Proposal (893) to South American Classification Committee
Merge Stymphalornis into Formicivora
Background: In 1995 Marcos Bornschein, the late Bianca Reinert, and Dante Martins Teixeira described a new species of antbird from southern Brazil (Bornschein et al. 1995). At the time of discovery, this species was represented by only two specimens, an adult female and an immature male. Bornschein et al. noted a resemblance, both in general shape (long slender bill, long graduated tail) and plumage between the new species and some species of Formicivora. On the basis of an apparently distinctive pattern of syringeal musculature, however, Bornschein et al. erected a new genus, Stymphalornis, for the new species, acutirostris.
New information: Shortly thereafter, Luis Gonzaga completed a phylogenetic analysis of Formicivora based on external morphology, syringeal morphology, vocalizations, and natural history characters (Gonzaga 2001). Gonzaga made it a point to include Stymphalornis in this survey. He concluded that Stymphalornis was embedded in Formicivora, and was most closely related to White-fringed Antwren Formicivora grisea and Rusty-backed Antwren Formicivora rufa. As a result, when a second taxon (paludicola), closely related to acutirostris, was described in 2013, it was described in Formicivora (Buzzetti et al. 2013). (Note that the co-authors of Buzzetti et al. included both Reinert and Bornschein, two of the three describers of Stymphalornis.)
Soon thereafter, Gustavo Bravo published a phylogenetic analysis of antwrens based on DNA sequence data, from both mitochondrial and nuclear genes (Bravo et al. 2014). Bravo et al. confirmed both that Stymphalornis is embedded in Formicivora and that it is most closely related to Formicivora grisea and Formicivora rufa.
Analysis: Multiple lines of evidence consistently indicate that Stymphalornis is best treated as a junior synonym of Formicivora. SACC has been aware of this issue at least since the time it deliberated on whether to recognize paludicola as a species (comments in AOS-SACC Proposal 693, Recognize Formicivora paludicola as a valid species), but has not elected to address the question. In the meantime, other checklists have stayed current with recent advances with respect to avian taxonomy, and classify acutirostris and paludicola in Formicivora (Dickinson and Christidis 2014, Piacentini et al. 2015, del Hoyo and Collar 2016).
Recommendation: I recommend that SACC transfer Stymphalornis acutirostris (including paludicola) to Formicivora.
Bornschein, M. R., B. L. Reinert, and D. M. Teixeira (1995) Um novo Formicariidae do sul do Brasil (Aves, Passeriformes). Publicação Técnico-Científica do Instituto Iguaçu de Pesquisa e Preservação Ambiental 1: 1-18, Rio de Janeiro.
Bravo, G. A., J. V. Remsen Jr., and R. T. Brumfield (2014) Adaptive processes drive ecomorphological convergent evolution in antwrens (Thamnophilidae). Evolution 68: 2757–2774. https://doi.org/10.1111/evo.12506
Buzzetti, D. R. C., R. Belmonte-Lopes, B. L. Reinert, L. F. Silveira, and M. R. Bornschein (2013) A new species of Formicivora Swainson, 1824 (Thamnophilidae) from the state of São Paulo, Brazil. Revista Brasileira de Ornitologia 21: 269–291. http://www.revbrasilornitol.com.br/BJO/article/view/5409
Dickinson, E.C., and L. Christidis (2014) The Howard & Moore complete checklist of the birds of the world. Fourth edition. Volume 2. Aves Press, Eastbourne, United Kingdom.
Gonzaga, L. P. (2001) Análise filogenética do gênero Formicivora Swainson, 1825 (Aves: Passeriformes: Thamnophilidae) baseada em caracteres morfológicos e vocais. PhD dissertation, Universidade Federal do Rio de Janeiro, Rio de Janeiro. https://pantheon.ufrj.br/bitstream/11422/3518/70/542849.pdf
del Hoyo, J., and N.J. Collar. 2016. HBW and BirdLife International illustrated checklist of the birds of the world. Volume 2. Lynx Edicions, Barcelona.
Piacentini, V. de Q., A. Aleixo, C. E. Agne, G. N. Maurício, J. F. Pacheco, G. A. Bravo, G. R. R. Brito, L. N. Naka, F. Olmos, S. Posso, L. F. Silveira, G. S. Betini, E. Carrano, I. Franz, A. C. Lees, L. M. Lima, D. Pioli, F. Schunck, F. Raposo do Amaral, G. A. Bencke, M. Cohn-Haft, L. F. A. Figueredo, F. C. Straube, and E. Cesari (2015) Annotated checklist of the birds of Brazil by the Brazilian Ornithological Records Committee / Lista comentada das aves do Brasil pelo Comitê Brasileiro de Registros Ornitológicos. Revista Brasileira de Ornitologia: 90–298. http://revbrasilornitol.com.br/BJO/article/view/1263/pdf_905
Tom Schulenberg, December 2020
Comments from Remsen: “YES. The genetic data require this merger.”
Comments from Stiles: “YES. Transferring this species to Formicivora is long overdue, given the solid genetic evidence.”
Comments from Areta: “YES. A long overdue change! I confess that I adore the name Stymphalornis, but it has to make place to Formicivora for all the known reasons.”
Comments from Jaramillo: “YES. No comments other than I am saddened to lose Stymphalornis.”
Comments from Zimmer: “YES. Multiple data sets (genetic, vocal, morphological, ecological) strongly support this change.”
Comments from Robbins: “YES, the Bravo et al. molecular data set make this a straightforward decision of merging Stymphalornis into Formicivora.”
Comments from Bonaccorso: “YES. All available evidence supports this change.”
Comments from Pacheco: “YES. Approving a widely accepted decision.”