Proposal (336) to South American Classification Committee
Move Sapayoa aenigma to Eurylaimidae
Sapayoa aenigma, the Sapayoa (AOU 1998), is a small passerine resident in a narrow zone of rainforest in Panama, Colombia, and Ecuador. Described by Hartert (1903), who found it "difficult to place in the system", Sapayoa, in keeping with its specific name, has long been a taxonomic puzzle. After much study, Hartert concluded that it was best placed in the New World suboscine family Pipridae (the manakins), part of the tyrannoid group of suboscines. This has been the generally prevailing view over the past century (e.g., Meyer de Schauensee 1970, Traylor 1979), although Prum (1990), based on study of morphological characters, suggested that Sapayoa might be more closely allied to the Tyrannidae (tyrant-flycatchers).
Lanyon (1985), in an electrophoretic study of the Tyrannoidea, found Sapayoa to be only distantly related to the other taxa studied, and concluded that the true affinities of Sapayoa may be outside the tyrannoids. Sibley and Ahlquist (1990) included Sapayoa in their DNA-DNA hybridization experiments, the melting curves of which indicated that it was close to the Old World suboscines (Eurylaimides: broadbills, asities, and pittas), but were evidently uncertain of their data and excluded it from their phylogenetic analyses and trees. Subsequently, Sibley and Monroe (1990), unable to place it with confidence among any group of suboscines, considered it a separate family incertae sedis. Sapayoa was also considered incertae sedis in the AOU Check-list 1998, and provisionally placed between the Tyrannidae and Cotingidae within the Tyrannoidea.
Using DNA sequence data, Fjeldså et al. (2003) and Chesser (2004) clearly showed that Sapayoa is more closely related to the Old World suboscines than to any New World suboscine group. Irestedt et al. (2006) and Moyle et al. (2006) further showed that it is embedded within the Old World suboscine family Eurylaimidae (broadbills). Both studies found the Old World broadbill (and asity) species to form two sister clades, one consisting of Calyptomena and Smithornis, the other of Eurylaimus, Cymbirhynchus, Serilophus, Corydon, Psarisomus, Pseudocalyptomena, Neodrepanis, and Philepitta. Irestedt et al. (2006) found Sapayoa to be sister to the Calyptomena-Smithornis clade, whereas Moyle et al. (2006) found Sapayoa to be sister to the second clade.
Proposal: Change the taxonomic placement of Sapayoa aenigma to Eurylaimidae and insert this species and family before Furnariidae in the Check-list.
Recommendation: Vote YES. The only real alternative to this, given the uncertainty of Sapayoa's relationships within the family, would be to create a separate family for Sapayoa, which would necessitate a split of the Eurylaimidae into three families: Eurylaimidae, Calyptomenidae, and Sapayoidae. The splitting of the Eurylaimidae is primarily an Old World issue and my view is that we should follow the traditional position, in which all broadbills constitute the single family Eurylaimidae, rather than making new policy. Dickinson (2003) placed Sapayoa in the separate family Sapayoaidae (sic) while maintaining the single broadbill family Eurylaimidae; this arrangement is not supported by the current data.
Chesser, R. T. 2004. Molecular systematics of New World suboscine birds. Molecular Phylogenetics and Evolution 32: 11-24.
Fjeldså, J., et al. 2003. Sapayoa aenigma: a New World representative of 'Old World suboscines'. Proc. R. Soc. Lond. B (Suppl.) 270: S238-S241.
Hartert, E. 1903. On a remarkable new oligomyodian genus and species from Ecuador. Novit. Zool. 10: 117-118.
Irestedt, M., et al. 2006. Nuclear DNA from old collections of avian study skins reveals the evolutionary history of the Old World suboscines (Aves, Passeriformes). Zool. Scripta 35: 567-580.
Lanyon, S. M. 1985. Molecular perspective on higher-level relationships in the Tyrannoidea (Aves). Syst. Zool. 34: 404-418.
Meyer de Schauensee, R. 1970. A Guide to the Birds of South America, Academy of Natural Sciences of Philadelphia, PA.
Moyle, R. G., et al. 2006. Phylogeny and evolutionary history of Old World suboscine birds (Aves: Eurylaimides). Amer. Mus. Novitates 3544: 1-22.
Prum, R. O. 1990. A test of the monophyly of the manakins (Pipridae) and of the cotingas (Cotingidae) based on morphology. Occas. Pap. Mus. Zool. Univ. Michigan 723: 1-44.
Sibley, C. G., and J. E. Ahlquist. 1990. Phylogeny and Classification of Birds, Yale Univ. Press, New Haven, CT.
Sibley, C. G., and B. L. Monroe. 1990. Distribution and Taxonomy of Birds of the World, Yale Univ. Press, New Haven, CT.
Traylor, M. A. (ed.) 1979. Check-list of Birds of the World, Vol. 8. Mus. Comp. Zool., Cambridge, MA.
R. Terry Chesser, March 2008
Note: This proposal passed NACC unanimously, with the following comments:
YES. The molecular evidence for this is convincing, and limited morphological data (some unpublished) support it as well.
YES. Independent genetic data sets support this placement.
YES, although it's hard to think of Broadbills as anything other than Old World.
YES, although I think it's likely that Eurylaimidae will be split into three families eventually.
YES. I'm guessing that this will ultimately go the three-family route, though.
YES. It's no harder for me to accept this than that all trogons (with a similar global distribution) for example are in a single family.
YES. Two independent datasets now support inclusion in Eurylaimidae, and maintenance of Sapayoidae would render Eurylaimidae paraphyletic. [As an aside, Burt Monroe predicted all this 20 years ago].
YES, although this makes no biogeographic sense to me.
YES. I really don't want to vote in favor of this, it just seems too bizarre. But Sapayoa has floated around for a couple of decades without a home and the molecular data looks strong. It just seems hard to imagine biogeographically.
Comments from Zimmer: "YES. In spite of the biogeographical questions that it raises, the genetic evidence appears strong. Even if Eurylaimidae as currently constituted ends up split, I think the best thing to do right now is move Sapayoa there, rather than putting it in its own family."
Comments from Robbins: "YES. I find Terry's rationale for treating Sapayoa within the Eurylaimidae as the most prudent thing to do as this point."
Comments from Stotz: "YES. This is pretty amazing biogeographically, but makes some sense morphologically, and Sapayoa has been a problem for quite some time. Eurylaimidae seems like the best choice among the available options that reflect the genetic work."
Comments from Stiles: "YES. The phylogenetic data state overwhelmingly that Sapayoa is embedded in Eurylaimidae, not peripheral or basal to it; if Eurylaimidae were to be split, it would go with one of the families so formed - in either case, there seems no justification from phylogeny to place it in a monotypic family so either way, Sapayoidae would fall. If we have to change the family name at some point due to such a split, so be it - for now, evidence indicates placing it in a broad Eurylaimidae. The biogeographical aspect is intriguing but really peripheral in this context."
Comments from Nores: "YES. Es evidente su relación con los "Old World suboscines" como lo demuestran los análisis moleculares, aunque llama la atención que Irestedt y Moyle lo incluyen en diferentes clades de "Old World broadbill", lo que agrega una duda más sobre la fidelidad de los estudios moleculares. Además, me parece muy difícil que una especie como esta (que habita la parte densa baja de selvas tropicales) pueda estar íntimamente relacionada con una familia tan lejana de África/Asia. Por esta razón, yo voto también en crear una nueva familia para esta especie: Sapayoidae. Un caso muy similar al de Donacobius atricapillus."