on the other hand, is (quote) distinctly different, gradually increasing in volume, and rising steadily in pitch (end quote) (Krabbe and Schulenberg 1993). This difference also has been noticed (independently?) by Kevin Zimmer and Andrew Whittaker (cited in Ridgely and Tudor 2009). There are many examples of recordings of these vocalizations at and at ; representative recordings include
Krabbe and Schulenberg (1993) commented that these vocal differences suggested that subcanescens might be a separate species, but there has been no follow-up work on this.
New information: Carneiro et al. (2018) conducted a phylogenetic analysis of the lowland antpittas (Hylopezus and Myrmothera), based on sequence data from two mitochondrial genes and three nuclear introns. There are a number of interesting results from this paper affecting the nomenclature of Hylopezus and Myrmothera that, sooner or later, SACC will have to consider. This proposal addresses the main implication for SACC at the species level, paraphyly in Myrmothera campanisona.
Within Myrmothera (as currently defined), Carneiro et al. found four clades. They recover the same phylogeny using only mtDNA, and from a concatenated data set incorporating both mtDNA and nuDNA. The basal clade (their clade Myrmothera campanisona C) represents samples of M. campanisona from across most of the range of the species (Colombia south to Bolivia, and east, north of the Amazon, to the Guianas and northern Brazil). The next two major clades correspond to Myrmothera simplex (Tepui Antpitta); and a sister clade composed to two subclades, with a relatively shallow divergence between them, corresponding to samples of M. campanisona from the right bank of the upper Rio Madeira (their clade Myrmothera campanisona B), and samples from the Rio Tapajos (both banks) and the left bank of the Rio Xingu (their clade Myrmothera campanisona A).
These two subclades collectively represent subcanescens (type locality Colonia do Mojuy, near Santarém, on the right bank of the lower Tapajos; Todd 1927). Note that although there are two genetic subclades in this group, subcanescens is the only available name for any population in this region, and to date no morphological or vocal differences have been described for the A and B subclades.
Analysis: Clearly Myrmothera campanisona is paraphyletic with respect to M. simplex. And, as noted above, these genetic differences between subcanescens and other M. campanisona also correspond to a clear vocal divergence. I fully endorse the recommendation by Carneiro et al. to recognize subcanescens as a species.
English names: There is no Hellmayr name for subcanescens; the relevant volume of Cory and Hellmayr was published in 1924, but subcanescens was described in 1927. We probably wouldn't want a Hellmayr name for this taxon anyway (the Cory and Hellmayr name for campanisona is Little Antpitta). And Todd did not concern himself much with English names. The name Tapajos Antpitta is in use by del Hoyo and Collar (2016), who do not split subcanescens, but who do recognize it as subspecies group; and this name also was proposed by Carneiro et al. (2018). This species obviously is not restricted to the Tapajos drainage, but this is a good enough name for me. I do not see any reason to tinker with the English name for Myrmothera campanisona sensu stricto, as Thrush-like Antpitta is a well-established name by now, and M. campanisona is much more widespread than M. subcanescens.
Recommendations: I propose breaking this proposal down into three parts:
Part A): to recognize Myrmothera subcanescens as a species. My recommendation is Yes.
Part B): to adopt Tapajos Antpitta as the English name for Myrmothera subcanescens. My recommendation is Yes, unless someone who votes No also proposes a name that clearly is better.
Part C): to retain Thrush-like Antpitta as the English name for Myrmothera campanisona sensu stricto. My recommendation is Yes.
Carneiro, L., G.A. Bravo, N. Aristizábal, A.M. Cuervo, and A. Aleixo. 2018. Molecular systematics and biogeography of lowland antpittas (Aves, Grallariidae): the role of vicariance and dispersal in the diversification of a widespread Neotropical lineage. Molecular Phylogenetics and Evolution 120: 375–389.
Cory, C.B., and C.E. Hellmayr. 1924. . .
Dickinson, E.C., and L. Christidis. 2014. The Howard & Moore complete checklist of the birds of the world. Fourth edition. Volume 2. Aves Press, Eastbourne, United Kingdom.
Greeney, H.F. 2017. , version 1.0. in T.S. Schulenberg (editor), Neotropical Birds. Cornell Lab of Ornithology, Ithaca, New York.
del Hoyo, J., and N.J. Collar. 2016. HBW and BirdLife International illustrated checklist of the birds of the world. Volume 2. Barcelona: Lynx Edicions.
Krabbe, N., and T.S. Schulenberg. 2003. Family Formicariidae (ground-antbirds). Pages 682-731 in J. del Hoyo, A. Elliott, and D.A. Christie (editors), Handbook of the birds of the world. Volume 8. Lynx Edicions, Barcelona.
Ridgely, R. S., and G. Tudor. 2009. Field guide to the songbirds of South America. The passerines. University of Texas Press, Austin, Texas.
Todd, W.E.C. 1927. . .
Tom Schulenberg, April 2018
Comments from Robbins: “YES, genetic and vocal data clearly indicate that subcanescens should be treated as a species.”
Comments from Stiles: “YES to A: split subcanescens as a separate species, thus eliminating the paraphyly of campanisona; B: Tapajós is OK as an English name for it (at least, I can’t think of a better one); C: YES, retain Thrushlike for campanisona – at least, it preserves stability for the most widely distributed taxon.”
Comments from Pacheco: “From the genetic and vocal data now available, I vote YES for A.”
Comments from Areta: “YES. All lines of evidence converge to raise subcanescens to full species status.”
Comments from Stotz: “ “YES. Combination of vocal and genetic data make this an easy decision.”