Proposal (585) to South American Classification Committee
Recognize newly described Herpsilochmus stotzi
Effect on South American CL: This proposal would add a recently described species to our main list.
Whitney, Cohn-Haft, Bravo, Schunck and Silveira (2013) recently described a new species of antwren, Herpsilochmus stotzi (Aripuana Antwren) from central Amazonian Brazil between the right bank of the Rio Madeira and the left bank of Rio Aripuanã, upriver to Rio Roosevelt, northwest Mato Grosso and adjacent northeastern of state of Rondônia. From this source, the main arguments to validate this species is summarized below:
Adult females of H. stotzi readily distinguished (“heterogyny” sensu Hellmayr 1929) from those of other taxa in the H. pileatus complex by paler, creamy-white throat contrasting more sharply with the orangish forecrown, and more extensively white posterior underparts; from a single adult female of H. praedictus (Predicted Antwren, west of the Rio Madeira described in the same special volume of HBW) by less densely orangish, more streaked or dappled, frontal region. Males of the H. stotzi appear to be indistinguishable from "white morph" and "intermediate" (Whitney et al. 2000) males of H. atricapillus.
Loud song of both sexes of H. stotzi immediately distinguished from those of similar H. atricapillus and H. pileatus by the lack of a distinct introductory series of notes, instead of starting with a relatively rapidly and evenly paced trill of essentially uniformly structured notes; and from much faster and more uniformly paced loudsong of Herpsilochmus praedictus by overall much slower pace and conspicuously decelerating finish. One common call is instantly distinguishable from presumably homologous calls of near relatives on note structure and auditory quality.
Finally, H. stotzi is separated from its sister-species Herpsilochmus praedictus west of the Rio Madeira by approximately 4% sequence divergence in the mitochondrial gene ND2.
In parallel with Ancient Antwren H. gentryi (Whitney & Alvarez 1998) of local distribution in upper Amazonia, H. stotzi occurs locally in campinarana, a lower-stature forest growing on nutrient-poor sandy soils.
Recommendation: I recommend a "YES" vote on accepting this antwren as a new species to our list, based on morphology, vocalizations, and genetic distinctions found among the related taxa.
HELLMAYR, C, E. (1929) On heterogynism in Formicarian birds. J. Orn. 77(Suppl.):41-70.
STOTZ, D. F., S. M. LANYON, T. S. SCHULENBERG, D. E. WILLARD, A. T. PETERSON & J. W. FITZPATRICK (1997). An avifaunal survey of two tropical forest localities on the middle Rio Jiparanã, Rondônia, Brazil. Pp. 763-781. In: J. V. Remsen, Jr. (Ed.) Studies in Neotropical Ornithology honoring Ted Parker. Washington: American Ornithologists’ Union (Ornithological Monographs No.48)
WHITNEY, B. M. & J. ALVAREZ A. (1998). A new Herpsilochmus antwren (Aves: Thamnophilidae) from northern Amazonian Peru and adjacent Ecuador: the role of edaphic heterogeneity of terra firme forest. Auk 115(3): 559-576.
WHITNEY, B. M., M. COHN-HAFT, G. A. BRAVO, F. SCHUNCK & L. F. SILVEIRA (2013). A new species of Herpsilochmus antwren from the Aripuanã-Machado interfluvium in central Amazonian Brazil. Pp. 277-281 In: del Hoyo, J., A. Elliott, J. Sargatal, and D. A. Christie (eds.) (20 13). Handbook of the Birds of the World. Special Volume: New Species and Global Index. Barcelona: Lynx Edicions.
WHITNEY, B. M. , J. F. PACHECO, D. R. C. BUZZETTI & R. PARRINI (2000) Systematic revision and biogeography of the Herpsilochmus pileatus complex, with description of a new species from northeastern Brazil. Auk 117(4):869-891.
José Fernando Pacheco, September 2013
Comments from Stiles: “YES. Genetic, vocal and morphological data coincide, and this proposal falls in line with recent recognition of more species in Herpsilochmus (due to splits and recent descriptions), as well as the recognition of the importance of major rivers in promoting isolation and speciation in the lower Amazon basin for several groups in this family of weakly flying, sedentary species.”
Comments from Zimmer: “YES. Vocal distinctions from congeners are diagnostic and genetic data are convincing. The minor plumage distinctions relative to some congeners are consistent with the generally conservative nature of plumage divergence in the genus as a whole. This is another species that I have seen and tape-recorded along the rio Roosevelt, and all of my observations regarding distribution, ecology, voice and morphology of stotzi are consistent with those described in Whitney et al. (2013).”
Comments from Jaramillo: “YES – This seems like a solid new species.”
Comments from Robbins: “YES, for recognizing Herpsilochmus stotzi, as the data are consistent with the treatment of other recognized species in this plumage conserved genus.”
Comments from Pérez-Emán: “YES. Although without a formal analyses on morphology and vocalizations, data presented by Whitney et al. (2013) on these characters, as well as molecular information, are consistent with species level differences in this genus.”
Comments from Remsen: “YES. Vocal data are convincing for species rank. The % sequence divergence, however, is basically irrelevant – this metric is essentially useless for assigning taxon rank at this level – all it tells us is very roughly how long the population has been separated from its sister and is also influenced by effective population size. What counts is not degree of divergence in neutral loci, but degree of divergence in characters that influence gene flow.”