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 R’o Caroni, a tributary of the lower Orinoco, Bol’var, that they described as a new species-level taxon, Amaurospiza carrizalensis. It is known from two males and a female, all deposited at Colecci—n Ornitolog’a 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 gˇnero y el hecho de haber satisfecho a los revisores de Auk, parecen ser suficientes para ser considerada especie. "