Download Proposal (# 74 ) to South American Checklist Committee

Proposal (# 74) to South American Checklist Committee
Recognize Amaurospiza carrizalensis
Effect on South American CL: This proposal adds a newly described species to
our official list.
Background: Lentino and Restall (2003) discovered a new population of
Amaurospiza in northern Venezuela on the Río Caroni, a tributary of the lower
Orinoco, Bolívar, that they described as a new species-level taxon,
Amaurospiza carrizalensis. It is known from two males and a female, all
deposited at Colección Ornitología Phelps in Caracas. Photos of hand-held male
and female appear in the paper (and a painting of a pair is on the cover of that
issue of the Auk). The authors compared their type series to specimens of the 5
other named taxa of Amaurospiza. They concluded that the new taxon deserves
species rank because it differs from the two Amaurospiza taxa currently treated
as species by at least as much as those two species do from one another. It has
the largest bill and most pointed wing of any taxon in the genus; males differ from
other Amaurospiza in "density of coloration and black flammulations on the
breast." The two other species of Amaurospiza in South America are found
western Ecuador (A. concolor aequatorialis) and the Atlantic Forest region (A.
moesta); biogeographically closer might be Panamanian populations of A. c.
concolor; in any case, carrizalensis is remarkably isolated from congeners.
As with congeners, carrizalensis was found in bamboo thickets. The river island
that is the type locality has evidently now been cleared, although similar habitat
exists nearby.
Analysis: This new taxon is clearly an Amaurospiza and diagnosable from other
described taxa in the genus. The only question is whether it deserves species
rank. Ideally, a larger series of specimens and detailed comparisons of
vocalizations would support the assignment of species rank to carrizalensis.
Given what is known, however, it would be difficult to assign carrizalensis to
either A. concolor or A. moesta. Because it differs more from either concolor or
moesta than do those two do from each other in terms of morphology (and
coloration?), I think the authors were justified in assigning species rank.
Recommendation: YES, recognize as species, especially because it is not clearly
assignable to either species-level taxon in Amaurospiza.
Literature Cited:
LENTINO, M., AND R. RESTALL. 2003. A new species of Amaurospiza blue
seedeater from Venezuela. Auk 120: 600-606.
Van Remsen, November 2003
PS: The English name proposed by the authors, "Carrizal Blue Seedeater," will
need to be modified, because A. concolor is "Blue Seedeater." I'll work on
proposal for "Carrizal Seedeater" if this one passes.
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Comments from Robbins: "Really there is no option here, unless one lumps all
the South American Amaurospiza. Thus, I vote 'YES' for recognizing
carrizalensis as a species."
Comments from Zimmer: "YES. The range disjunction is so large, that I can't see
this form being anything other than specifically distinct, even if it is based on a
small sample size. It appears to be at least as different morphologically as are
the other two species."
Comments from Jaramillo: "YES morphologically distinct, and population
strongly isolated from all others in genus. Seems like the clear course in this
situation."
Comments from Nores: "YES. Acepto reconocer a Amaurospiza moesta como
especie. Los caracteres dado por los autores, la poca posibilidad de asignarla a
otra especie del género y el hecho de haber satisfecho a los revisores de Auk,
parecen ser suficientes para ser coniderada especie. "