Proposal (492) [revised] to South American Classification Committee
Revise
generic boundaries in the Buteogallus group (2)
Effect on South American CL:
This merges Harpyhaliaetus and “Leucopternis” (the temporary designation
for former Leucopternis species
definitely not members of that genus) into Buteogallus,
except for “L. plumbeus”, which would
become Cryptoleucopteryx plumbeus.
Background
& New Information: Our current classification looks like this
after passage of proposal 460, which moved true Leucopternis and relatives near Buteo:
“Leucopternis” plumbeus Plumbeous Hawk
“Leucopternis” schistaceus Slate-colored
Hawk
“Leucopternis” lacernulatus White-necked
Hawk
Buteogallus anthracinus Common Black-Hawk
Buteogallus aequinoctialis Rufous Crab Hawk
Buteogallus urubitinga Great Black-Hawk
Buteogallus meridionalis Savanna Hawk
Harpyhaliaetus solitarius Solitary Eagle
Harpyhaliaetus coronatus Crowned Eagle
For
several years, we’ve had plenty of indication that the current boundaries of
genera in the vicinity of Buteogallus
in our current classification are a mess.
Raposo do Amaral et al. (2009) have produced a comprehensive phylogeny
of buteonine hawks, and their data will form the primary basis for this
proposal. Findings from earlier papers
(see Notes below) are largely consistent with Raposo do Amaral et al. (2009)
and will not be discussed further. Two
of the relevant Notes from our SACC classification are:
14b. Buteogallus urubitinga was
formerly treated in the monotypic genera Urubitinga
(e.g., Hellmayr & Conover 1949) or Hypomorphnus
(Pinto 1938, Friedmann 1950, Phelps & Phelps 1958a), but see Amadon (1949) and Amadon & Eckelberry (1955)
for rationale for placement in Buteogallus. Genetic data (Lerner &
Mindell 2005), however, indicate that Buteogallus urubitinga and B.
anthracinus are not sisters and that the former is more closely related to Harpyhaliaetus
(see also Amadon 1949, Raposo et al. 2006). Raposo do Amaral et al. (2009)
recommended that they be treated in the genus Urubitinga. SACC proposal to revise generic limits in Buteogallus and relatives did not pass.
15. Buteogallus meridionalis was
formerly (e.g., Pinto 1938, Hellmayr & Conover
1949, Friedmann 1950, Phelps & Phelps 1958a, Meyer de Schauensee
1970) placed in the monotypic genus Heterospizias, but most recent
classifications follow Stresemann & Amadon (1979) and Amadon (1982) in
merging this into Buteogallus. <incorp. Griffiths
(1994)>
Recent genetic data (Raposo et al. 2006, 2009, Lerner
et al. 2008) indicate that Buteogallus
is paraphyletic with respect to Harpyhaliaetus and certain Leucopternis.
SACC proposal to revise generic limits in Buteogallus and relatives did not pass. Buteogallus meridionalis was
formerly (e.g., Peters 1931, Friedmann 1950) placed in the subfamily
Accipitrinae, but Plótnik (1956a) showed that morphological data favored
placement in the Buteoninae, as confirmed by genetic data (Lerner et al. 2008,
Raposo do Amaral et al. 2009).
Raposo
do Amaral et al.’s (2009) taxon sampling (105 specimens, 54 species) and gene
sampling (6000 bp of 9 genes, mitochondrial and nuclear) is exemplary. I doubt that anyone will produce a better
data set anytime soon. This proposal
deals only with their Group H, whose monophyly has excellent support; the
relevant portion of their tree (from their Fig. 3) is pasted in here:
Therefore,
the problems in current classification are even worse than revealed in earlier
papers, with most species requiring a change in genus. Raposo do Amaral et al. had to name two new
genera to avoid combining all species into one large, heterogeneous Buteogallus. The latter solution is actually an
alternative to be explored if this proposal does not pass. Group H includes all the taxa previously
associated with Buteogallus, within
which generic limits have been historically fluid, and adds in three species
from Leucopternis, two of which are
dark like most of the Buteogallus
group but also one (lacernulatus)
that has more typical black-and-white Leucopternis
plumage. What a mess. At least one of the former Leucopternis, schistaceus, has a riverine habitat like its new sister taxa, Buteogallus sensu stricto.
Analysis
and Recommendation:
Virtually every critical node in Group H’s tree has strong support. Therefore, the only point of real discussion
is the subjective exercise of how broadly to delimit the genera. Raposo do Amaral et al. have defined these
very narrowly, but a proposal (459) to adopt that classification (see
below) did not pass.
Cryptoleucopteryx
plumbea (the new genus is feminine)
Buteogallus anthracinus (includes “subtilis”)
Buteogallus aequinoctialis
Buteogallus schistaceus
Heterospizias meridionalis
Amadonastur lacernulatus
Urubitinga urubitinga
Urubitinga solitarius
Urubitinga coronatus
The
option at the other extreme would be to expand Buteogallus to include all nine species in Group H. However, I am persuaded by the comments (see 459) of Kevin Zimmer and Bret Whitney, and
by Gary Stiles’s comments below (originally submitted as a NO vote to the
previous version of this proposal that was for a single broad Buteogallus) that the outlier, “L.” plumbeus,
placed in a newly described genus Cryptoleucopteryx,
merits a monotypic genus. Although no
single character diagnoses it, it has a unique combination of characters, and plumbeus is also an oddball in terms of
voice and behavior.
A
YES vote would be to adopt the following classification by merging Harpyhaliaetus and two “Leucopternis” into Buteogallus to produce the following classification (which includes
a minor sequence change mentioned by Manuel in 459):
Cryptoleucopteryx plumbea
Buteogallus schistaceus
Buteogallus anthracinus
Buteogallus aequinoctialis
Buteogallus meridionalis
Buteogallus lacernulatus
Buteogallus urubitinga
Buteogallus solitarius
Buteogallus coronatus
As
expected from a decision that is largely subjective, the comments on 459 were all over the place in terms of
preference, but at least a couple of you were in favor of broad Buteogallus. A point against such a treatment is that if
you look at the big tree in Raposo et al., the node (H) that unites a broad Buteogallus is deeper than the points on
the x-axis (substitutions/site) as the nodes that mark most generic limits we
adopted for the buteonines in proposal 460; so based purely on comparable
degree of genetic differentiation, a broad Buteogallus
is within those limits but at the extreme.
On the other hand, the depth of that node is driven entirely by plumbeus – if not for that species, the
node would be at the opposite end of the range of the depths that mark generic
boundaries in the buteonines. To
maximize consistency based on genetic differentiation, a solution would be to
adopt Cryptoleucopteryx for plumbeus and keep the rest in Buteogallus (a solution mentioned by
Doug in his comments on 459).
Literature Cited:
RAPOSO DO AMARAL, F.,
F. H. SHELDON, A. GAMAUF, E. HARING, M. RIESING, L. F. SILVEIRA, AND A.
WAJNTAL. 2009. Patterns and processes of diversification in
a widespread and ecologically diverse avian group, the buteonine hawks (Aves,
Accipitridae). Molecular Phylogenetics and Evolution 53: 703-715.
Van
Remsen, August 2011
____________________________________________________________________________________________________________
Comments from Stiles: “YES.
“1. I definitely favor placing plumbeus in Cryptoleucopteryx, based largely on Kevin`s comments on the
previous proposal and the large genetic distance to the rest of the "Buteogallus group". I am not
disturbed by the "lack of a single diagnostic character": a unique
combination of characters serves to diagnose many avian genera. The single-character
requirement harks back to a century ago, when such characters in taxonomic keys
dictated generic boundaries - rather like putting the cart before the horse.
Actually, we haven't been all that consistent in use of genetic vs.
morphological-ecological-behavioral features and generic boundaries in any case
... after all, we recognized Cantorchilus
based on genetics when the morphological evidence was, as far as I could tell,
zero, and did not recognize Diglossopis
as separate from Diglossa based on
relatively short genetic distances but in the face of considerable
morphological, behavioral and ecological differences. And there have yet to be advanced good
morphological diagnoses for some genera in Furnariidae (e.g., the Asthenes-Schizoeaca assemblage). So, it comes down to rather subjective
decisions in any case regarding how to weigh the different types of evidence
when they do not coincide neatly.
“2. Regarding placing all the remainder
of this group in a broad Buteogallus,
I could buy it, albeit with some reservations.
The only real oddball (at least in terms of appearance) is lacernulatus, but genetics strongly
favors including it, especially if we also include meridionalis, which I find much less surprising: its juvenile
plumage is decidedly buteogalline, its coloration as adult is not so unlike aequinoctialis, its vocalizations are
also not greatly unlike some Buteogallus. Although more terrestrial than others, urubitinga also forages much on the
ground and has decidedly longish legs as well. I have already remarked
upon the resemblance of solitarius
and urubitinga, such that I see no
objection to considering these as congeners, which pretty much bridges the
gaps; so, unless there is strong support for the original proposal of Raposo et
al. (including two monotypic genera for meridionalis
and lacernulata and separating Urubitinga), the next best choice would
indeed be two genera: Cryptoleucopteryx
and Buteogallus.”
Comments from Robbins: “YES. This is a subjective decision, but as I
mentioned in my comments on proposal # 459, the vocal and morphological
variation within a broadly defined Buteogallus
are no more than that found within Buteo.
With regard to genetic variation and consistency among nodes in taxonomy
and nomenclature, I'm fine with placing plumbeus
in a monotypic genus. This is somewhat
analogous with what we did in naming a new genus for the highly genetically
divergent, but morphologically indistinct (vocalizations are still unknown),
Malagasy Gactornis "Caprimulgus" enarratus (although that was a very long branch).”
Comments from Pacheco: “YES. Um
relutante sim. Eu, particularmente, preferia o arranjo com utilização de mais
gênero tal qual proposto no artigo de Raposo do Amaral et al. 2009. Concordo, todavia, que essa solução é factível em
vista da árvore produzida a partir da mesma análise.”
Comments from Cadena: “YES. I am not a great fan of monotypic
genera; whenever possible, unless one is truly dealing with hoatzin-like oddballs,
I prefer having genera with more than one species. I believe this increases the
information content of the classification because one immediately knows that
two species in the same genus are close relatives, whereas if one has two
separate monotypic genera for sister lineages, their close affinity is
essentially unknowable based on the names alone. Thus, I like the expanded Buteogallus over the use of the two
monotypic genera Amadonastur and Heterospizias. I'll take other's word
that plumbea is the hoatzin
equivalent in these raptors (I am afraid I do not know all these taxa all that
well), so I am OK with Cryptoleucopteryx.”
Comments from Jaramillo:
“YES. I think that this is a good resolution to
this problem. Using a monotypic genus for plumbeus is the better
solution as opposed to a broad and genetically too (?) divergent single Buteogallus
that includes all of the species. Having a broad Buteogallus is a
benefit, and a better solution in my mind, than is separating it out into 3-4
genera.”
Comments from Zimmer: ““YES. I agree with Fernando in having a preference for more narrowly defined genera, although readily acknowledge that having a bunch of monotypic genera isn’t all that informative. I think Van has come up with a good compromise in this case, by recognizing the distinctiveness of plumbeus by placing it in a monotypic genus Cryptoleucopteryx, and placing everything else in a broadly defined Buteogallus. As Gary points out, it is not much of a stretch to see the similarity of meridionalis to urubitinga (ecologically, morphologically [especially as regards juvenile plumage], vocally) and to aequinoctialis (plumage characters of adults and juveniles). Same goes for the two species of Harpyhaliaetus and for schistaceus and anthracinus. The one that still doesn’t feel right is lacernulatus (which is pretty different morphologically, is a forest interior hawk that frequently soars, etc.), but then we have to contend with the genetic data and the apparent close relationship between lacernulatus and meridionalis. All in all, I think this is a good compromise.”