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.
Literature
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.
YES.
________________________________________________________________________________________________________
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."