Proposal (56) to South American Classification
Committee
Continue to recognize
broad genus Amazilia
PROPOSAL: Continue to recognize a large genus Amazilia,
recently split into several genera (Amazilia, Agyrtria, Polyerata,
Saucerrottia) by Weller and Schuchmann. There are basically two reasons for
not recognizing this split: the lack of concrete published evidence, and two
(admittedly) unpublished studies that will hopefully shed more light upon this
problem. One of these is a morphological study of mine using a much more
extensive list of external characters than other such studies. To date I have
data for some 120 species, including a dozen or so Amazilia (sensu
lato). It may indeed be possible to break the genus into several more cohesive
groups, but the limits of these do not coincide with those of Schuchmann-Weller
in several cases. The other study is a much more detailed phylogeny of the
Trochilidae by McGuire and Altshuler, now in progress. This study suggests that
Amazilia is indeed polyphyletic, but again it is not certain whether the
breaks will fall where Schuchmann-Weller place them. It should be emphasized
that the characters cited explicitly by Schuchmann and Weller are almost
exclusively those of plumage pattern and in some cases biometrics, using
traditional mensural characters. The assumption is clearly that plumage
characters are more conservative and hence better indicators of relationship
than other external or genetic characters; in fact, Schuchmann (1999)
explicitly questions and discards genetic studies when they fail to support his
"eleven major clades". These clades are stated to be based upon a
broad spectrum of behavioral, biogeographic, vocal and morphological features
but virtually all of this evidence remains unpublished. In fact, in the case of
Amazilia they develop biogeographic hypotheses for each of the new
genera, then in effect use these hypotheses to support the splits, which seems
circular to me. Hence, I propose that until more evidence is forthcoming (in
particular genetic data), the splitting up of Amazilia as proposed in
HBW is unwarranted.
Gary Stiles, August
2003
Comments from Remsen: "I vote YES on
this proposal. Whether Amazilia can be subdivided is of less interest to
me than whether the component taxa form a monophyletic unit; if they do, then
recognition of smaller genera is really a matter of taste (assuming each of
those is also monophyletic). If Amazilia is para- or polyphyletic, then
of course this must be reflected in generic reallocation. However, there is
essentially no published information to support this, and whether the
monophyletic groups conform to those proposed by HBW and earlier classifications
remains to be seen."
Comments from Silva: "Yes. I would
prefer to see more published studies about this genus. So far, there is not
enough evidence to propose any change."
Comments from Nores: "[YES] Si. Los comentarios de Stiles son muy convincentes, y hasta tanto no se
publiquen trabajos más fundamentados parece mejor no separar el género."