Proposal (748) to South American Classification Committee
Recognize Sicalis holmbergi as a new species
A putative new species, Sicalis holmbergi, is described by López-Lanús (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 típico" 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 López-Lanús 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.
Areta, J.I. 2008. Entre Ríos 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 Ornithologists’ Club 131: 4-23
Areta, J.I., Pearman, M. & R. Ábalos. 2012. Taxonomy and biogeography of the Monte Yellow-Finch (Sicalis mendozae): understanding the endemic avifauna of Argentina’s 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
López-Lanús, B. 2017. Una nueva especie de jilguero (Thraupidae: Sicalis) endémica de las Sierras de Ventania, pampa bonaerense, Argentina. In pp. 475-497: López-Lanús, B. Guía Audiornis de las aves de Argentina, fotos y sonidos; identificación por características contrapuestas y marcas sobre imágenes. Segunda edición. 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 45:277–285
Nacho Areta and Mark Pearman, April 2017
Comments from Jaramillo: “NO. 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 “hooded” Phrygilus at some point, including all of these isolates and oddballs that there are in these groups, as well as to assess hybridization within Phrygilus.”