Proposal (588) to South American Classification Committee
Split Hypocnemis striata into two species
Effect on SACC: If adopted, as recommended by Whitney and colleagues (2013), one species would be added to the South American checklist by splitting Hypocnemis striata into two species: H. striata Spix, 1825, and the newly described H. rondoni.
Background: During survey work near Manicoré, Amazonas, Brazil, in June 2000, Bret Whitney and Mario Cohn-Haft recorded vocalizations of what was then considered Hypocnemis cantator and immediately recognized that the calls of this population were distinct from those of other populations. Collection of a specimen was not feasible at the time, and vocalizations of only two individuals were recorded. Consequently, when species limits within the complex were examined (Isler et al. 2007), the population could not be described and was identified as taxon novum. Because the male loudsong was more similar to that of the neighboring subspecies of H. striata than to H. ochrogyna, its other neighbor east of the Rio Madeira, the population was considered a subspecies of the former, recognizing that collecting specimens and obtaining more vocal recordings would be required to determine its taxonomic status.
Newly published information: As a result of the requisite collection and analysis of specimens, vocal recordings, and other behavioral information, Whitney, Isler, Bravo, Aristizábal, Schunck, Silveira, Piacentini, Cohn-Haft, and Rêgo (2013) confirmed the distinctiveness of this population and described it as a new species, Hypocnemis rondoni (Manicore Warbling-Antbird). Its distinctive call has now been recorded from between the right bank of the Rio Madeira and the left bank of Rio Aripuanã in the state of Amazonas, Brazil, upriver to the Rio Roosevelt in extreme northwest Mato Grosso and the Rio Machado at the extreme northern edge of the state of Rondônia.
Maximum-likelihood and Bayesian analyses of mtDNA showed that H. rondoni is sister to H. ochrogyna from which it is ~4% divergent and that this clade is ~5% divergent from H. striata. Comparison of 58 recordings of H. rondoni, 25 of which contained calls, confirmed the earlier finding (Isler et al. 2007) that it is diagnosable by voice from all other members in the H. cantator complex.
Morphological and plumage differentiation is weak as is typical of several allospecies in the complex, but vocal differentiation, especially in calls, provides a strong measure of species status in the complex. This is exemplified by H. peruviana and H. subflava, two broadly sympatric species in the complex whose loudsongs are similar but whose calls differ completely. Vocalizations of H. rondoni differ from those of its sister species, H. ochrogyna, not only in its calls, but its loudsongs as well. Possible sympatry of the two species is suggested by the recording of loudsongs typical of each species at a site on the right bank of the Rio Roosevelt.
Recommendation: I recommend a "YES" vote on accepting this antwren as a new species to our list, based on vocal and genetic distinctions found between H. rondoni and the related taxa
Isler, M. L., P. R. Isler, and B. M. Whitney. 2007. Species limits in antbirds (Thamnophilidae): the Warbling Antbird (Hypocnemis cantator) complex. Auk 124:11–28.
Whitney, B. M., M. L. Isler, G. A. Bravo, N. Aristizábal, F. Schunck, L. F. Silveira, V. de Q. Piacentini, M. Cohn-Haft, and M. A. Rêgo. 2013. A new species of antbird in the Hypocnemis cantator complex from the Aripuanã-Machado interfluvium in central Amazonian Brazil. In: del Hoyo, J., Elliot, A., Sargatal, J., & Christie, D.A. (Eds), Handbook of the Birds of the World. Special Volume: New Species and Global Index. Lynx Edicions, Barcelona, Spain, pp. 282–285.
Morton Isler, October 2013