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 Macaulay
Library and at xeno-canto;
representative recordings include
standard campanisona
https://www.xeno-canto.org/333610
subcanescens
https://macaulaylibrary.org/asset/88915#_ga=2.255514187.237959473.1522697535-1150616374.1458581505
https://www.xeno-canto.org/90422
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.
Literature Cited:
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. https://doi.org/10.1016/j.ympev.2017.11.019
Cory,
C.B., and C.E. Hellmayr. 1924. Catalogue of birds of the
Americas. Part III. Field Museum of Natural
History Zoological Series volume 13, part 3.
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. Thrush-like
Antpitta (Myrmothera campanisona),
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. New gnateaters and
antbirds from tropical America, with a revision of the genus Myrmeciza and its allies. Proceedings
of the Biological Society of Washington 40: 149-178.
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.”