Proposal (966) to South
American Classification Committee
Note from Remsen: This is a proposal submitted to and rejected
(4 to 8) by NACC. Although the comments
are not yet public, the NO voters agreed with the synopsis in the proposal, i.e.,
insufficient data to make formal changes in a complex situation, although
multiple species likely involved.
Split Mionectes olivaceus into two species, M. olivaceus and M. galbinus
Background: Mionectes olivaceus is a small fruit-eating flycatcher with a range
from Costa Rica to eastern Venezuela and Bolivia along lower montane slopes and
nearby lowlands. The species was
described in 1868 by Lawrence from Costa Rica. There are 5 recognized
subspecies all of which were originally described as subspecies of olivaceus.
New Information: Boesman (2016) examined the voices of the
various subspecies of olivaceus and
concluded that there were 4 vocal groups. One was the nominate subspecies, olivaceus, found in eastern Costa Rica
and western Panama. A second consisted of the taxa hederaceus and galbinus.
The subspecies hederaceus occurs from
Veraguas, Panama, south largely on the western side of the Andes to southern
Ecuador whereas galbinus is known
from the Santa Marta Mountains of Colombia.
The third vocal group consists of venezuelanus
from northern Colombia and northern Venezuela and fasciaticollis on east slope of Andes from southern Colombia to
Bolivia. The fourth group is from Santander, Colombia and is not clearly
associated with any of the recognized taxa.
Boesman evaluated the groups using the Tobias (2010) criteria and scored
olivaceus versus the other taxa as 8.
He scored hederaceus/galbinus versus venezuelanus/fasciaticollis as 6.
The
sonograms here are from the Birds of the World account (Fitzpatrick et al
2020). A is nominate canfasciaticollis/ venezuelanus, D is
the Santander population of uncertain subspecies, and E is a single recording
from the far eastern end of the northern Venezuela mountain, which currently
would be assigned to venezuelanus. Recordings of songs from populations in the
Perijá Mountains and Trinidad do not seem to be available.
These
songs are squeaky and extremely high pitched, basically between 8 and 10
thousand MHz I personally cannot hear
the sounds on recordings of nominate olivaceus
(at least through my computer) at all, and am not hearing the other
populations’ vocalizations well. The
literature describes these songs as insect- or hummingbird-like.
Morphological
variation among the five subspecies is minor. The main variation is in the
brightness of the green upperparts, the brightness and tone of yellow on
abdomen, the extent of streaking and paleness of streaking. None of this
variation would be apparent in the field. In del Hoyo and Collar (2016), they
assign some points toward the Tobias criteria score based on plumage. However, I would say, from examining
specimens and the discussion in Fitzpatrick et al (2020), that olivaceus is not at the extreme in any
of the characters varying across the 5 subspecies. It is generally pale and bright, but to my
eye, galbinus is the palest and
brightest of these taxa, whereas hederaceus
is overall the dullest.
At
the time of del Hoyo and Collar (2016) there was no genetic evidence available
for this complex. However, Harvey et al
(2020) examined multiple samples of olivaceus
as well as the other species of Mionectes. In their analysis, Mionectes olivaceus was paraphyletic, with nominate olivaceus, sister to a clade with Mionectes striaticollis and samples
corresponding to galbinus and venezuelanus. M.
striaticollis is a similar species broadly sympatric with olivaceus in South America, overlapping
with the subspecies hederaceus,
fasciaticollis, and venezuelanus.
Recommendation: This is a complicated issue. I think it is very likely there are multiple
species within the current Mionectes
olivaceus. Splitting nominate olivaceus is supported by a distinctive
voice and the genetic evidence that it is not sister to the rest of the
species. If NACC did this, we would add
a species to the overall list, because olivaceus
occurs in Costa Rica and western Panama, and hederaceus representing Mionectes
galbinus occurs in central and eastern Panama. However, it seems likely that there are
multiple species to be recognized in galbinus. Unfortunately, I think we currently lack
sufficient information to define the various species that would be left in galbinus. There has not been genetic analysis done at a
relevant scale for that question, and many populations (including galbinus) do not have recordings in
Xeno-canto or Macauley collections. One vocal group (D from Santander above) has
not been clearly assigned to a named taxon. For NACC, the issue is that the
name galbinus may not be applicable
in the end to the populations in Panama.
This case reminds me of Schiffornis
turdinus for SACC. A proposal to
split in 2007 failed to pass, but with additional data, in 2011 a new proposal
to split Schiffornis turdinus into 5
species did pass.
My
weak recommendation is a NO vote, awaiting further evidence that will allow us to define more
clearly the multiple species that likely make up Mionectes olivaceus.
English
names:
Del Hoyo and Collar (2016) use Olive-streaked Flycatcher for M. olivaceus and retain Olive-striped
Flycatcher M. galbinus. Because the ranges are very uneven in size
with M. galbinus much more widespread
than M. olivaceus, I think the use of
Olive-striped Flycatcher for M. galbinus
is justified under our English name criteria.
Further, given that the splitting up of galbinus into two or more species seems likely eventually, we (or
SACC) would have to coin new names for the daughter species at a later time. I
recommend using Olive-streaked Flycatcher for Mionectes olivaceus and Olive-striped Flycatcher for Mionectes galbinus if we decide to split
these two groups. These are the names used by del Hoyo and Collar 2016, and
used for the groups corresponding to the species recognized by del Hoyo and
Collar in the Birds of the World account (Fitzpatrick et al. 2020).
References:
Boesman, P. F. D. 2016.
Notes on the vocalizations of Olive-striped Flycatcher (Mionectes olivaceus). Birds of the World
Ornithological Note 117. In: Birds
of the World. Cornell Lab of Ornithology,
Ithaca, NY. (retrieved from birdsoftheworld.org/bow/ornith-notes/JN100117
on 25 March 2022.).
del
Hoyo, J., and N. J. Collar. 2016. HBW and BirdLife International Illustrated
Checklist of the Birds of the World. Volume 2. Passerines. Lynx Edicions,
Barcelona, Spain.
Fitzpatrick, J. W., J. del Hoyo, N. Collar, E. de Juana, G. M. Kirwan,
and A. J. Spencer. 2020. Olive-striped Flycatcher (Mionectes
olivaceus), version 2.0. In Birds of the World (T. S.
Schulenberg and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY,
USA. https://doi.org/10.2173/bow.olsfly1.02
Harvey, M. G., G. A.
Bravo, S. Claramunt, A. M. Cuervo, G. E. Derryberry, J. Battilana, G. F.
Seeholzer, J. S. McKay, B. C. O’Meara, B. C. Faircloth, S. V. Edwards, J.
Pérez-Emán, R. G. Moyle, F. H. Sheldon, A. Aleixo, B. T. Smith, R. T. Chesser,
L. F. Silveira, J. Cracraft, R. T. Brumfield, and E. P. Derryberry. 2020. The
evolution of a tropical biodiversity hotspot. Science 370:1343-1348.
Tobias, J.A., N. Seddon,
C. N. Spottiswoode, J. D. Pilgrim, L. D. C. Fishpool, & N. J. Collar 2010.
Quantitative criteria for species delimitation. Ibis 142:724-746.
Doug Stotz, February 2023
Note
from Remsen on English names: if this passes, a separate proposal would be
needed; see discussion of possibilities above.
Comments from Remsen (as in my NACC
comments):
“NO. Tough call for me. As noted in the proposal, M. olivaceus
is a paraphyletic taxon certainly consisting of multiple species, and Boesman’s
preliminary analysis indicates vocal differences consistent with species rank
for several populations. But this is a
case in which a piecemeal approach seems unwise, especially in the case of galbinus-hederaceus,
because we don’t have genetic data from what would be the taxon in the NACC
area (hederaceus) (Harvey et al. included only 3 subspecies of M.
olivaceus) and because according to the proposal, galbinus and hederaceus
are the most divergent taxa in terms of plumage. Boesman and Harvey et al. have set the stage
for a future, thorough analysis that will allow us to sort all this out in
terms of taxonomy.
“One could make the argument that it is more
important to split olivaceus into two species to remove the problem of
maintaining a paraphyletic species than it is to wait to sort out all the
details, which affect mainly extralimital taxa (South America) anyway. I understand that rationale, and I am
convinced from the published sonograms and measurements of the vocal parameters
in Boesman (2016) that the NACC area has two species-level taxa (nominate olivaceus
vs. hederaceus). I am not opposed to piecemeal taxonomic change, would
support it if we were reverting to a prior treatment rather than a novel one,
and would support that split if the data behind it were solid. But are they solid? The genetic data for paraphyly are based on
Harvey et al. 2020, excerpted below:
“Note that
only 5 individuals were sampled: 2 M. striaticollis and 3 M.
olivaceus. The proposal notes that
the 3 olivaceus samples represent 1 sample each of nominate olivaceus,
galbinus, and venezuelensis (the latter two the sisters in the
tree). That only leaves out Boesman’s
Santander vocal group* (which evidently cannot be assigned to subspecies
yet). But it also leaves out two
critical subspecies, including the one from the NACC area: hederaceus. Splitting everything from nominate olivaceus
as one species assumes that hederaceus and fasciaticollis group
with galbinus and venezuelensis rather than olivaceus. That is the most likely outcome based on
biogeography, but it is not a certainty.
Hederaceus is the closest taxon (parapatric evidently) to
nominate olivaceus. We are
assuming hederaceus groups with galbinus because of Boesman’s
vocal analysis (more on that later), but the proposal noted that they are at
opposite extremes of plumage variation in the complex, so that is a
concern. Even fasciaticollis, the
most distant taxon from nominate olivaceus, occurs as close as southern
Colombia, and cannot be dismissed completely as a potential disjunct, sister
taxon to nominate olivaceus.
“And then there is
another potential problem: there are two additional unsampled named taxa that
were subsumed into venezuelensis on the say-so of Fitzpatrick in HBW
without any real analysis: pallidus Chapman, 1914 (TL = Buena Vista,
4500 ft., above Villaviscensio, Meta, Colombia), and meridae Zimmer,
1941 (type loc = near Mérida, Venezuela).
Mel Traylor, in his Tyrannidae chapter in “Peters” 1979 recognized both
subspecies. Traylor gave the range of pallidus
as “Upper tropical and lower subtropical zones of Eastern Andes of Magdalena
and northern Meta, Colombia” and of meridae as “Subtropical zone of
northwestern Venezuela from western Zulia and Falcon to Táchira, and Norte de
Santander and Boyacá in adjacent northeastern Colombia.” Note that according to the proposal Norte de
Santander is region from which Boesman described a separate vocal group, and so
I strongly suspect Fitzpatrick unjustly sunk meridae; here’s what
Fitzpatrick said: “pallidus …. and meridae … are indistinct,
intermediate forms within a cline, both treated as synonyms of venezuelensis.” That’s it.
It should be noted that Fitzpatrick synonymized a number of tyrannid
subspecies based on statements like this, and that some of these synonymized
taxa are actually vocally distinct (e.g. Phyllomyias griseiceps, which
he treated as monotypic).
“As far as Boesman’s
vocal data go, his N for nominate olivaceus was 6 and for hederaceus,
19. So that looks solid, and just
eyeballing the sonograms suggests to me that these are the most different of
the vocal groups. Then, for galbinus
from the Santa Martas, N=1. On the basis
of that one recording, Boesman groups galbinus with our hederaceus. Again
eyeballing the sonograms, that single recording does bounce around like hederaceus,
but to my eye, the note shapes (lopsided “U”) of galbinus look more like
Andean venezuelensis and fasciaticollis than they do those of hederaceus
….Which actually makes more sense biogeographically in terms of
relationships. Boesman does not have a
specific metric for note shape, by the way.
“So, in summary, we
would be making a novel taxonomic change based on 5 individual genetic samples
that do not include the critical taxon hederaceus, which happens to be
the one of the largely South American group represented in the NACC area. Yet we would be assigning the species name galbinus
to that species, and hederaceus would be a subspecies of galbinus. And that taxonomy would be based on Boesman’s
analysis of a single recording, the sonogram of which to my eye looks more like
the Andean taxa, not hederaceus.
Further, our case for paraphyly is actually weak with respect to the two
taxa in our area because we don’t have a genetic analysis that included hederaceus. Am I the only one queasy about all this? Yes,
we’ve got two species in the NACC area, and we can punt the other problems to
SACC, but it just seems awfully sloppy and laden with compound
assumptions. Imagine the egg-on-face
fallout if there is something wrong with our current understanding once we have
genetic and vocal data from all 5 (or 7) taxa?
I don’t see why we should take that risk.
“* my
downloaded version of Boesman (2016) states that this vocal group is from
Caripe, Venezuela, and thus pertains to venezuelensis, so I’m not sure
what’s going on here except that Doug must have access to a more recent
revision.”
Comments from Areta: “Harvey et al. (2020) show that olivaceus is deeply
paraphyletic (Panama sample would be olivaceus,
Colombian samples would be galbinus
from Santa Marta and hederaceus
from Tamá):
“The
problem I see is that by splitting the nominate olivaceus from the rest, we would have a new
use for the name galbinus
to be applied to what seems to be at least 2-3 species, thereby leading to a
new faulty taxonomy.
“The
variation in vocalizations of these Mionectes
requires more thorough quantification. In a rapid examination in XC and in the
NACC proposal, the differences in sounds do not match the species limits
outlined by BirdLife, and because so much variation remains unexplained, I
don´t think a good case has been made to adopt this split, even when it seems
quite clear that there are multiple species within M. olivaceus
as currently circumscribed.
“I
am seriously concerned by these “express” splits. I have no doubt that olivaceus is a different
species, but as a taxonomic committee, I think that we should be worried about
deeper issues, such as the new application of the name galbinus (a Santa Marta
endemic?) at the species level for another array of species. Then this rather
unsatisfactory usage will spread, only to be changed sooner than later. As
such, I prefer to stick to known historical errors of wide application instead
of incurring in a new kind of error affecting more taxa (e.g., venezuelanus would in all
probability have now been erroneously considered to pertain to olivaceus AND galbinus). To me, we do a
disservice to stability by accepting splits such as this one, and this is why
to me not all the "clear splits" are equally acceptable. We have to
deal with species-level entities and their names, and this is where things get
muddy. In this case, I don´t think that the piecemeal approach to taxonomy is
adequate. This complex needs to be sorted in one movement, lest we create a
large number of ephemeral taxonomies and ensuing confusion.”
Comments from Lane:
“NO, largely for the reasoning Van puts forth. Whereas I suspect
splits will be necessary once we gain a better understanding of the various
taxa involved (both molecularly and vocally), the taxonomy makes me leery of
splitting using the wrong daughter names (much as was almost the case with
Herpsilochmus rufimarginatus and
frater). As it happens, I literally made a recording yesterday in the
Santa Martas-- as “bycatch” in the background of
another recording (and thus ID not visually confirmed)--that has the same
vocalization that Niels identified as M. o.
galbinus (XC235896). My recording
uploaded here: https://macaulaylibrary.org/asset/534205891.
“I note that XC235896 has in its notes that the singer was *not
seen* and so I don’t know what grounds Niels used to identify that voice as
M. o. galbinus! However, I used Niels' recording to play back
to a bird I was watching later yesterday, and it seemed
briefly to respond
positively, approaching me once before returning to foraging (and not showing
interest again despite more playback). Given the lack of representation of key
taxa in a phylogeny, the lack of confirmation of ID of several key recordings
(such as the XC recording above), and the reluctance to have to backtrack on
species names if the results of those future studies contradict what has been
proposed, I would rather stay at status quo until things are clearer.”
Comments from Robbins: “NO. Clearly, multiple species
are involved, but as Van and Dan point out we need additional information on a number
of facets of this complex before any splits are made.”
Comments from Stiles: “NO for splits at this time; the plumages
of all are very difficult to tell apart, and unfortunately, my post-malarial
ear is deaf to the songs, so I’d like to see a more thorough genetic analysis
with birds also recorded and if possible, a colorimetric analysis to get this
one sorted out.”
Comments
from Del-Rio (who has Pacheco vote): “NO. I would like to see a more
complete study of this complex, including sound recordings and molecular data.”
Comments from Zimmer: “NO. The molecular
data are pretty clear that M. olivaceus, as currently constituted, is
paraphyletic. But Boesman’s vocal
presentation, while a good start, leaves the question of how many splits should
be recognized as the taxonomic equivalent of a “jump ball”. I would want to see a more broadly sampled,
detailed, quantitative vocal analysis, not just a handful of spectrograms, no
matter how much those tracings would appear to differ.”
Comments from Claramunt: “NO. Vocal
and genetic data really suggest that the taxon in Costa Rica and W Panama is a
different species, but I agree with others in that more evidence is needed, in
particular, data about birds in central and eastern Panama.”