Proposal (#299) to South American Classification Committee
Split Hypocnemis cantator by elevating H. flavescens, peruviana, subflava, ochrogyna and striata to species rank
Background: Isler et al. (2007) proposed that "six populations of Warbling Antbird (Hypocnemis cantator) currently considered subspecies are more appropriately recognized as species" based mainly on their comparative analyses of vocal differences, but also on plumage coloration. Furthermore, "two forms currently considered subspecies are syntopic and two others are parapatric without apparent physical barriers." The authors recommend treating the H. cantator complex as the following six species, and hyphenate the English name Warbling-Antbird after modifying it:
Hypocnemis cantator Guianan Warbling-Antbird
Hypocnemis flavescens Imeri Warbling-Antbird
Hypocnemis peruviana Peruvian Warbling-Antbird
Hypocnemis subflava Yellow-breasted Warbling-Antbird
Hypocnemis ochrogyna Rondonia Warbling-Antbird
Hypocnemis striata Spix's Warbling-Antbird
Effect on South American CL: Splitting Hypocnemis cantator Warbling Antbird into six species adds five species to the list, and requires modifying the English name for Hypocnemis cantator.
Recommendation: Isler et al. (2007) state that further molecular phylogeny work on the H. cantator complex is forthcoming, which could provide new evidence that additional subspecies should be elevated to species status, or that other subspecies are not valid taxa. Regardless, the authors advocate "this initial revision better reflects the taxonomic status of populations in the complex than current classifications." I recommend voting "Yes".
Isler, M. L., P. R. Isler, & B. M. Whitney. 2007. Species limits in Antbirds (Thamnophilidae): The Warbling Antbird (Hypocnemis cantator) complex. Auk 124(1):11-28.
Daniel Lebbin, August 2007
Comments from Remsen: "YES. Having been aware of this one for a while and having gone over the analyses, these taxa merit species rank under the BSC using the careful comparative framework established by the Islers and Whitney. The case of local syntopy of elevates automatically at least two of the taxa to species rank.
"As an aside, however, I note that additional genetic data will not add anything to to our understanding of species limits of allopatric populations (because degree of genetic divergence in 1-2 genes cannot be used as a measure of taxon rank), but rather only the cases of parapatry as noted, where presence or lack of gene flow becomes relevant. As for genetic data contributing to recognition of populations as subspecies, that would apply if and only if the genes governing the phenotypic differences that distinguish them could be discovered and sequenced; otherwise, validity of subspecies depends on their phenotypic diagnosability, and contrary to several published statements, any lack of differentiation in a couple of genes (out of ca. 25,000) is essentially irrelevant to ranking those populations as subspecies (= phenotypically diagnosable units)."
Comments from Stiles: "YES. The analyses look solid, there is sufficient evidence under the BSC to justify these splits, and they are diagnosable morphologically as well. And as Van stated, genetic distances (at the degree of detail where we are now working) in themselves do not supply appropriate criteria for making taxonomic decisions in the species-subspecies range."
Comments from Jaramillo: "YES - I am not wild about the hyphenated names, however, but it could be worse."
Note from Thomas Donegan: "A note on English names only: I understand that English names for this group have been discussed before at some length by SACC. However, I would like to note (not as a formal proposal) that the novel name 'Antwarbler' would be perfect for this group (Guianan Antwarbler, Imeri Antwarbler, etc.). One is effectively starting from scratch with the species formerly known as Hypocnemis cantator so stability arguments can go out of the window; hyphenated names here are a bit of a mouthful; and there are lots of birds in this family and related ones whose names are constructed by the word "Ant" plus the name of an old world bird group. 'Warbler' has not yet been used for Thamnophilids etc. but would be rather apt here. Rather than "Warbling-Antbirds", why not cut out the clutter and make them all "Antwarblers"?"
Comments from Robbins: "YES. The combination of sympatry in two of the taxa, coupled with vocal differences among the others supports species recognition for all."
Comments from Nores: "NO. Pienso que la evidencia aportada por Isler et al. es importante pero no definitiva como para crear 5 nuevas especies. Es más, ellos mismos mencionan " Further recomendations regarding status of all taxa within the Warbling Antbird complex and estimates of its phylogeny within the Thamnophillidae await molecular analysis now underway" and "awaiting the completion of further molecular, morfhological and behavioral studies". A pesar de lo que menciona Remsen sobre los datos moleculares, yo esperaría esos resultados u otro tipo de análisis antes de crear las especies. Por el momento, yo sólo pasaría a especie a subflava por estar en simpatría con peruviana. La parapatría de cantator y flavescens señalada por Isler et al. y usada por Lebbin en su propuesta para apoyar la creación de las especies, para mi sugiere más subespecies que especies. Yo he tenido oportunidad de observar a esta especie en diferentes partes de Amazonia y nunca noté diferencias importantes (con un análisis mucho menos profundo que el de Isler et al.) ni en la coloración ni en el canto como para pensar en diferentes especies."
Comments from Cadena: "YES. The analyses look solid and the documented sympatry of two of the taxa with no evidence of hybridization really clinches the argument. I agree that molecular data would have little to offer here other than giving estimates of divergence times, which may or may not say anything about species status. Perhaps the only situation where DNA data would be of great value would be those of parapatric populations. Manuel's conservative suggestion of elevating only peruviana an subflava to species status might be sensible, but it would leave the question open of how do you treat the rest of the taxa: subspecies of peruviana? of subflava? of cantator? How would one decide?"
Comments from Pacheco: "YES. Os resultados da análise dos Islers e Whitney são, ao meu ver, suficientes para o tratamento de 6 espécies no complexo Hypocnemis cantator em qualquer dos conceitos de espécie em uso."
Comments from Zimmer: "YES. The data are solid on this. Vocal differences between sympatric populations of peruviana and subflava/collinsi provide an excellent yardstick for assessing the importance of vocal differences between other populations in the complex, most of which differ in more vocal characters than do peruviana and subflava/collinsi."