Proposal
(505) to South American Classification Committee
Split
Thrush-like Manakin Schiffornis turdina into any of two to seven species
Background: In
Proposal 327, S. turdina was proposed to be split into five species,
based on Nyári (2007). Although several
committee members voted in favour of this treatment
(and all were in favour of some splitting), the
proposal was rejected, there has been no follow up proposal, and S.
turdina remains a single species on the AOU-SACC list. A large number of archived and published
sound recordings are now available of greater turdina in published
recording compilations and online resources such as xeno-canto. In Donegan et al. (2011), we re-examined
Nyári (2007)’s recommendations for purposes of the Colombian checklist and
recent Spanish language field guide (McMullan et al. 2011) in light of the
additional sound recordings available today.
Photographs of birds representing the three different Colombian populations
were also presented. This proposal gives
the AOU-SACC the opportunity to reconsider this over-lumped group once again.
Summary of Proposal: Nyári
(2007) presented molecular data and some sonograms, as discussed in proposal
327. The present species ‘turdina’
is a complex group obviously constituting several biological species, with
several distinctive vocal types and some instances of sympatry. In Donegan et al. (2011), we studied
geographic variation in voice, the type localities of various of the names and
priority issues. Committee members who
wish to consider the issues in more detail may wish to consult the paper,
alongside Nyári (2007)’s maps and phylogeny.
We presented a series of sonograms and studied recordings with a broader
geographical sample for recognised subspecies. We differed from Nyári (2007) in a handful of
aspects, but the bulk of Nyári (2007)’s proposals were supported by additional
materials now available.
The turdina group needs
splitting even under the most conservative of species concepts. Although this aspect was not highlighted by
Nyári (2007), two of the taxa in the turdina group are sympatric in
Central Panama (Ridgely & Gwynne 1989) and two others of them replace one
another by elevation in the Amazon-Andes interface of Ecuador and Peru (Ridgely
& Greenfield 2001, Krabbe & Nilsson 2003). Moreover, various other populations are
vocally distinct. This proposal should
therefore involve a discussion of the extent and manner in which one ought to
go about cutting off various limbs in this group so as to produce a set of
species which are vocally cohesive or, for those interested in such matters,
monophyletic (rather than a question of whether sub-division is warranted at
all). In Donegan et al. (2011), we proposed recognising
the following species (using Nyári 2007’s vernacular names):
1. Thrush-like
Schiffornis S. turdina (provisionally including subspecies steinbachi,
amazonum, wallacii and intermedia) of the Amazon region and Atlantic
forest, including the Amazonian region of Colombia.
2. Slender-billed
Schiffornis S. stenorhyncha (including panamensis) of the
Tacarcuna region of Panama and Colombia, Magdalena valley and Central, East and
Merida Andes of Colombia and north-western Venezuela.
3. Brown
Schiffornis S. veraepacis (including dumicola, rosenbergi, “buckleyi”
and acrophites) of the Chocó from northernmost
Peru through Ecuador to Colombia and Central America from northern/western
Panamá northwards.
4. Foothill
Schiffornis S. aenea of the western Amazon region of Ecuador and Peru.
5. Olivaceous
Schiffornis S. olivacea of the Guianan shield.
The table below summarises
the range of named populations and other proposed treatments:
Population
name |
Range |
Nyári
Vocal group |
Nyári’s molecular group |
Nyári’s PSC approach |
Nyári’s BSC approach |
Nyári’s SACC proposal |
Donegan
et al. 2011 BSC approach |
veraepacis,
dumicola |
Central
America (S Mexico and Belize to N/W Panama) |
A |
1 |
veraepacis |
veraepacis |
veraepacis |
veraepacis |
rosenbergi
/ buckleyi / acrophites |
Chocó
of Colombia and N Ecuador |
A |
3 |
rosenbergi |
veraepacis |
veraepacis |
veraepacis |
olivacea |
Guianan
shield of Venezuela to Suriname, N. Brazil |
A |
7 |
olivacea |
veraepacis |
olivacea |
olivacea |
aenea |
West
Amazon in Ecuador and Perú |
B |
4 |
aenea |
aenea |
aenea |
aenea |
stenorhyncha
/ panamensis |
Northern
Colombia, Venezuela, S/E Panama |
E |
2 |
stenorhyncha |
stenorhyncha |
stenorhyncha |
stenorhyncha |
turdina,
intermedia |
Atlantic
forest region of Brazil |
D |
6 |
turdina |
turdina |
turdina |
turdina |
steinbachi |
Southern
Amazonia in Peru, Bolivia, Brazil |
C |
6 |
amazonum |
amazonum |
amazonum |
turdina |
wallacii |
Para,
Brazil and surrounding region |
A/C |
6/7 |
amazona
/ olivacea |
amazonum
/ veraepacis |
amazonum
/ olivacea |
turdina |
amazonum |
Northern
Amazonia in Colombia, Venezuela, Peru, Bolivia, Brazil. |
C |
5 |
amazonum |
amazonum |
amazonum
/ turdina |
turdina |
Sub-proposals: This
proposal set is split into various cumulative sub-proposals, such that if the
SACC disagrees with Donegan et al. (2011)’s treatment or wishes to adopt some
other arrangement, it can stop at an earlier or later stage of limb separation
and still come up with a new taxonomy.
A: Split veraepacis (with dumicola,
rosenbergi, buckleyi, acrophites, aenea and olivacea),
from turdina (with wallacii, amazonum, intermedia, steinbachi,
stenorhyncha and panamensis). Taxa dumicola (of
the veraepacis group) and stenorhyncha (sister to eastern
races for which the name turdina is senior) are sympatric in Central
Panama (Ridgely & Gwynne 1989) and differ in their voice and plumage. Recordings of the two vocal types that these
names represent by Ken Allaire, Mike Nelson and others from Panama (of which
sonograms were presented in Donegan et al. 2011) overlap geographically,
confirming sympatry or elevational parapatry.
According to recordist notes, the two do not respond to playback of one
another. Separately, subspecies aenea
(east slope Ecuador) replaces the Amazonian lowland groups (amazonum)
by elevation in the Andes-Amazon interface.
This split is an easy one under a BSC approach, mandated by two
instances of sympatry, but it produces two vocally non-cohesive species with
weird distributions, one of which is polyphyletic. It is strongly recommended that this proposal
be accepted as a starter, in the context of the next following sub-proposals.
B. Split stenorhyncha
(with panamensis) from turdina (with wallacii, amazonum,
steinbachi and intermedia). These
populations are allopatric sister populations. Nonetheless, this is
a straightforward split in light of them having perhaps the strongest pairwise
vocal differences of any two groups, which are equivalent to those between
sympatric Schiffornis. This
proposal, if accepted, clears up some of the strange distribution caused by A
and deals with vocal non-cohesiveness of the eastern group. The plumage differences between the three
species split by proposals A and B together are also very strong, as
illustrated by photographs of examples of the three taxa from Colombia in
Donegan et al. (2011). Daniel Cadena fairly
criticised Nyári (2007)’s split of this taxon on
account of it not being based on recordings from different biogeographic
regions within the range of stenorhyncha (including ‘panamensis’). In
Donegan et al. (2011), we presented or studied sonograms of birds from near the
type locality of stenorhyncha (Falcon, Venezuela), the Merida Andes
(including near the southernmost extent of the East slope population), the
Magdalena valley, Serranía de San Lucas (Cauca valley border, it does not go
further south in this region) and eastern Panama (near the type locality of “panamensis”),
confirming the consistency of the song throughout the range of Nyári (2007)’s
proposed species stenorhyncha.
--- These first two proposals come
very highly recommended for acceptance and should be regarded as
uncontroversial under any species concept. There now follow two
further splits of allopatric populations which Nyári proposed making in his
SACC proposal and with which Donegan et al. (2011) agreed. ---
C. Split aenea (monotypic)
from veraepacis (with dumicola, rosenbergi, buckleyi, acrolophites; and olivacea if D
fails). S. aenea is the Andean East slope population in
Ecuador and Peru. It may also extend in range into southern
Colombia, although there are no records there yet. The two
populations subject to proposal C are apparently allopatric sister populations
which straddle the Andes. When split,
they appear as mutually monophyletic (c.3% mtDNA difference). Rejecting this split does not therefore produce
polyphyly or paraphyly. S. aenea is
however vocally rather different from veraepacis, leading to
various authors such as Ridgely & Tudor (2001) and Krabbe & Nilsson
(2003) noting that more than one species may be involved (see sonograms in
Donegan et al. 2011). The differences
are not as great as those shown by stenorhyncha (Proposal B), with
various of the note shapes of the aenea song having equivalents in a
different order in the songs given by the veraepacis group, but the
differences in note shape or order of note shape are consistent and
diagnosable. We preferred to spit aenea,
based on vocal differences, molecular data, and their distributions - which
straddle the Andes in a very high part of the mountain range. Taken
together, these factors put the burden of proof on those who would
have these two lumped.
D. Split olivacea (monotypic)
from veraepacis (with dumicola, rosenbergi, buckleyi and acrolophites; and aenea if C fails). This is the troubling Guianan shield
population. This proposed split was subject to a differing treatment
by Nyári (2007) in his BSC interpretation (lumped) versus his SACC proposal and
PSC interpretation (split). Olivacea is
vocally very similar to the veraepacis group, with no differences
elucidated by Nyári (2007). In Donegan et al. (2011), we noted small
differences in the extent of the upturn of the main note. In the
previous proposal, there was some speculation as to whether the vocal
similarities here are a result of limited divergence or convergence, although
most committee members seemed in favour of splitting
this taxon. It is basal to all other
current turdina in the Nyári (2007) phylogeny, showing 9%+ mtDNA
differentiation from all other taxa. In Donegan et al. (2011), we
presented additional information suggesting that olivacea is indeed the
correct name for this population, as provisionally treated by Nyári
(2007). Not splitting olivacea produces a veraepacis group
which is polyphyletic and which has a strange distribution. Because Proposal A should not be regarded as
optional (and B and C are strongly recommended), it would be reasonable also to
make this split.
--- We went this far in Donegan et
al. (2011) and did not adopt any further splits. ----
E. Split amazonum (with wallacii)
from turdina (with intermedia and steinbachi). This is the “North Amazon vs. South Amazon
and Atlantic forest” split that Nyári (2007) proposed. There is
clearly vocal variation in the southern part of the greater ‘turdina’
range, but this split raises various difficulties, some of which were discussed
by Doug Stotz and Van Remsen as being unfavourable
factors towards adopting the treatment in the previous proposal. Further research indicates that turdina in
the subspecies sense (South Atlantic forest) resembles amazonum (North
Amazon) vocally; whilst intermedia (North Atlantic forest)
generally resembles assumed steinbachi (south Amazon of Bolivia to Peru)
vocally. All these eastern and southern populations are monophyletic
when taken together. Their songs are all generally comprised of
longer notes than the other species, differing among one another in the shapes
of up or down-turns at the start of end of particular notes (see sonograms in
Donegan et al. 2011). These vocal differences exceed those shown by olivacea
but do not reach the differentiation shown by aenea. Given the scope of our paper (Colombia), a
detailed examination of the Bolivian and Brazilian types, their localities and
sound recordings on different sides of major Amazonian rivers was out of scope,
but could be recommended for further research.
This split or other possible treatments for the southern populations may
be warranted but lumping them does not cause paraphyly or polyphyly, nor does
it produce a vocally uncohesive group or preclude
further studies from taking place. We did not recommend adopting
this split for the time being but further research is clearly warranted.
--- Nyári (2007) went this far and
did not adopt any further splits. ---
F. A further possible alternative
for the Eastern taxa based on tentative vocal data would be to split turdina
(with wallacii and amazonum) from intermedia (with steinbachi).
This produces two species of strange distribution and it is unknown how this
would hang with molecular data, owing to the lack of sampled individuals from
very close to the type localities of some of these names in Nyári
(2007). We did not take this step, but SACC members with greater
familiarity with southern Amazonian and Atlantic forest birds may wish to
comment on this option or consider it, for completeness, as an alternative to
E.
G. Split veraepacis (with
dumicola) from rosenbergi (with buckleyi and acrophites). Proposals
A-C, if accepted, result in veraepacis including two disjunct
populations, one in the Chocó-Tumbes and another broadly in Central
America. The ranges of the two are bisected in the Tacarcuna region
to southern/eastern Panama by that of stenorhyncha. The veraepacis and rosenbergi groups
are apparently mutually monophyletic, although with low molecular differentiation
(0.8% mtDNA) and with small vocal differences. This would be a
possible split under some species concepts (e.g. PSC) but we did not adopt
it. Tentative differences in secondary calls (based on only a single
Central American recording of the secondary song) should be regarded as a
matter for further research. As with the possible Amazonian splits,
not adopting this treatment does not preclude further studies of these birds.
Recommendation: A
resolute YES to A and B; YES to C and D for the reasons set out in Donegan et al.
(2011) and Nyári (2007). NO to E, F and
G for the time being, with a note that further research could shed light on
variation among these populations and that other splits may be warranted in the
future.
English names: If any of
these proposals pass, then the English names suggested by Arpad Nyári in
Proposal 327 (see above) would be adopted. If anyone prefers a
different vernacular name for a narrower turdina, then they
can raise a separate proposal on that issue.
References:
Donegan, T.M., Quevedo, A., McMullan, M. & Salaman, P.
2011. Revision of the status of bird species occurring or reported
in Colombia 2011. Conservación -Colombiana 15: 4-21.
Nyári, Á. S. 2007. Phylogeographic patterns, molecular and vocal
differentiation, and species limits in Schiffornis turdina (Aves). Molecular
Phylogenetics & Evolution 44: 154-164.
Other references are cited in these
papers.
Thomas Donegan, October 2011
=========================================================
Comments from Robbins: “YES to
subproposals A (veraepacis), B (stenorhyncha), C (aenea),
and D (olivacea). Nyari’s genetic and preliminary vocal data clearly
established that these taxa should be elevated to species level; Donegan et
al.’s (2011) more in-depth vocal analyses corroborated those results. Undoubtedly,
recognition of additional species will be warranted when more detailed
information becomes available.”
Comments from Stiles: “This
proposal would split Schiffornis turdina into at least four
species, based primarily upon data from the genetic analysis of Nyári and a
more detailed analysis of vocalizations by Donegan. The latter are a
definite step forward and incline me to agree with the proposal, although given
the abundant material available, I would have felt more comfortable if statistical
analyses of the vocalizations had been performed. However, with the
data at hand I agree that the burden of proof has now shifted onto those who
would retain a single species. I have now had a chance to examine the Colombian
material here and have obtained information on the plumage differences of at
least the Colombian taxa, and this leaves me with strong doubts regarding the
English names proposed by Nyári – given the rather subtle differences between
most taxa and the uncertainty regarding the limits of some distributions, I
feel that appropriate and descriptive English names may be important, and will
make a series of suggestions below (which might warrant a separate proposal).
For now, regarding the splits proposed by Donegan:
A. Split
the veraepacis group from a broad turdina: YES. The sympatry of
the two groups in central Panamá, plus differences in vocalizations and
evidence that the two do not respond to each other’s songs makes this split
mandatory.
B. Split
the eastern amazonum group from the northern stenorhyncha group:
YES. Both the genetic data and information from vocalizations, as well as
biogeography, make this split logical and desirable.
C. Split aenea
from the veraepacis
group: YES. Although the genetic data are not quite as definitive,
both vocalizations and biogeography seem better addressed by splitting.
D. Split olivacea
of the Guyana Shield from the veraepacis group: YES. This split will
avoid massive polyphyly in the genus as a whole and makes good biogeographical
sense as well.
“I agree with Donegan that although
some further splits could be made, especially in the amazonum group,
more data are required. The split of rosenbergi-acrolphites
from veraepacis has no genetic backing and mainly reflects the gap in
distributions, which might be better explained by historical factors. For now, the four splits suggested are
sufficient and desirable.
“Now, for the messy part: English
names. Because the splits have as yet
not been “officially” adopted, it seems appropriate to make these suggestions
now. To begin with, I feel strongly that the name “Brown
Schiffornis” for the veraepacis group (species) is singularly
inappropriate. The two Colombian races (acrolophites and rosenbergi) are much
the greenest of all the taxa. By far the brownest of
all is stenorhyncha (which is also not the
“slenderest-billed”; that distinction belongs to amazonum). Hence, I would propose that the name “Brown
Schiffornis” be applied to stenorhyncha (or “Brownish Schiffornis” if
one wishes to avoid confusion with Nyari’s
names). “Greenish Schiffornis” could
then be applied to veraepacis. I
make this latter suggestion a bit tentatively, as I do not have material of the
northern races of the latter for direct comparison, although my description and
the plate in the Costa Rican guide (as well as the descriptions in Ridgway)
emphasize olive-green to olive-brown tones. (The name “olivaceous” would also
be appropriate, but is perhaps best reserved for olivacea of
the Guyana Shield – although for the latter “Guianan Schiffornis” would also be
appropriate). Aside from its overall brownish coloration, the most
trenchant plumage characters of stenorhyncha are the decidedly rufescent
color of the wings and the sharp division of the brownish to olive-brown breast
band and the grayish-olive lower breast and belly; it is also the largest
taxon. Hence “Rufous-winged” or
“Grayish-bellied” would not be inappropriate for this taxon. I note
here that none of our series of stenorhyncha show the clear gray belly
of the bird in Donegan’s photo: given the yellowish coloration of the basal tomia and gape, I suspect that his bird was young – I
suspect that young birds in this genus in general are brighter and more contrasty than adults, though few of our specimens are
reliably aged. Actually, the belly in amazonum is also
grayish olive and in some is grayer than in most stenorhyncha, although
the contrast with the breast is not nearly so sharp. The wing in amazonum is a darker,
duller brown than in stenorhyncha so “Brown-winged Schiffornis” would
emphasize this difference, but I think that “Amazonian Schiffornis” is
certainly simpler and appropriate, and could be kept for amazonum should
this group be split further - although such a split (or splits) seem
problematic for the present.
Comments from Stotz: “YES on
subproposals A, B, C, and D. NO on subproposals E, F, and G. I am
much more comfortable with this proposal than the previous
proposal. We will probably have to split other taxa farther down the
line, but this is a reasonable first step on this complicated
group. I agree with Gary that we need to think about English
names. However, his suggestion of “Greenish” for veraepacis
won’t work. Greenish Schiffornis is the
name of Schiffornis virescensof SE Brazil. I think that it would be a
mistake to use Olivaceous for veraepacis with S. olivaceus being
one of the names. So I don’t have a good alternative in mind, but I
agree with Gary that Brown would not be a great choice. I would go
for Brownish for stenorhyncha, and while I am okay with Olivaceous for S.
olivaceus, I think we would be better served to adopt a geographic modifier
Guianan for that species. One further issue is a name for the reduced
turdina. Given the complications in that group, and how much
of the turdina (sensu lato) has been carved off from
it. I think we absolutely have to have an alternate English name for
this new turdina. Unfortunately,
I have not come up with a great answer. These are really dull
birds. My only thought is Southern Schiffornis.”
Comments from Pérez: “YES to
subproposals A, B, C, and D. I think molecular, vocal and distributional data
support this awaited treatment for S. turdina. NO to subproposals E, F
and G; more in-depth treatments, as suggested by Donegan et al. (2011), would
likely provide information for further splitting.”
Comments from Jaramillo: “YES –
accept A, B, C, and D. I am not comfortable going further with it, particularly
as vocal data are relatively common and further separations require a higher
level of scrutiny. Having said this, once we determine which forms the
committee has decided to split off, or not, I think we need a separate simple
proposal on the English names.”
Comments from Nores: “YES to
subproposals A (veraepacis), B (stenorhyncha), C (aenea),
and D (olivacea). I consider that the molecular and vocal data
support this treatment. However, I did not find either in the proposal or
the Nyári´s paper a clear relationship
between the new species and the regions 1-7 of the phylogeographic tree of
Nyári. How much easier would have been to interpret the Nyári´s
tree if he would have put the name of the subspecies or species next to the name of the region.
Comments from Remsen: “YES to
subproposals A (veraepacis), B (stenorhyncha), C (aenea),
and D (olivacea). Echoing the comments of others, there is
good evidence for at least 5 species, and more will likely come from additional
analyses. By the way, I strongly agree with Manuel’s comment on the
poor labeling in Nyári´s tree – just one more
example of how poorly edited MPE is.
“English
names are a real problem. Ridgway and Hellmayr both used
“Olivaceous” for S. olivacea, so I would favor retaining that
one. Gary’s comment on “Brown” for veraepacis is correct – “Brown”
is perhaps the worst name possible for this species, even though used by
Ridgway and Hellmayr. Ridgway used
“Russet” for stenorhyncha, but I do think Gary’s name is better. Hellmayr used “Slender-billed”, but no reason
to perpetuate that if inaccurate. Also, Doug’s comments are also
correct – “Greenish” is not available, and we really cannot retain
“Thrush-like” for a dramatically diminished S. turdina (and besides,
it’s a poor name, species epithet not withstanding). So, I am installing some temporary English
names based on Gary’s recommendations and will be appointing someone to make a
formal proposal to examine carefully the English names before they get any
traction.”