Proposal (56) to
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are basically two reasons for not recognizing this split: the lack of concrete published evidence, and two (admittedly) unpublished studies that will hopefully shed more light upon this problem.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spectrum of behavioral, biogeographic, vocal and morphological features but virtually all of this evidence remains unpublished.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."