Proposal (548) to South American Classification Committee
Recognize
newly described Cinclodes espinhacensis
Effect on South American CL: This proposal would add a newly described species to the list.
Background: Freitas et al. (2012)
discovered a new population of Cinclodes,
most closely related to C. pabsti, in
Minas Gerais, Brazil, where it inhabits campo
rupestre habitat in the Serra do Cipó area in the southern portion
Espinhaço Range, over 1100 km N of the range of C. pabsti. It is thus
by far the most isolated population of any Cinclodes.
Freitas
et al. compared their 10 specimens of the new population to 6 of C. pabsti. Their published photos and description make it clear that
this new population differs in being much darker overall and is thus represents
a diagnosable unit worthy of taxonomic recognition.
The authors designated their new
taxon as a species under BSC criteria because songs were diagnosably different
in terms of frequency and duration.
They analyzed 26 recordings of songs of 4 individual espinhacensis and 30 of 4 individual pabsti, and found statistically
significant differences in 8 of 17 parameters. They also analyzed 475 recorded call notes of 12 individual espinhacensis and 225 of 8 individual pabsti, and found statistically
significant differences in 3 of 6 parameters measured. (I am concerned, however, about
independence – using multiple recordings of the same individuals as
independent units of analysis is questionable.) The sonograms show the longer duration of the call notes and
the lower frequency of the song.
The authors also analyzed mtDNA
sequence data (2528 bp, 4 loci) for 11 espinhacensis
and found that it is reciprocally monophyletic with respect to its sister
taxon, pabsti. Genetic distance between the two is
small, although slightly greater than that between C. taczanowskii and C.
nigrofumosus and only slightly less than that between C. oustaleti and C. olrogi.
Analysis and Discussion: This one is right on the
border of the subspecies/species boundary, and the authors have done almost everything
they could to produce data relevant to the basic question under the BSC for
allopatric taxa, namely, has this new form diverged to the degree associated
with known species limits in related birds? The only missing piece is playback trials.
I
lean towards treating espinhacensis
at the species rank because there are more data to support ranking it as a
separate species than there are for treating C. taczanowskii as a separate species from C. nigrofumosus, or C.
aricomae from C. excelsior. Further, we know from Sanín et al. (2009)
that morphological differentiation among good species in the C. fuscus is minimal. Overall, species differences are slight
among species in the various species groups in Cinclodes.
Recommendation:
I recommend a "yes" vote to add this newly described species to the
South American list.
References:
FREITAS,
G. H. S., A. V. CHAVES, L. M. COSTA, F. R. SANTOS, AND M. RODRIGUES. 2012. A new species of Cinclodes from
the Espinhaço
Range, southeastern Brazil: insights into the biogeographical
history of the South American highlands. Ibis
154: 738-755.
SANÍN,
C., C. D. CADENA, J. M. MALEY, D. A. LIJTMAER, P. L. TUBARO P.L., AND R. T.
CHESSER. 2009. Paraphyly of Cinclodes fuscus (Aves: Passeriformes: Furnariidae): Implications
for taxonomy and biogeography. Molecular Phylogenetics and Evolution 53:
547-555.
Van Remsen,
September 2012
Comments from Zimmer: “YES.
I agree with Van that this one seems
borderline in terms of being divergent enough from pabsti to be recognized as a species rather than a subspecies. Then again, as Van also points out,
plumage (and voice) is evolutionarily conservative in this group. The Espinhaço Range is a mini-center of
endemism (e.g. Asthenes luizae, Augastes scutatus), and the range
disjunction from pabsti is large, so
treating the two as separate species makes sense biogeographically, and, they
would appear to be safely on independent evolutionary trajectories.”
Comments from Stiles:
“YES, for reasons summarized by Kevin and
Van.”
Comments from Nacho Areta and Mark Pearman: “The description of a new species of Cinclodes by Freitas et al. (2012) is an interesting case. We believe that the authors of the paper describing Cinclodes espinhacensis have missed the opportunity of making a more useful comparison of vocalizations in the genus and have based their conclusion mostly on our previous lack of knowledge to justify their species instead of putting forward a better frame to understand what a species should be in Cinclodes. There is no thorough comparative study of other species vocalizations or morphology and no evaluation of behavioral responses to playback, and thus no possibility of evaluating whether the differences described should be interpreted as indicating the existence of a new species or of a new subspecies. Weighing up the evidence mentally in comparison to Cinclodes with which we are familiar (including pabsti), does not reveal any meaningful biological difference between espinhacensis and pabsti to justify their treatment as different species. More objective reasons to support this view are summarized below.
“Vocalizations: even though Freitas et al. (2012) have found differences in some acoustic parameters, these are highly variable, and there is no mention on whether the cuts were unsolicited or in response to playback, which may influence parameters such as pitch and number of notes per vocalization (let alone differences due to different recording gear and recording quality), several acoustic parameters also show no difference (9 out of 17 parameters show no difference, while 8 out of 17 do; how should we interpret this?), the shape of notes in the songs is identical (the call is also extremely similar in every respect with 3 out of 6 parameters showing no differences; without a clear ‘yardstick’ we cannot evaluate just how conservative songs are in Cinclodes), and finally there is a whole lot of pseudoreplication in their measurements as it is not clear how many calls and songs from each individual they've measured (i.e., individual consistency and species level differences are conflated).
“
Morphology: there is no diagnosable morphometric difference except for tarsus (with a large p, though...) and weight (which is awkward, given that morphometrics usually correlated with weight such as wing size are identical; we are in the presence of two birds with very similar shapes which have dramatic weight differences, perhaps an artifact of weighing birds in different seasons and/or with different tools?)
“Comparison to Upucerthia: given the lack of comparative data within Cinclodes, looking at its sister genus Upucerthia is warranted. The authors didn't mention the existence of ecogeographic variation in Upucerthia (e.g., U. dumetaria and U. jelskii), which may easily explain the difference in coloration between espinhacensis/pabsti without necessarily meaning that a different species is involved (indeed, all undisputedly valid species in Cinclodes [and Upucerthia] differ in pattern and coloration, not just coloration). Tail pattern is particularly important in Cinclodes yet pabsti and espinhacensis show identical tail patterns. The level of differentiation found between espinhacensis and pabsti seems equivalent to that between Upucerthia jelskii and U. validirostris two ‘species’ that answer readily to playback of each other (whose vocalizations are so variable that they defy any meaningful quantitative characterization despite being structurally undistinguishable as is the case of note shape [and pattern?] in espinhacensis/pabsti) and which should be considered as part of a single geographically variable species (Areta and Pearman in press). If the darker saturation of dorsal plumage in espinhacensis is the only difference between it and pabsti, then similar distinctions at subspecies rank or indeed at color morph level can be found in numerous furnariid species (Remsen 2003).
“Genetic differences: the meager genetic differentiation, with values falling between those of the conflictive cases oustaleti-olrogi and nigrofumosus-taczanowskii, adds little to answer the question of the species-level of espinhacensis but if anything, it should raise suspicion.
“Geographical gap: finally, we would like to stress that the gap between espinhacensis and pabsti should not be used as a tool for species-level assignment. A large gap (for the poor flying Scytalopus) of 450 km is known to exist (or was known to exist) between records of S. iraiensis in Paraná and Minas Gerais, which may well be a sampling artifact (Vasconcelos et al. 2008). How much of the gap between espinhacensis and pabsti is an artifact? Let us also consider that species such as Cinclodes fuscus may easily fly 3000 km from Patagonia to Buenos Aires and another 3000 km back every season during their migration (and perhaps much more, when reaching south-east Brazil). To be clear: the gap between espinhacensis and pabsti is within flight distance of at least one migrant Cinclodes, and all inland Cinclodes have powerful flights.
“In sum, we do not see evidence for considering the Espinhaço birds as a different (biological) species from southern birds, and hope these arguments will generate an interesting discussion for SACC members.
“References
Areta, J.I. and M. Pearman. In press. Species limits and clinal variation in a widespread high Andean Furnariid: the Buff-breasted Earthcreeper (Upucerthia validirostris). Condor.
Remsen, J.V. Jr. 2003. Family Furnariidae (Ovenbirds). Pp. 162-357 in: del Hoyo, J., Elliot, A. & Christie, D.A. eds. (2003) Handbook of the Birds of the World. Vol. 8. Broadbills to Tapaculos. Lynx Editions, Barcelona.
Vasconcelos, M. F., Maurício, G. N., Silveira, L. F. and G. M. Kirwan. 2008. Range extension for Marsh Tapaculo Scytalopus iraiensis to the highlands of Minas Gerais, Brazil, with an overview of the species’ distribution. Bull. B. O. C. 128:101-106.”
Comments from Thomas Donegan: “This is a comment on some of the analysis of data on continuous
variables (biometrics and voice) in this paper, following up on Nacho Areta's
comments. The authors include means, standard deviation, and range
data for all the variables measured. They cite various variables as differing
in the "diagnosis" section, making it clear which variables overlap
and which do not. If one looks at table 2 (page 7), there are no
vocal variables that are diagnosable based on recorded values (range data
overlapping) - even if t and p shows they are statistically mildly
differentiated. No attempt in the paper is made to use statistical tests for
diagnosability. Following the nomenclature for stats in my recent series
of papers, the authors of this new taxon therefore looked only at
"Level 1" (statistical significance of differences between means
using t; the weakest form of differentiation) and "Level 4"
(diagnosability based on recorded values; which is the form of differentiation
most subject to biases related to sample size). The Isler et al. 97.5%
test of diagnosability was not applied, nor were any tests of 50% or 75% diagnosability.
Out of the continuous vocal and biometric variables studied, only body mass
appears to have met the "Level 4" test. However, here, the
means are less than four average standard deviations apart, so would not meet
statistical tests of diagnosability (Level 5), even before controlling for
sample size. I do not know these birds and do not want these comments to
detract in any way from appreciation of the authors' efforts in discovering and
publishing many interesting details of this previously undescribed new taxon.
Other data, notably molecular and plumage data, will be relevant to the
question of species rank too."
Additional comments
from Zimmer: “One of the
highlights of the tour was our couple of days in the Espinhaço range, where we
were able to locate a couple of pairs of the recently described Cinclodes
espinhacensis. I had voted on the relevant proposal (#548) to the
SACC just prior to the trip, rendering my vote based solely on available
information as presented in Freitas et al. (2012), and upon extensive field
experience with the closely related Cinclodes pabsti. With the
additional benefit of field experience with the newly described taxon, I would
like to add some additional perspective to my earlier comments.
“I found the morphological distinctions of espinhacensis relative
to pabsti to be just as described by Freitas et al. (2012),
i.e. espinhacensis is markedly darker dorsally, with a
slightly, but noticeably more clouded breast (lending a slightly
"bibbed" appearance), and appears more slender and less bulky in
build. Collectively, I still feel that these morphological distinctions
meet the yardstick test of other species-pairs of Cinclodes in what
is clearly a group in which morphology has proven evolutionarily conservative.
“My field experience did however provide revelations concerning the
vocalizations of espinhacensis relative to those of pabsti.
We already knew from Freitas et al. (2012) that the two taxa had broadly
similar loudsongs and single-note calls. I had the opportunity to
evaluate the vocalizations (both songs and calls) from 2 pairs of espinhacensis,
and to perform unidirectional tape playback experiments by presenting both
pairs of espinhacensis with playback of songs and calls of pabsti.
When we encountered the first pair of espinhacensis, they were
foraging on the ground ca. 100 m away from us. I barely initiated
playback of songs (no calls) of pabsti, before the pair of espinhacensis came
rocketing in toward us like heat-seeking missiles. They perched on the
nearest fence posts and sang back repeatedly and without letup, all the while,
vigorously flapping their wings in a display nearly identical to what I have
seen pairs of pabsti do on numerous occasions. I might add
that the wind was blowing in the range of 20-30 mph at the time, and passerines
in general were not exposing themselves any more than they had to. The pair
of cinclodes had trouble staying on their perches, such was the strength of the
wind. On 3 occasions the birds flew off and perched more than 100 m away
from us, where they resumed singing in agitation. Each time I attempted playback of the song of pabsti (using
pre-recorded songs of 4 different individual pabsti from Rio Grande
do Sul), the pair of espinhacensis came roaring back in, singing
and displaying wildly.
“On our hike out of the area, we encountered another individual of espinhacensis
foraging along the margins of a large pond. This was clearly a different bird, located 500 m+ from the
first pair, which were still vocalizing in the distance behind us. This
time, we presented the bird with playback of the single-note calls (but no songs)
of pabsti (also recorded in Rio Grande do Sul). Once again, the reaction was immediate,
with the bird we were watching flying straight at us and landing on the ground
nearby and calling (single-note calls) over and over in apparent distress. Meanwhile, its presumed mate, which we
had not seen, flew in from the far side of the pond, circled us, and landed
nearby and gave several songs.
“So, we had 2 different pairs of espinhacensis respond
repeatedly and vigorously to playback of audio recordings of pabsti.
The first pair responded to loudsongs of 4 different individuals (These
were presented separately (ie. The birds came in the first time to playback of pabsti #1,
then flew off, then returned in response to pabsti #2 and so on.).
These recordings of pabsti varied noticeably in the length
and number of notes of the songs, and also in the pace and change of pace in
the songs. I've noticed this variation in songs of pabsti before,
and the variation between songs within a single individual is at least as great
as the variation between individuals, often reflecting differences in degrees
of agitation in response to playback. We witnessed the same phenomena
with the two pairs of espinhacensis, i.e. individual birds changed the
length and pace of their songs from one song to the next. We tape
recorded this as best as we could, although the persistent high winds were
hellish for recording. The second pair of espinhacensis reacted
equally strongly to pre-recorded single-note calls (in the absence of songs) of
pabsti. In all instances, the vocalizations of espinhacensis (both
songs and calls) were indistinguishable (to my ears at least) from those of pabsti.
“My personal opinion is that negative results from playback trials
are more significant than positive results. In other words, many taxa
that are universally recognized as being good biological species will still
respond positively to playback of other vocally similar species in the same
genus (for example, playback of almost any Thamnophilus antshrike
can be used to stimulate almost any other Thamnophilus species),
perhaps due to interspecific competition.
On the other hand, a complete absence of response to playback is usually
more informative, especially if the recipient of the playback responds to its
own voice without responding to the other taxon. And, I do think that the
voices of the various cinclodes are largely similar enough that a positive
response from one species to playback of another is not necessarily a
deal-breaker. However, in the current case, the response from 2 pairs of espinhacensis to
both single-note calls and loudsongs of pabsti was immediate,
dramatic, and vigorous, and accompanied by the same sorts of wing-flapping
displays that are used by other cinclodes in defending their territories
against conspecifics. I can think of plenty of closely related
species-pairs with parapatric/allopatric distributions in which the loudsongs
are nearly identical but the calls are very different (e.g. some pairs in the Hypocnemis
cantator complex), or, where the calls are nearly identical but the
loudsongs are very different (e.g. Schistocichla antbirds), but
seldom are both the calls and the songs as well as the associated territorial
displays identical.
“Also of note, is that my sense from reading Freitas et al. (2012)
was that espinhacensis differed further from pabsti in its
ecological associations, being restricted to higher elevations with a highly
endemic and specialized flora.
While that may be the case for the bulk of the population, the pairs of espinhacensis
that we encountered were at the lower elevational limit, and were frequenting
highly human-modified pasture and margins of seasonal ponds, all subject to
heavy grazing by cattle and horses -- in other words, the same kinds of
habitats where one finds pabsti in Rio Grande do Sul.
“In summation, the morphological distinctions of espinhacensis
do meet the yardstick test for species recognition (but could also be merely an
example of Gloger's Rule), but I do not believe the calls or the songs of these
birds are diagnosable from those of pabsti, and limited playback trials
suggest that these two populations, were they to come in contact, would still
treat one another as conspecific. There is no doubt in my mind that espinhacensis
is a valid taxon, and I do believe that they are on an independent evolutionary
trajectory from pabsti but at this point, I don't feel that they
meet our criteria for being recognized at the species level. Given the
advantage of hindsight, I would like to change my vote to NO, and recognize espinhacensis
as a distinct subspecies of Cinclodes pabsti.”
Cipo
Cinclodes (espinhacensis) by
Kevin Zimmer:
Cipo
Cinclodes (espinhacensis) by
Kevin Zimmer :
Long-tailed
Cinclodes (C. pabsti) by Kevin
Zimmer :
Additional comments from
Remsen: “In view of Kevin’s findings
and Nacho’s comments, I change my vote to NO. This is a valid new taxon but best ranked as a subspecies.”
Comments
from Robbins: “NO. Based on Kevin’s
field experience, especially the limited playback experiments, it seems best to
treat this new taxon as a subspecies.”