Proposal (74) to South American Classification 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.
________________________________________________________________________________________
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 considerada especie. "