Proposal (630) to South American Classification Committee

 

Treat Myiothlypis roraimae as separate species from M. bivittata (revisited)

 

In another lifetime, the committee rejected (proposal 67) the treatment by Hilty (2003) of considering the highly distinct, but morphologically very similar, Tepui endemic Myiothlypis (bivittata) roraimae as a separate species from southern Andean M. bivittata.  The committee unanimously rejected the proposal because no data were presented in Hilty that supported the split.  However, as has come to be expected, Hilty has again been proven to be correct.  Recently, I finally heard and audio recorded roraimae on Ayanganna tepui in Guyana, and I was stunned at how different the song is from southern bivittatus.  Of course, this has been apparent for some time as song recordings have been available online at xeno-canto and the Macaulay Library (Cornell). The songs of the two are so different that one would question whether they are even sister taxa (molecular data are equivocal; Lovette et al. 2010).  If indeed molecular data eventually demonstrate that they are sister taxa, then the song of these two taxa are as different as any pair of sister species within Myiothlypis.  Comparison of the following song audio recordings provides evidence on how different these two are. Note that I have given just a few catalog #s from xeno-canto (there are many more) and because of the ease of examining spectrograms on xeno-canto vs. Macaulay, only xeno-canto numbers are given. However, many recordings that demonstrate this are available online at Macaulay (e.g., http://macaulaylibrary.org/audio/174870).

 

M. roraimae: XC6178, XC122857, XC8248

M. bivittata: XC33197, XC13238, XC14490

 

   In addition to the vocal data, these two taxa are very different in their ecology and behavior.  Based on my experience on two Guyana tepuis (Roraima and Ayanganna), roraimae forages from mid-level up to the subcanopy in very humid (often moss-laden), montane forest (800-1800 m in Venezuela; Hilty 2003), whereas bivittatus is a strictly understory bird in the southern Andean foothills (7501500 m in Peru; Schulenberg et al. 2007). Bivittatus is often associated with bamboo (pers. obs.; Schulenberg et al. 2007).  In the Guyana tepuis, roraimae has not been found in association with bamboo, and Hilty (2003) stated shows no special affinity for bamboo in Venezuela.

 

Thus, I highly recommend that roraimae be treated as a species.

 

Hilty, S. L. 2003. Birds of Venezuela. Princeton University Press, Princeton, New Jersey.

Lovette, I.J., J. Prez-Emn, J.P. Sullivan, R.C. Banks, I. Fiorentinoa, S. Crdoba-Crdoba, M. Echeverry-Galvis, F.K. Barker, K.J. Burns, J. Klicka, S.M. Lanyon, and E. Bermingham. 2010. A comprehensive multilocus phylogeny for the wood-warblers and a revised classication of the Parulidae (Aves). Molecular Phylogenetics and Evolution 57:753770

 

Mark Robbins, May 2014

 

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Comments from Stiles: YES. I have heard the recordings on Xeno-canto recommended by Mark and they are indeed VERY different certainly different enough to provide potentially effective isolating mechanisms.  Given the huge range disjunction between these two and the ecological differences, species status for roraimae seems eminently logical.  Im not especially bothered by the morphological similarities, as quite a few species of the Basileuterus-Myiothlypis assemblage have rather similar plumages, basically variations on a common theme (olive and yellow with striped heads), so plumage homoplasy would not be all that surprising.

 

Comments from Pacheco: YES.  In light of the distinctions mentioned in vocal repertoire and behavior.

 

Comments from Nores: YES. The songs of these two taxa are quite different.  Note: in Argentina and southern Bolivia, M. bivittata is very common and is not associated with bamboo.

 

Comments from Remsen:  NO, but strictly on a technicality.  I am 100% convinced that these should be treated as separate species.  However, we have rejected many proposals because the evidence has not been published.  The recordings are available, yes, but not published per se.  As productive as Mark is, it would take him about an hour to put all this into a 1-page note for a bird journal.  We need to stick to our high standards.  There arte excellent reasons to maintain them.

 

Comments from Areta: NO. I agree with Van's points. Jorge Prez-Emn, Irby Lovette and I have been working for some time on a paper on this issue, having studied specimens, vocalizations and including extensive genetic sampling of the species in the bivittatus group.  We hope to publish the results (fully supporting species status for roraimae) at some point.  Until then, there is no convincing thorough published study for the split.  Nores's comment on the lack of preference for bamboo in nominate bivittatus agrees with my experience.

 

Comments from Cadena: NO, for the same reasons mentioned by Van. I really think we need to stick to published analyses as we have done for years. This is not only because of the value of peer-review (which we all know may fail sometimes), but especially because published papers include quantitative analyses absent from proposals such as this one. I think a case like this proposal is a no-brainer (these are most certainly different species and one may argue that throwing sophisticated analyses at cases like this is like killing flies with machine guns), but relying solely on our ears and eyes (in eyeballing sonograms) with no quantitative analyses put us on a rather slippery slope not far from the practices of field-guide taxonomy which we have long criticized and which were part of the reason committees like SACC were created. With a few hours of effort to actually measure traits on an adequate number of sonograms (something students could help with), to conduct statistical analyses, and to put together all the relevant data, proposals like this one could be turned in to publications that enter the long-term record of scientific literature.

 

Comments from Prez-Emn: NO following Vans points. It would be better to have a study formally treating this potential split.

 

Comments from Stotz: NO.  I think that these are very likely different species, but given that people are working on this issue, we should wait for that publication.