Proposal (144) to South American Classification Committee

 

Split Aglaiocercus berlepschi from Aglaiocercus kingi

 

This proposal would split an isolated representative of the genus Aglaiocercus (in NE Venezuela) from the widespread A. kingi as a separate species-level taxon, A. berlepschi (Venezuelan Sylph).

 

The forms in the genus Aglaiocercus have a very checkered history due mainly to the variations in the colors of the male rectrices and gorgets. Cory (1918) recognized six species: emmae, mocoa, caudata, kingi, berlepschi and coelestis. Hartert (1922), the next reviewer, lumped all into kingii. Berlioz (1940) kept emmae, caudata, and mocoa in kingii but retained coelestis and berlepschi as separate species. Peters (1945) lumped berlepschi into kingi but separated emmae (including mocoa and caudata) and coelestis, but suggested that further analysis might show all to be conspecific. In a more detailed analysis, Zimmer (1952) noted intergradation between kingi and caudata, and kingi and mocoa, as well as between kingi and margarethae (the form nearest to berlepschi but separated by a rather wide gap in N Venezuela, and between margarethae and caudata. He noted several points of resemblance between berlepschi and coelestis (at the opposite extremes of the distribution of the group) and suggested that a paler rufous shade in the underparts of some specimens in the kingi group might suggest intergradation with these white-breasted forms. He therefore returned to the arrangement of Hartert, considering all the forms as races of a broad kingi.

 

Meyer de Schauensee (1966) separated coelestis as a species because of sympatry in SW Colombia (reflected in recently taken specimens of von Sneidern) and differences in female plumages, while retaining the emmae group and berlepschi in kingi (although he did not comment upon the latter). Hilty & Brown (1986) retained the split between kingi and coelestis, providing further details on the sympatry and habitat differences between these forms. Sibley & Monroe (1990) followed suit, and also suggested that the emmae group and berlepschi might also be distinct species.

 

A further detailed analysis by Schuchmann & Duffner (1993) concluded, with Zimmer, that the emmae group belonged with kingi but that both coelestis and berlepschi were entitled to specific status. Their reasons for separating berlepschi were its very different female plumage, certain morphometric differences between it and the closest form of kingi (margarethae) including wing and tail length, a difference between it and all forms of kingi in the breadth of the male outer rectrix (similar to but greater than that between kingi and coelestis, and different tail coloration (blue, vs. green in adjacent forms of kingi), and the gap in distribution (which makes intergradation between these forms unlikely as an explanation for the occasional paler-breasted females in kingi). They noted resemblances between berlepschi and coelestis in several points as well, interpreting these as indication that these two were "relicts of an early dispersion" of the group. Their split of berlepschi was followed by Schuchmann (1999), who illustrated the differences, and by Hilty (2002).

 

Taking all of these differences together, I feel that the evidence definitely does support the split of berlepschi at the species level. The range gap obviates any question of intergradation, but the differences between berlepschi and adjacent forms of kingi equal or exceed those between coelestis and kingii, whose local sympatry and species status seems proven. Whether or not one accepts the evolutionary-biographic scenario of Schuchmann & Duffner, the other differences strongly favor the split, if only to maintain consistency in the species-level taxonomy of the group. I therefore recommend a YES vote on this proposal.

 

Literature Cited:

Cory 1918.

Hartert 1922. Novitates Zool. 29:411.

Berlioz 1940. L'Oiseaux 10: 221-231.

Peters 1945.

Meyer de Schauensee 1966

Hilty & Brown 1986.

Sibley & Monroe 1990.

Schuchmann, K-L. & K. Duffner. 1993. Mitt. Zool. Mus. Berlin 69 Suppl.: Ann. Orn. 17:75-92.

Schuchmann 1999: HBW vol 5.

Hilty 2002, Guide to the birds of Venezuela.

ZIMMER, J. 1952a. Studies of Peruvian birds, No. 62. The hummingbird genera Patagona, Sappho, Polyonymus, Ramphomicron, Metallura, Chalcostigma, Taphrolesbia and Aglaiocercus. American Museum Novitates 1595: 1-29.

 

Gary Stiles, December 2004

 

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Comments from Remsen: "YES. If A. kingi and A. coelestis are syntopic, then their degree of difference can be applied as a standard by which to rank allopatric taxa."

 

Comments from Pacheco: "YES. O tratamento em duas espécies encontra suporte nos dados agora disponíveis."

 

Comments from Jaramillo: "YES _ The data sound good. I assume we are going with Venezuelan Sylph as an English name? Or does this require a second proposal pending the outcome of this one?"

 

Comments from Nores: "SI. La gran diferencia de color en la hembra y algunas diferencias en el macho parecen ser suficientes para considerarlas especie diferentes."

NOTA: pienso que, en todas las propuestas sobre colibríes, excepto la 144, las características de coloración y distribución geográfica corresponden mejor a subespecies que a especies. Aunque tampoco nosotros tenemos fundamento de peso para afirmar esto, considero que sería importante no tener en cuenta los cambios introducidos en el HBW hasta tanto haya estudios genéticos, de vocalizaciones u otros que justifiquen la separación de las especies."