Proposal (748) to South
American Classification Committee
Recognize Sicalis holmbergi
as a new species
A putative new species, Sicalis
holmbergi, is described by L—pez-Lanœs (2017) on the basis of a single
specimen in fresh (winter) plumage and photographs of sound-recorded
individuals. As unconventional and complicated as the description of the Sporophila in SACC
Proposal 715, the same author chose to publish this
description in a privately published bird guide. There is no reference to an
entry in ZooBank of the species name, but the work might (or might not) qualify
as being validly published. We assess the description by its merits regardless
of whether it formally fulfills the requirements of the International Code of
Zoological Nomenclature.
The
morphological diagnosis is problematic and insufficient, and does not suffice
to justify full species or subspecies status. First, it does not provide any
character to diagnose the holotype of holmbergi
from other Sicalis in fresh plumage,
but notably fails to do so from auriventris.
At this point, it should be stated that this specimen was identified as S. auriventris in Areta et al. (2012),
who also mentioned a work in progress by Pearman and Chiappe in this regard.
Moreover, we do not see any difference in terms of plumage, shape, and size
between the male holotype and fresh-plumaged auriventris. Second, the type specimen is claimed to have a
slightly longer bill (exposed culmen 0.3 mm longer than the largest auriventris), a wider mandible (0.7 mm
wider than the largest auriventris),
and a longer tarsus (1.1 mm than the largest auriventris), but is indistinguishable in other measurements from auriventris. These tiny differences
might well be the result of measurement error or just indicate slightly larger
measurements in some variables of an otherwise normal individual of auriventris. Third, the author
acknowledges that birds in typical [worn] breeding plumage ("macho
reproductor de plumaje t’pico" also referred to as "amarillo
intenso") are indistinguishable from S.
auriventris. Fourth, the long primary projection that is so typical of S. auriventris is clearly visible in the
type specimen and in all pictures of live individuals in which wing shape can
be assessed, and the straight to very slightly curved culmen typical of S. auriventris is also evident in all
known pictures of the Sierra de la Ventana birds.
The
diagnosis based on vocalizations is unconvincing and does not suffice to
justify full species status. First, the spectrograms are of such poor quality
that one is left wondering where the similarities and differences lie in terms
of vocalizations. The statement that "The notes in the introduction of S. holmbergi are diagnostic due to their
simple structure, mainly composed of pointed inverted Vs" is erroneous as
can be seen in the spectrogram that we made using different acoustic parameters
(Figure 1). This spectrogram shows that each supposed note is made up by
complex notes in quick succession, so that there is not a simple structure and
that there are no inverted Vs. The aspect of introductory notes as
characterized by the author arises as the product of a poor choice of
spectrogram parameters that do not \ show the fine structure of the sound.
These vocalizations defy easy characterizations. Note that in the sample
showing the "notes" of S.
auriventris, their complex nature
is also evident. Second, the author
simply states that auriventris has a
conservative song pattern throughout its distribution, but the songs of auriventris are very complex (coming in
simple and complex versions, as in all Sicalis),
and vary geographically in some features. Despite this, auriventris seems to share the general song structure with holmbergi: in both cases a rather
monotonous series of metallic tinkling notes can be followed by a variable
number of series of different notes and sometimes a long chatter. Third, the
quantitative acoustic measurements lack any rigor and are presumably the
product of data taken from the visual inspection of spectrograms. For example,
the mention of a higher pitch in the vocalizations of holmbergi does not hold in a simple analysis: peak frequencies in
the random spectrograms here shown are astonishingly identical in one note of holmbergi and auriventris, and higher in a second note of auriventris (Figure 1). Finally, geographic variation in
vocalizations of Oscines deserves careful analysis, and does not automatically
imply species status for any such vocally different population. Indeed, work in
Sporophila has shown considerable
geographic variation in vocalizations without advocating species status for any
of those vocally distinctive and allopatric populations (Areta 2008, Areta et
al. 2011, Areta & Repenning 2011, Areta 2012).
Figure 1. Spectrograms showing
the complex structure of each "note" (delimited by horizontal lines)
in S. holmbergi and S. auriventris. Peak frequency
measurements for each note (in blue) and the spectrograms were made using the
same spectrogram parameters and the same sampling rate in both recordings.
Playback
experiments (n=6 experimental subjects) were conducted without rigor. It is not
clear whether each individual was subjected to multiple stimuli or not, and
there is no indication as to which playback stimuli were used; local stimuli
seem to have always been tried last, among many other shortcomings. Despite
this, the author interprets his results as indicating that individuals from
Sierra de la Ventana respond to vocalizations of this same population but
ignore those of S. auriventris, S.
uropygialis, S. olivascens and S. lebruni. Lack of methodological rigor
suggests that these results must be taken with skepticism.
The
presumed display flight of S. holmbergi
is so poorly described that it is not clear exactly what this display entails.
Singing in flight, which species such as S.
olivascens and S. auriventris do
undertake (contra L—pez-Lanœs 2017), is different from having a parachuting
display such as those of S. luteola
and S. citrina. The author provides
no data on where and, if indeed, when he studied auriventris in the field. Until more behavioral data are presented,
we are unable to confirm that this flight display in S. holmbergi is indeed diagnostic.
Finally,
the author does not mention the existence of populations of three other
Andean/Patagonian bird species in the Sierra de la Ventana: Catamenia analis, Asthenes modesta, and Agriornis
montanus. Although further study of these populations is warranted, the
examination of specimens by Pearman and Chiappe (unpublished MS) leaves no
doubt that these are all populations either directly assignable to the Andean
subspecies or at most subspecifically differentiated taxa. In this context, the
lack of diagnostic features of S.
holmbergi from the Andean/Patagonian S.
auriventris lends further support to our view that holmbergi is no more than an isolated population of auriventris.
This
description vividly illustrates the problems for bird taxonomy when a
manuscript is not published in a peer-reviewed journal. For the large number of
reasons stated above we recommend a NO
vote.
References cited
Areta,
J.I. 2008. Entre R’os Seedeater (Sporophila zelichi): a species that
never was. Journal of Field Ornithology 79: 352-363
Areta,
J.I. 2012. Winter songs reveal geographic origin of three migratory Seedeaters
(Sporophila spp.) in southern Neotropical grasslands. Wilson Bulletin 124:688-697
Areta, J.I., Noriega, J.I., Pagano, L. & I.
Roesler. 2011. Unraveling the ecological radiation of the capuchinos:
systematics of the Dark-throated Seedeater Sporophila ruficollis, and
description of a new black-collared form.
Bulletin of the British OrnithologistsÕ
Club 131: 4-23
Areta,
J.I., Pearman, M. & R. çbalos. 2012. Taxonomy and biogeography of the Monte
Yellow-Finch (Sicalis mendozae):
understanding the endemic avifauna of ArgentinaÕs Monte Desert. Condor 114: 654-671
Areta, J.I. & M. Repenning. 2011. Systematics
of the Tawny-bellied Seedeater (Sporophila hypoxantha). I. Geographic
variation, ecology and evolution of vocalizations. Condor 113: 664-677
L—pez-Lanœs, B. 2017. Una nueva
especie de jilguero (Thraupidae: Sicalis)
endŽmica de las Sierras de Ventania, pampa bonaerense, Argentina. In pp.
475-497: L—pez-Lanœs, B. Gu’a Audiornis de las aves de Argentina, fotos y
sonidos; identificaci—n por caracter’sticas contrapuestas y marcas sobre
im‡genes. Segunda edici—n. Audiornis Producciones. Buenos Aires, Argentina.
Schwartz,
P. 1975. Solved and unsolved problems in the Sporophila bouvronides/lineola
complex (Aves: Emberizidae). Annals of the Carnegie Museum 45:277Ð285
Nacho
Areta and Mark Pearman,
April 2017
___________________________________________________________
Comments from Jaramillo:
ÒNO. I have heard about the Sierra Ventana Sicalis for years, and after some
initial study decades ago by Pearman and others, I thought this had been
resolved as an isolate of S. auriventris.
So, it was surprising to see this description of a new species. I agree, there
is not enough here to conclude a new species is present, and both the analysis
and form of publication leave much to be desired. It would have helped to go
through rigorous peer review on this publication. Perhaps one could have
salvaged a good subspecies description somewhere in here. I am intrigued about
the playback situation, and think it would be wise to do some rigorous testing
along these lines, you never know? Also, it would be wonderful for someone to
perform a solid molecular analysis of Sicalis
and ÒhoodedÓ Phrygilus at some point,
including all these isolates and oddballs that there are in these groups, as
well as to assess hybridization within Phrygilus.Ó
Comments from Zimmer: ÒNO, for reasons painfully laid out in the Proposal. This one has disaster written all over
it!
Comments
from Stiles:
"NO. I agree that the description of this
ÒspeciesÓ lacks sufficient rigor and detail to merit acceptance. If holmbergi
is recognizable at all, it would best be considered a subspecies of cinereiventris."
Comments from Pacheco:
"NO. I follow the authors' recommendation of this proposal, based on the
inconsistency of the original work of description."
Comments from Robbins: "
NO, for many obvious reasons, as pointed out by Nacho and Mark."
Comments from Claramunt: "NO. The evidence is clearly
insufficient."
Comments from Cadena: ÒNO. I agree with the authors of the
proposal that the description leaves many open questions and fails to properly
demonstrate (1) that there is a diagnosable taxon in the area and (2) that if
such a taxon exists, it is sufficiently different from known taxa so as to be
considered a reproductively isolated species. Where this was published and the
argument about other species occurring in the area not differentiated from
populations in the Andes are not relevant to me in terms of evaluating the
evidence, although of course it would have been much better if the paper had
gone through the peer-review process at a journal.Ó