Proposal (480) to South American Classification Committee

Place Sapayoa aenigma in its own family, Sapayoidae

[Note from Remsen: this proposal passed the North American Classification Committee (10 to 1) and is posted here with the permission of its authors]:

Background: The SACC currently places the Sapayoa (Sapayoa aenigma) in the Eurylaimidae (Banks et al. 2008). However, the taxonomic position of the Sapayoa has only recently been resolved. This species was long considered an aberrant member of the Pipridae (manakins), as evidenced by the old common name Broad-billed Manakin (Snow 2004). Peculiarities in its morphology precluded definitive placement in any group of the suboscines, although work by Prum (1990) placed it near the Tyrannidae.

Early genetic studies were unable to place the Sapayoa in a specific group. Lanyon (1985), in a study of tyrannoids using protein electrophoresis, found that the Sapayoa did not belong with any of the sampled species, which included representatives of the Pipridae, Tyrannidae, Cotingidae, and Tityridae. Instead, the Sapayoa was found to be sister to the other tyrannoids sampled (Lanyon 1985). Sibley and Ahlquist (1990) considered the Sapayoa as incertae sedis; however, they suggested that it might be closely related to the Old World suboscines (Sibley 1994).

It was not until the use of DNA sequence data that the taxonomic position of the Sapayoa became clear. Based on several studies, the Sapayoa has been found to be closely related to the Old World suboscines, specifically the Eurylaimidae (Fjeldså et al. 2003, Chesser 2004, Irestedt et al. 2006, Moyle et al. 2006). Two primary hypotheses as to its relationships have emerged. The first hypothesis has the Sapayoa as sister to the asities (Philepitta and Neodrepanis) and several broadbill genera (Cymbirhynchus, Psarisomus, Serilophus, Eurylaimus, Corydon, and Pseudocalyptomena), hereafter referred to as the Asian and Grauer’s Broadbills (Moyle et al. 2006). The second hypothesis places the Sapayoa as sister to the Calyptomena and Smithornis broadbills, hereafter referred to as the green and African broadbills (Fjeldså et al. 2003, Irestedt et al. 2006).

Based on these findings, two taxonomic treatments have been proposed. The first is the taxonomy already adopted by the NACC and the SACC, which involves the recognition of a single large Eurylaimidae, within which are placed the Sapayoa, the green and African broadbills, and the asities (Clements 2007, Gill et al. 2009). The second option involves the recognition of four “broadbill” families, including a monotypic Sapayoidae (Dickinson 2003).

Proposal: Based on the available genetic data, the morphological evidence, and the biogeographic patterns, we propose the recognition of a monotypic Sapayoidae, which would necessitate the elevation of the green and African broadbills to family status as the Calyptomenidae (Fjeldså et al. 2003, Chesser 2004, Irestedt et al. 2006, Moyle et al. 2006). Irestedt et al. (2006) proposed this action based on the Sapayoa’s morphological and biogeographical distinctness. In addition, the Sapayoa has undoubtedly been isolated from the rest of the broadbill taxa for quite some time (estimated at 52 million years by Moyle et al. 2006), and its syringeal morphology is quite distinct from that of the other broadbills (Prum 1990).

The inclusion of Sapayoa within the Eurylaimidae also renders the family paraphyletic with respect to the asities (Philepittidae). The asities, a distinctive group of birds endemic to Madagascar, are recognized by most authorities as deserving family rank, and the placement of Sapayoa within the Eurylaimidae requires this family to be included in the larger Eurylaimidae (Dickinson 2003, Irestedt et al. 2006).

The correct name for the family is Sapayoidae, formed by adding the family ending -idae to the stem of the type genus, Sapayo-. Although Dickinson (2003) incorrectly used the name “Sapayoaidae,” and the code does provide for priority in such cases (ICZN 1999), this name was not formally proposed and the appropriate citation for the correct family name (Sapayoidae) is instead Irestedt et al. (2006).

Recommendation: Vote yes to recognize the monotypic family Sapayoidae. The Sapayoa is genetically, morphologically, and biogeographically distinct from the rest of the Old World suboscines. In the Check-list, Family EURYLAIMIDAE: Broadbills would be replaced by Family SAPAYOIDAE: Sapayoa. The sequence of species would not change.

References:

Banks, R.C., Chesser, R.T., Cicero, C., Dunn, J.L., Kratter, A.W., Lovette, I.J., Rasmussen, P.C., Remsen, J.V., Jr., Rising, J.D., Stotz, D.F., and Winker, K. 2008. Forty-ninth supplement to the American Ornithologist’s Union Checklist of North American Birds. The Auk 125:3 758-768.

Chesser, R. T. 2004. Molecular systematics of New World suboscine birds. Molecular Phylogenetics and Evolution 32: 11-24.

Clements, J.F. 2007. The Clements Checklist of Birds of the World. Cornell University Press, Ithaca, NY

Dickinson, E.C. ed. 2003. The Howard and Moore Complete Checklist of the Birds of the World. 3^rd Edition. Christopher Helm, London

Fjeldså, J., et al. 2003. Sapayoa aenigma: a New World representative of 'Old World suboscines'. Proc. R. Soc. Lond. B (Suppl.) 270: S238-S241.

Gill, F., M. Wright, and D. Donsker, D. 2009. IOC World Bird Names (version 2.0)

ICZN. 1999. International Code of Zoological Nomenclature. London.

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.

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. 1994. On the phylogeny and classification of living birds. Journal of Avian Biology 25:2 87-92

Snow, D. 2004. Family Pipridae (Manakins) in: del Hoyo, J., Elliot, A. and Christie, D.A. eds. 2004. Handbook of the Birds of the World. Vol. 9. Cotingas to Pipits and Wagtails. Lynx Edicions, Barcelona

Shawn Billerman & Terry Chesser, 12 May 2011

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Comments from Stiles: “YES. It seems that the sticking point on a broad Eurylaimidae is the obligatory inclusion of the Philepittidae if Sapayoa is also included. Because they are morphologically and biogeographically distinct from everyone else, I find family status for them reasonable; each of the two groups of broadbills sensu strict are also well characterized morphologically, and Sapayoa is also distinctive and has a long history of isolation (back to the Eocene?!) so I find family status for it to be reasonable and informative.”

Comments from Robbins: “YES. Billerman and Chesser provide rationale for treating these four clades as families.”

Comments from Nores: “YES, for all of the reasons stated by Billerman and Chesser. Moreover, taking into account that it is a very sedentary species, it is much more logical biogeographically that it belongs to a monotypic South American family than to a family of Asia and Africa.”

Comments from Cadena: “YES, a bit reluctantly. I might have voted no, but considering that this has already been approved by the NACC I am not sure about fighting against the current. I am fine with treating Sapayoa in its own family and I find the reasons outlined in the proposal quite persuasive, but I also feel that this amounts to making decisions that concern the classification of a large group of Old World birds, which would be split in three different families, and I am not sure A.O.U. committees should be doing things like this. I do not know if there are classification committees focused on that part of the World, but what would happen if specialists in these birds and in that region decide that it is best to merge all species in a single family? Would we have to go back? As an aside, but related note, are there criteria specifying which cases are treated by which A.O.U. committee? I am surprised that considering most of the range of Sapayoa is in South America, this proposal was not presented to the SACC first.”

Comments from Pacheco: “YES. Considero que a solução de uma família monotípica para Sapayoa acomoda melhor os resultados obtidos nos recentes trabalhos.”

Comments from Zimmer: “YES. I think this is the most logical treatment on biogeographic grounds, and it also forces recognition of the distinctiveness of the Philepittidae, which I also see as a good outcome.”

Comments from Pérez-Emán: “A tentative YES as my decision is based only on published phylogenetic relationships and not a real knowledge of the group. Current monophyletic groups support four taxa, one of them the monotypic Sapayoidae. However, although I am sympathetic with it, family ranks based on age and distribution might be a subjective reason to erect a family. Moreover, based on these criteria, one could argue that placement of Pseudocalyptomena in the phylogeny might create the need for new arrangements within this group. This taxon is well distinct genetically from other groups, an old divergent lineage, and biogeographically distinct regarding its closer relatives.”