Proposal (137) to South American Classification Committee

Recognize Thalurania hypochlora as a species distinct from T. colombica (or fannyi)

Hypochlora was described as a separate species by Gould (1870) and so recognized by Cory (1918), as were various forms now considered races of T. furcata of eastern South America that have been shown to intergrade at various points despite sometimes pronounced color differences in males. It differs from other trans-Andean forms of the genus in that the males have a green, rather than violet, abdomen and is geographically isolated in SW Ecuador and NW Peru from other races, which extend S to NW Ecuador W of the Andes. Peters (1945) lumped all cis- and trans-Andean forms of this complex into T. furcata without comment, a treatment followed by Zimmer (1950) and Meyer de Schauensee (1966) as well as Wetmore (1965), who noted that it might be better to split the glittering-crowned trans-Andean forms from the (mostly) dull-crowned furcata group of E of the Andes. The AOU (1983) split the glittering-crowned trans-Andean forms as T. colombica, considering this to be a member (with furcata) of a superspecies, as suggested by Wetmore, and this was followed by Sibley & Monroe (1990) and Hilty & Brown (1986). Finally, Escalante & Peterson (1992) split T. fannyi from colombica based exclusively on crown color of males (green vs. purple), and this treatment was followed by Schuchmann (1999) in HBW. In no analysis were females considered in detail.

Finally, Ridgely & Greenfield (2001) split hypochlora as a separate species from fannyi based on its green abdomen in males, uniform grey underparts in females (those of fannyi being described as bicolored, pale grey anteriorly and dark grey posteriorly) and isolated distribution.

Several things seem worth noting regarding this complex: first, the violet coloring above and depth of tail fork in males decrease and the bronzy color of the nape increases S along the Pacific slope of Colombia into N Ecuador, and the bicolored nature of the female underparts decreases until in SW Colombia and NW Ecuador their underparts are nearly uniform, approaching hypochlora. In all of these forms, females have a blue shoulder, this tendency accentuating southward and being most pronounced in hypochlora. In these features, hypochlora seems to represent the endpoint of trends present in other forms along the Pacific slope (N to S, fannyi-subtropicalis-verticeps). Only in the abdomen of males is a distinct jump seen, perhaps not surprising given the gap in ranges, and I am somewhat hesitant to make a split based solely on this feature, given the degree of variation in male plumages throughout this complex and the frequent intergradation of different-looking cis-Andean forms. My tentative recommendation is to maintain hypochlora as a race of fannyi/colombica pending more thorough analyses. (I might mention that birds intermediate in crown color between colombica and fannyi have recently been taken in NW Colombia and that female plumages do not justify splitting these forms, but I will present these data later when I get them written up, hence will make no recommendation on this point here). For the present, I recommend (tentatively) a NO vote on this proposal. 

Literature Cited: 

Gould 1870, PZSL.

Cory 1918, Catalogue of Birds of the Americas, Part II no. 1.

Peters 1945, Checklist of Birds of the World, vol. 5

ZIMMER, J. 1950d. Studies of Peruvian birds, No. 58. The genera Chlorostilbon, Thalurania, Hylocharis, and Chrysuronia. American Museum Novitates 1474: 1-31.

Wetmore 1965, Birds of the Republic of Panamá, vol. 2

Meyer de Schauensee 1966, The Species of Birds of South America

AOU 1983, Checklist of North American Birds, sixth edition

ESCALANTE-PLIEGO, P., AND A. T. PETERSON. 1992. Geographic variation and species limits in Middle American woodnymphs (Thalurania). Wilson Bull. 104: 205-219.

Sibley & Monroe 1990, Distribution and Taxonomy of Birds of the World

Ridgely & Greenfield 2001, Birds of Ecuador

Gary Stiles, November 2004

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Comments from Remsen: "NO. Additional data must be published to justify this split."

Comments from Pacheco: "NO. Da minha parte, eu prefiro apoiar o arranjo corroborado por Valdéz-Velásquez (2003) para este caso, no qual o táxon hypochlora subordina-se subespecificamente à Thalurania fannyi. Portanto: Thalurania fannyi hypochlora.

Source: Valdés-Velásquez, A. (2003) Taxonomy, phylogeny, and biogeography of the Hummingbird Genus Thalurania Gould, 1848 (Aves: Trochilidae). Universität Bonn. Thesis. Disponible on <http://hss.ulb.uni-bonn.de:90/ulb_bonn/diss_online/math_nat_fak/2003/2003.htm>http://hss.ulb.uni-bonn.de:90/ulb_bonn/diss_online/math_nat_fak/2003/2003.htm 

Comments from Jaramillo: "NO. Thanks for the reference to Valdés-Velásquez, which corroborates Gary's take on the hypochlora issue."

Comments from Nores: "NO; pienso que el razonamiento de Stiles, especialmente la variación gradual de algunos caracteres de norte a sur, es apropiado para tratar esta propuesta. No obstante, las razones para separar colombica y fannyi de furcata no son mucho más definidas que en este caso. Hasta que no haya un análisis genético de todo el grupo, la separación de las subespecies en especies o la unión de las subespecies en una sola especie, es arbitrario."