Proposal (520) to South American Classification Committee

Recognize Aulacorhynchus [d.] whitelianus as a valid species distinct from A. derbianus

Effect on SACC: This change would split an existing species, Aulacorhynchus derbianus, into two species: A. derbianus and A. whitelianus.

Background:

In a phylogenetic analysis of the genus Aulacorhynchus based on two mitochondrial and two nuclear genes, Bonaccorso et al. (2011) concluded that Andean populations of A. derbianus (A. d. derbianus) were more closely related to A. sulcatus, than to populations of A. derbianus from the Guiana Shield (A. d. whitelianus, A. d. osgoodi, and A. d. duidae). Based on these results, the authors proposed that populations of A. derbianus from the Guiana Shield should be treated as a separate species rank, A. whitelianus.

The current SACC note is as follows:

“3a. The whitelianus subspecies group of the Tepui region was formerly (e.g., Cory 1919) considered a separate species from Aulacorhynchus derbianus, but they were treated as conspecific by Peters (1948). Genetic data (Bonaccorso et al. 2011), however, indicate that Andean derbianus is more closely related to A. sulcatus than either is to the whitelianus group. SACC proposal needed to elevate whitelianus group to species rank.”

Analysis and Recommendation:

Given the phylogenetic results presented in Bonaccorso et al. (2011), recognition of Aulacorhynchus whitelianus as a valid species would make taxonomy of genus Aulacorhynchus consistent with evolutionary history. This phylogeny was strongly supported, and the branch conducting to A. whitelianus was sufficiently long (compared to others in the phylogeny) to assure its continuous divergence in isolation; this deep divergence was seen in analyses of both mitochondrial and nuclear genes.

In addition, A. whitelianus and A. derbianus are diagnosable on the base of plumage differences, as well as size (Short & Horne 2002). Finally, from the biogeographic point of view, this split makes perfect sense, by separating the Pantepui endemic from the Andean (A. derbianus) and Andean-Coastal (A. sulcatus) species.

Because of these reasons, I strongly recommend elevating A. whitelianus to species rank.

Cory (1919) used Whitely’s Toucanet as the English name.

References:

Bonaccorso, E., J. M. Guayasamin, A. T. Peterson, and A. G. Navarro-Sigüenza. 2011. Molecular phylogeny and systematics of Neotropical toucanets in the genus Aulacorhynchus (Aves, Ramphastidae). Zoologica Scripta 40: 336–349.

Cory, C. B. (1919). Catalogue of Birds of the Americas and the Adjacent Islands in Field Museum of Natural History. Part 2, No. 2. Chicago: Field Museum of Natural History.

Peters, J. L. (1948). Check-List of Birds of the World, Vol. 6. Cambridge, Massachusetts: Harvard University Press.

Short, L. L. & Horne, J. F. M. (2002). Family Ramphastidae (Toucans). In J. A. del Hoyo, A. Elliot & J. Sargatal (Eds.). Handbook of the Birds of the World. Vol. 7. Jacamars to Woodpeckers (pp. 220–272). Barcelona: Lynx Edicions.

Elisa Bonaccorso, March 2012

Comments from Nores: “YES. The genetic data are convincing for a basal split between the Andean, the Tepuis and the Coastal birds. Clearly whitelianus falls outside of derbianus. However, biogeographic issues alone are not sufficient evidence for considering them different species and could go with either treatment. In addition, allopatric distribution is more typical of subspecies than species.”

Comments from Stiles: “YES. Genetic and morphological evidence both favor this change, and it makes perfect sense biogeographically. Regarding English names, I might suggest “Tepui Toucanet” as a catchier and more evocative moniker for this species.”

Comments from Pacheco: “YES. Os resultados da análise filogenética feita por Bonaccorso et al. corroboram a medida.”

Comments from Robbins: “YES. I agree with Gary’s suggestion of calling it “Tepui Toucanet”.

Comments from Jaramillo: “YES – and I too prefer Tepui Toucanet.”

Comments from Stotz: “NO, because the proposal doesn’t provide any real evidence for what the appropriate treatment of these three taxa is. It does suggest that whitelianus is a subspecies of derbianus, whereas sulcatus retains species status; the current treatment, is hard to maintain. But Manuel asks a fair question. Why not lump all three taxa?”

Comments from Zimmer: “YES”. Given its geographic distribution, which is highly disjunct from that of derbianus, the genetic and morphologic divergence of the whitelianus subspecies group is only going to continue. This is a group on an independent evolutionary trajectory at this point. And yes, it does make biogeographic sense. This treatment, for which there is published supporting data, overturns yet another unsupported Peters (1948) lump. In the event that this proposal passes, I would add my vote to all of those calling for the English name of “Tepui Toucanet” for the whitelianus group. That is the name that sprang immediately to my mind upon reading the name “Whitely’s Toucanet” in the Proposal.”