Proposal (866) to South American Classification Committee
Change
the scientific name of Chapada Flycatcher (yes, again)
Background: Chapada Flycatcher
came to our attention when it was described as Suiriri islerorum by Zimmer et al. (2001). As later was documented
by Kirwan et al. (2014), however, islerorum
is a junior synonym of Elaenea affinis
Burmeister 1856. This issue was considered several years ago by SACC (Proposal 671), as a result of which
the SACC scientific name for Chapada Flycatcher became Suiriri affinis.
Mentioned
in passing (page 75) in the 2001 paper was the observation that
"preliminary molecular analyses of tissue samples indicates that S. islerorum [= S. affinis] is strongly differentiated genetically from both S. s. affinis [now Suiriri suiriri burmeisteri] and S. s. bahiae (J. Bates pers. comm.). Those results will be
presented elsewhere as part of an overview of genetic diversity in Suiriri".
New information: Unfortunately Bates
never published an overview of genetic diversity in Suiriri. Eventually, however, another research group tackled this issue.
Lopes et al. (2018) documented that indeed "Suiriri" affinis and
Suiriri suiriri are "strongly
differentiated genetically":
Their
phylogenetic analysis, based on DNA sequence data from mitochondrial and
nuclear genes, indicates that Suiriri
suiriri is an elaenine flycatcher, consistent with standard classifications
(e.g., Traylor 1979, Dickinson and Christidis 2014) and with other recent
phylogenies (e.g., Ohlson et al. 2008, Tello et al. 2009), whereas "Suiriri" affinis is deep within the fluvicoline group.
In
the apparent absence of an available name (and I hope that they did due
diligence here), Lopes et al. proposed a new genus, Guyramemua, with Elaenea
affinis Burmeister 1856 as the type species.
Analysis: Clearly affinis and suiriri are not congeneric. We have two options. Option One is to transfer
to Chapada Flycatcher to Guyramemua,
which is a bit of a mouthful, but is an available name. Guyramemua
is neuter, so the spelling of the species name must change from affinis to affine.
The
second option, as pointed out by Santiago Claramunt, would be to transfer
Chapada Flycatcher from Suiriri to Sublegatus. In this case, the spelling
of the species epithet would not change.
Recommendation: I recommend Option One,
to change the scientific name of Chapada Flycatcher from Suiriri affinis to Guyramemua
affine. I recognize the relatively
short branch length from Chapada Flycatcher to Sublegatus. But, as was
described in Zimmer et al. (2001), Chapada Flycatcher has a distinctive
wing-wagging display that is unusual (although not unique) among tyrannids;
placing it in Sublegatus, in which
such a display seems to be lacking, serves to downplay one of the more
interesting attributes of Chapada Flycatcher. That said, the most important task here for
SACC is simply to get Chapada Flycatcher out of Suiriri, where it does not belong.
Literature Cited:
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.
Kirwan,
G.M., F.D. Steinheimer, M.A. Raposo, and K.J. Zimmer. 2014. Nomenclatural
corrections, neotype designation and new subspecies description in the genus Suiriri (Aves: Passeriformes:
Tyrannidae). Zootaxa 3784: 224-240. https://doi.org/10.11646/zootaxa.3784.3.2
Lopes,
L.E., A.V. Chaves, M.M. de Aquino, L.F. Silveira, and F.R. dos Santos. 2018.
The striking polyphyly of Suiriri:
convergent evolution and social mimicry in two cryptic Neotropical birds.
Journal of Zoological Systematics and Evolutionary Research 56: 270-279. https:/doi.org/10.1111/jzs.12200
Ohlson,
J.I., J. Fjeldså, and P.G.P. Ericson. 2008. Tyrant flycatchers coming out in
the open: phylogeny and ecological radiation of Tyrannidae (Aves,
Passeriformes). Zoologica Scripta 37: 315–335. https://doi.org/10.1111/j.1463-6409.2008.00325.x
Tello,
J.G., R.G. Moyle, D.J. Marchese, and J. Cracraft. 2009. Phylogeny and
phylogenetic classification of the tyrant flycatchers, cotingas, manakins, and
their allies (Aves: Tyrannides). Cladistics 25: 429-467. https://doi.org/10.1111/j.1096-0031.2009.00254.x
Traylor,
M.A., Jr. 1979. Family Tyrannidae,
tyrant flycatchers.
Pages 1-299 in M.A. Traylor, Jr. (editor), Check-list of birds of the world.
Volume 8. Museum of Comparative Zoology, Cambridge, Massachusetts.
Zimmer,
K.J., A. Whittaker, and D.C. Oren. 2001. A cryptic new species
of flycatcher (Tyrannidae: Suiriri)
from the Cerrado region of central South America. Auk 118: 56–78.
Tom Schulenberg, July
2020 (with minor subsequent revisions to original proposal’s Analysis and
Recommendations sections to address Claramunt et al.’s concerns)
Comments
from Remsen: YES. I
don’t think anyone saw this one coming!
But that’s what the DNA says, and as Tom pointed out, assuming due
diligence has been performed on available names, a new genus is required.”
Comments
from Stiles:
“YES. Required
by the genetic data.”
Comments from Areta: “YES. Putting affinis in Sublegatus
is not a reasonable choice, given the marked differences in displays, behavior
and vocal structure.”
Comments
from Claramunt:
“NO. Very
interesting and robust phylogenetic result, and very interesting biological
explanation. However, regarding the
taxonomy, the most obvious option should be to transfer the Chapada Flycatcher
to Sublegatus, not to create a monotypic genus. From the evidence presented, it seems to me
that affinis fits nicely in Sublegatus, which is an already
smallish and homogeneous genus. This is
apparent from the evidence shown in the paper itself, discussing the
similarities of affinis and Sublegatus, note the stubby beak
typical of Sublegatus (see the
photographs in Fig. 1). Of course affinis is not identical to the
other Sublegatus -- it’s a different species, somewhat modified by
social mimicry -- but I think it fits in Sublegatus nicely. Branch
lengths seem within the range of other genera. In sum, I think the cons
outweigh the pros; I don’t see the need to create a monotypic genus and
introduce a new (and difficult to pronounce) name in the already complex
taxonomy of the Tyrannidae.”
Comments from Robbins: “NO. Clearly affinis needs a new generic
allocation; however, I vote No, for the sole reason of having to create yet
another monotypic genus. As Santiago
suggested, I support transferring affinis to Sublegatus. If we can place credence in comparative node
depth and genetic divergence, putting affinis in Sublegatus would
be on par with how Myiophobus is defined (see figure in the proposal
from Lopes et al.).”
Additional comments from Remsen: Given Santiago’s comments
and Mark’s comment on node depth, I withdraw my Yes vote until better
justification for the new genus is presented.
Comments from Stiles: “NO. Yes to separating affinis
from Suiriri; but I agree with Santiago that the genetic evidence is
also compatible with including it in Sublegatus.”
Comments from Bonaccorso: “NO. Completely agree with Santiago
and Mark. No need for another monotypic genus within Tyrannidae, as affinis
can fit nicely within Sublegatus.”
Comments from Zimmer: “YES. It has been clear to me, ever since John
Bates did the original molecular analysis on the 10 specimens of Suiriri
"islerorum" (= affinis) and the 10 specimens of S.
s. affinis (= burmeisteri) that we collected from the
Chapada dos Guimarães region of Mato Grosso, Brazil, that "islerorum"
(= affinis) would require a new generic allocation. When John called to give me the results, his
response to my question of "Well, does your analysis support our contention
that there are two species [of Suiriri] involved?", was to say, ‘Not only are there 2 species, but they don't even belong in the
same genus!’. Off the top of my head,
I believe he found 16% sequence divergence between "islerorum"
(= affinis) and "affinis" (= burmeisteri), and
the closest thing he could find to "islerorum" was Sublegatus
(8% sequence divergence). So, before
even publishing our results describing "islerorum" (= affinis)
as a species distinct from the rest of Suiriri, we knew that it would
need to be reallocated to another genus. That we did not do so at the
time, was due partly to the desire to prioritize the findings regarding
species-limits, and partly because the genetic work underpinning the need for
generic reallocation was part of a much larger genetic study that John and his
colleagues were working on. So, yes, the need for generic reallocation of
Suiriri affinis is clear.
“I disagree with Santiago's contention that the "most obvious
option should be to transfer the Chapada Flycatcher to Sublegatus, not
to create a monotypic genus." In my
opinion, It does not "fit nicely in Sublegatus", which, as
Santiago notes, is "an already smallish and homogeneous genus." Aside from the general plumage pattern of
grayish chest, yellowish belly, brownish-olive upperparts, and buffy wingbars
(a general pattern not unique by any means to Sublegatus, and, in fact,
shared with Elaenia, Myiarchus, Suiriri, and gobs of
tyrannulets spread through various genera), the only morphological character
that I can see that could be considered as uniting S. affinis
with Sublegatus is the stubby bill (mentioned by Santiago). I think it's fairly well established that bill
morphology is a very plastic character, subject to extreme selective pressure,
and should not be given undue weight as a taxonomic character. Sticking with plumage characters, there is not
one described taxon in Sublegatus that has either the boldly contrasting
pale rump, the very blackish tail, or the broad, contrasting, buffy terminal
band to the tip of the tail, let alone the entire suite of these plumage
characters that distinguish the Chapada Flycatcher. More importantly, the vocal repertoire of
Chapada Flycatcher is off-the-charts different from that of any of the named
species of Sublegatus (all of which, are fairly similar to one another,
particularly arenarum and modestus), and the habitual duetting
behavior of Chapada Flycatcher, accompanied as it is by exaggerated physical
displays, themselves stereotypical both to species and sex, is something that
is not even approached by anything that I've seen any Sublegatus do. As for the question of comparative node depth
and genetic divergence as seen in Lopes et al. (2018), it also looks as if the
branch lengths between affinis and Sublegatus are not that
different from those between Alectrurus and Gubernetes, and the
node depth of affinis + Sublegatus would be comparable to that of
Empidonomus + Tyrannus, so that does little to budge me off my
position that Chapada Flycatcher is a real outlier relative to the small and
homogeneous grouping of Sublegatus as currently constituted.
“Frankly, I don't see much difference between this case and the
one being considered in Proposal #867 (concerning reallocation of "Thraupis/Pipraeidea"
bonariensis to its own monotypic genus), which everyone seems to
support, other than that adoption of that proposal would leave us with two
sister-species, each placed in monotypic genera, whereas, adoption of Proposal
#866 would leave us with sister genera, one of which contains 3
morphologically, vocally and behaviorally homogeneous species, and the other of
which is monotypic and distinct from its sister genus in plumage,
vocalizations, and complex display behaviors.”
Comments
from Jaramillo:
“YES, This is a deep branch, also there are some
major differences in voice/behavior between Chapada and Sublegatus. It
could be argued that affinis fits nicely in Sublegatus based on
structure, but then again it fit nicely in with Suiriri as well! So that
is not much of an argument to me. The deep branch and behavioral, vocal
differences lead me to vote yes on Guyramemua.”
Additional
comments from Robbins: “I think invoking that Chapada Flycatcher as a mimic/model
in plumage morphology is a stretch. First
of all, affinis looks very similar to Sublegatus: dorsally, wing
bars, ventrally and the stubby bill – compare photos of affinis (a
number are online) with Sublegatus modestus. Yes, affinis
is larger, so what? The fact that affinis
looks very similar to Sublegatus might because they share a common
ancestor! Nonetheless, invoking whatever
characters to justify a new genus of birds that are clearly extant sister taxa
becomes debatable when one looks at examples such as the genera Setophaga
(the diversity of plumage, ecology, voice is striking in that genus; recall
that members of that genus were once placed in 4 different genera as a result
of the dramatic differences in all aspects of their biology) and Buteo –
there are many other examples.
“Again,
one of my points is in that same group of flycatchers, Myiophobus has
comparative node depth and genetic divergence.
“What
I have taken from the past 10-15 years of genetic data sets, which have become
the underpinnings of our taxonomy, is that differences in morphology, voice,
habitats, etc. are quite limited in defining relationships except in cases of
species limits. Clearly, defining genera
is highly subjective, so there is no right or wrong.
Additional
comments from Zimmer:
“Interesting to read the latest round of comments
regarding whether to recognize a monotypic genus Guyramemua for the
reallocation of Suiriri affinis versus moving it to Sublegatus,
and, more generally, on the whole question of the desirability of monotypic
genera. There have been lots of points
raised by those who favor the reallocation to Sublegatus, and I would
like to address some of them, both with respect to the specifics of this
Proposal, and from a more generalized, philosophical perspective. My apologies in advance for the length of my
remarks!
“Mark states that “Clearly, defining genera is highly subjective,
so there is no right or wrong.” I agree with this statement 100%. Once the condition of monophyly has been met
(as in the present case), whether to recognize one genus or two becomes a
matter of taste. I’ve made no secret of
my preference for recognizing genera that are more narrowly defined and
internally cohesive (morphologically, vocally and ecologically), but I realize
that not everyone shares that preference. Several members have argued against
creating monotypic genera, on the grounds that these are, somehow, not informative.
I would counter this by echoing Vitor’s comments on the topic, which, in my opinion, were
spot-on. It all depends on what sort of
information one looks to a working classification for. If all you are interested in is the phylogeny,
then go to the phylogeny! Mark notes
that “What I have taken from the past 10-15 years of genetic data sets, which
have become the underpinnings of our taxonomy, is that differences in
morphology, voice, habitats, etc. are quite limited in defining relationships
except in cases of species limits.” To
a certain extent, I agree with this assertion too. But then, what are we to do with this? If,
as Van suggests, “that a lot of the subjectivity would be removed by focusing
more on comparative node depths etc. as a proxy for time” and that such an
approach would be better “than the unrepeatable artsy subjectivity we all use
in drawing generic boundaries within a monophyletic group”, my question would
be “So what kind of additional information, aside from what is already evident
in the phylogeny, would we be imparting by drawing generic boundaries based
upon comparative node depth?” Or, as
Vitor put it: “So phylogenetics is more
important than the biology of the species?”
“I agree with Van that “each of us has a different idea of the
subjective limits of generic boundaries” and that “those ideas often depend on
how familiar one is with the group”, but I’m not sure what he was
getting at when he added “the greater the familiarity, the greater weight to
the differences, generally”. Was
this an expression that more weight should be given to the evaluation of
differences by those with greater familiarity, or, was it implying that there
was inherent bias towards recognizing differences by those with greater
familiarity? If the latter, I would push
back by suggesting that the greater the familiarity one has with all of the
taxa involved, the more objectively one can evaluate and contextualize not only
the differences between taxa, but also the similarities. In the case of the Chapada Flycatcher, Van’s
observation would seem to ring true, because all of the people weighing in who
know both S. affinis and Sublegatus in life seem to recognize
just how different they are, and, consequently, favor the Guyramemua option.
However, I would argue that the bias in
this scenario lies with those who don’t know Chapada Flycatcher in life, and
who, without that experience to draw upon, necessarily, revert to superficial,
coarse-grained similarities/differences in plumage, which, as the genetics have
shown us over and over again, particularly among suboscine passerines, is much
less indicative of relationships than similarities/differences in vocalizations
and biology/ecology.
“In this context, I would urge everyone to review the positions
taken over the recognition of Cyanophonia in Proposal #856. Some among us expressed the desirability of
resurrecting that genus (despite comparatively short node lengths), based on Cyanophonia
being “phenotypically and genetically distinct” (from Chlorophonia);
that Cyanophonia is “monophyletic, highly supported and clearly
diagnosable by plumage”; that such a path would result in a “simple and
descriptive classification”; and, that to do otherwise (i.e. transfer the Cyanophonia
species into Chlorophonia), would result in a genus (Chlorophonia)
that “would no longer be diagnosable.” Yet, the same members who made
these arguments supporting the restoration of Cyanophonia, favor sinking
the Chapada Flycatcher into Sublegatus, despite the fact that the
Chapada Flycatcher is also “phenotypically and genetically distinct”,
“monophyletic”, “highly supported, and clearly diagnosable by plumage”, and,
that placing it in its own genus would result in “a simple and descriptive
classification”, whereas, reallocating it to Sublegatus would result in
a slightly simpler classification but one which, would be, arguably, less
descriptive, and which, I would contend, would make Sublegatus so
heterogeneous as to render it undiagnosable. There are only two rationales that I can see
for the conflicting approaches taken to these two cases: 1) an underlying,
philosophical distaste for monotypic genera; and/or 2) lack of appreciation for
just how different affinis is, relative to Sublegatus. I understand the philosophical differences
over monotypic genera (although I would reference Vitor’s
defense of monotypic genera, which makes the case better than I could), but,
again, some of the same members who are so opposed to erecting a monotypic
genus for the Chapada Flycatcher, had no such qualms in recognizing not one,
but two monotypic genera, when it came to removing Blue-and-yellow Tanager from
Pipraeidea and placing it in Rauenia (a move that I
wholeheartedly supported as well). The
primary distinction between these cases (Cyanophonia and Pipraeidea/Rauenia)
and Guyramemua that I can see, is that the latter involves a group in
which plumage is evolutionarily conservative (rendering differences between
taxa subtle), whereas the other two examples both involve groups in which
plumage is anything but conservative, and in which plumage differences are
blatantly obvious in photographs, even to those unfamiliar with the various
taxa in life.
“Assuming that we are all in agreement that defining generic
boundaries is subjective, and that there is no right or wrong answer, then, it
seems to me that Proposal #866 should be structured with 2 distinct parts: #866A, remove Chapada Flycatcher from Suiriri
(which I think, everyone agrees with); and #866B, erect a monotypic genus. However, I don’t think that this should be
structured in a way that moving affinis to Sublegatus becomes
the default option if we fail to get the votes needed to pass #866B. Transfer to Sublegatus should require
a separate proposal, requiring the same 2/3s majority vote for passage. To do otherwise, would result in tipping the
scales in a way that gives less weight to the votes of the members who actually
know the involved taxa in life. Nor do I
agree, as Santiago seems to suggest in his response to Vitor, that the burden
of proof in this debate falls on those who contend that the Chapada Flycatcher
is too different to include in Sublegatus. Starting with Zimmer et al. (2001), there
have been some very detailed published accounts detailing not only the
morphological characters that diagnose Chapada Flycatcher, but also
spectrographic evidence of the calls, songs and duets, as well as detailed
behavioral descriptions, including the sexually stereotypic physical displays
associated with the duets. Although the
bulk of these discussions were focused on presenting these distinctions
relative to Suiriri, I did include a comparative discussion of Sublegatus
in my diagnosis of Chapada Flycatcher. All
anyone lacking field experience with Chapada Flycatcher has to do to see for
themselves the distinctiveness of this taxon relative to Sublegatus, is
to go to the WikiAves on-line photo archive and search “Suiriri affinis”
– you will find page after page after page of photos, including gobs of
spectacular ones of wildly displaying birds showing off the contrastingly pale
yellow rump, the much blacker tail, and the contrasting pale terminal band to
the tail, all features lacking in all 3 currently recognized species of Sublegatus,
and all features which, not coincidentally I imagine, are prominently featured
in the wing-and-tail-flapping displays of Chapada Flycatcher. Then, while still on WikiAves, use the search
bar to go to the pages for the various members of Sublegatus. The distinctions should be obvious. Scrub-Flycatchers look like miniature Elaenias
to me – the whole jizz is different from Chapada Flycatcher, which, no
surprise, gives off a Suiriri-type feel, which helps explain why it was
erroneously placed in the incorrect species, genus, and even subfamily for so
long, without detection. Similarly, it
is not difficult to go to an on-line sound archive such as Xeno-Canto and
compare vocalizations of Chapada Flycatcher to those of the various Sublegatus species. I guess what I’m saying, is that the
“quantitative and comparative evidence” is abundant, published, and out there
(in the public sphere), and that the burden to provide it (beyond citation of
sources for that evidence) should not be incumbent on either the author of the
Proposal (in this case, Tom Schulenberg), or, on those of us supporting the Guyramemua
option, at least not any more so than it should be incumbent on members
supporting the expanded Sublegatus option to provide evidence supporting
their position. The default position for
not being sufficiently familiar with the evidence should be
“abstention/recusal” from voting, not a “NO” vote.
“Again, the burden of proof should be at least as high for those
wanting to sink affinis into Sublegatus. As Vitor stated:
“So, if SACC members do believe Chapada Flycatcher belongs in Sublegatus,
I plea all voters do that based on some rationale that justify recognizing all
4 species as a unit, despite the many differences highlighted by Kevin -- and
not based on "I don't like monotypic genera".
“Many of us, when evaluating species-limits, employ the “yardstick
approach” in our decision-making process, using degree of morphological, vocal,
behavioral and genetic difference between other recognized species in the same
genus to infer the significance of differences in the taxon
being evaluated. It strikes me that this
is the same technique that we would be using when focusing on comparative node
depths in related groups to delimit genera. But why not apply the
comparative yardstick approach to the whole suite of morphological, vocal,
behavioral and genetic data in making decisions about delimiting genera within
monophyletic groups? Node depth, as a
proxy for time, is something that can be “seen” by birders or ornithologists
only when looking at a tree diagram. How
intuitive, descriptive, or utilitarian is a classification defined by things
that can’t be observed on the living bird, particularly when these are in
opposition to things such as morphology, voice, and behavior that are obvious
to the observer? Because, there is no
right or wrong answer, why not have a taxonomy informed by genetic data, and
adhering to principles of monophyly, that reflects what can be observed in the
living birds, instead of prioritizing the abstract (node-depth = time)?
“I would challenge everyone advocating for placing affinis in
Sublegatus to look at the morphological, vocal, behavioral and genetic
distinctions between the three species of Sublegatus as currently
constituted, and then compare that “yardstick” to the differences between affinis
and any of the other three species. Then, explain to me how you would diagnose the
expanded genus of Sublegatus + affinis? I fully understand that there are all kinds of
precedent for incorporating some very different species within the same genus. Mark invoked the example of the morphological,
vocal and ecological diversity encompassed within Setophaga as an
example. But, to my mind, that is a very
different case. Setophaga is a
speciose genus encompassing striking diversity in plumage, vocalizations and
ecology, whose constituent species were previously spread across four genera. Even before so many species from those genera
were folded into Setophaga, there was a striking amount of within-genus
variation – just look at the amount of variation (morphological, vocal,
ecological) that was included within Dendroica. That example is not even remotely similar in
my opinion to what we see in the present case, in which you are talking about
adding one very different member (an outlier morphologically, vocally, and
behaviorally) to a small, internally cohesive, and extremely homogeneous group.
“Finally (!!!), I would just reiterate, that since neither
approach (monotypic genus for affinis versus expanded Sublegatus)
is inherently more correct than the other, and, since, in the present case,
there is no real argument to be made one way or the other on grounds of
taxonomic stability (i.e. affinis is going to a new genus one way or the
other, and, either we end up erecting a new genus, or, we upend how an existing
genus is diagnosed), that we should not treat an expanded Sublegatus as
the default option to not recognizing Guyramemua, and, instead, treat it
as a separate proposal that would require proponents of that treatment to
support and defend. It strikes me as
irrational, that, in a case where the status quo (in this case, maintaining affinis
within Suiriri) is not a tenable position, and that neither of the two
alternatives on the table are inherently right or wrong, that the default
position should be that favored by members who have no experience with affinis
in life, and who, by their own admission, “have not examined specimens or
comparative evidence”, and are “left in darkness”, especially, when the
recognition of Guyramemua has the support of all of the committee
members and outside advisors who actually know the living bird.”
Comments
from Whitney:
“Van asked that I chime in on the subject of generic
alignment in the Sublegatus clade. First, I completely agree with the sentiments
expressed (most elaborately) by Vítor and Kevin. To summarize: Generic boundaries within a well-supported,
multi-species clade are largely subjective, and, in attempting to draw them as
helpfully or informatively as possible, we should look to the biology of the
species involved, “the living birds,” as Kevin closed his opinion yesterday.
“Although it has not been the subject of concerted phenotypic or
genetic study, Sublegatus is clearly a paraphyletic assemblage, and even
includes (supposedly named) taxa that breed in sympatry; additional taxa may
overlap during austral winter. I’ll take
a shot at four similar-looking, vocally strongly differentiated, BSC
species-level taxa throughout the range from e Panama to nc
Argentina. Chapada Flycatcher is clearly
different from them all, both morphologically and vocally. Behaviorally, it is much more similar,
however, including the wing/tail display. The nominate and some other populations of Sublegatus
do perform a similar display as members of a pair come together, albeit a
“smaller” display — less dramatic and less prolonged — than the display of
Chapada Flycatcher — the point being that there is, in fact, a similar behavior
there, with no assumption of homology (several flycatchers in at least three
subfamilies perform somewhat similar displays!). Obvious differences in size aside, in the
field, I see as many or more similarities than differences between Chapada
Flycatcher and the various Sublegatus. So, on balance, I might lean toward using Sublegatus
for them all, to heighten attention to the fact that they are sisters.
“But I think there is one over-arching reason not to do that — and
that is phylogeography of the clade. The
entire distribution of Chapada Flycatcher is overlapped by sister Sublegatus,
and, moreover, the two occur not just in sympatry, but in syntopy across a vast
area, which points to significantly more ecological divergence than meets the
eye (i.e., there’s a lot to learn about these birds). Although "sisters in
syntopy/sympatry" has not been invoked in making taxonomic judgements, I
suspect it is highly informative, as implied in the description of Herpsilochmus
sellowi (Whitney et al. 2000), which is widely or locally sympatric with
four, syntopic with at least two, Herpsilochmus. We now know it’s sister to Biatas!
“I vote for Guyramemua.”
Additional
Comments from Bonaccorso: “YES. I change my original vote
to accept Guyramemua. The Fluvicolinae are so complex) for so many
reasons) that if using Guyramemua helps to understand evolutionary
change in the group better, so be it.”
Comments from Pacheco: “YES. I vote for Guyramemua.
I know directly the species involved in this “philosophical” case. It may not
be important, but in the field I never made any association between Chapada
Flycatcher and the small homogeneous group of Sublegatus. Display
behavior and vocal repertoire are blatantly and distinctly at odds with what
you see in Sublegatus. This feeling seems to be very strong in those who
know both groups better: Kevin, Bret and Vitor. I agree with them that there is
less harm in treating him in a monotypic genus Guyramemua than sinking
him in Sublegatus.”
Additional
comments from Remsen:
“Given the insistence by those who know the species that the new genus is
warranted, I’ll go back to YES for Guyramemua, but reluctantly.
It’s not that I don’t appreciate those differences, but that I think
it’s more important, biologically, to point out that they must have arisen very
quickly than that they exist.”
Additional
comments from Stiles:
“In view of the comments on behavior and ecology by
those who know the bird in life, which value, I am willing to switch to Guyramemua
for affine (or affinis, whichever is correct).”
Comments by Lane: :”YES. For now I would say best
to place it in Guyramemua. I don't understand this distaste for
monotypic genera, as we can't deny that there are very distinctive monotypic
species in the world, and this is one. From my own experience with Sublegatus
and "Suiriri" affinis, they are not much alike in some key behaviors
and vocalizations (as has been related by Kevin, Bret, and others), so I simply
can't accept lumping the latter into Sublegatus.”
Additional comments from Remsen: “Harvey et al.’s recent
paper in Science confirmed the sister relationship between Guyramemua
and Sublegatus. The
time-calibrated phylogeny predicts that the divergence of the two lineages was
in the middle Pliocene, thus more recent than most tyrannid groups ranked as
separate genera.”