Proposal (611) to South American Classification Committee

Merge Ocyalus and Clypicterus with Cacicus

The paper of Alexis F.L.A. Powell, F. Keith Barker, Scott M. Lanyon, Kevin J. Burns, John Klicka, Irby J. Lovette (2014) A comprehensive species-level molecular phylogeny of the New World blackbirds (Icteridae) Molecular Phylogenetics and Evolution, doi: http://dx.doi.org/10.1016/j.ympev.2013.11.009 offers radically new insights into the phylogeny of all four subfamilies included in the Icteridae: Sturnellinae: Meadowlarks; Cacicinae: Caciques and Oropendolas; Icterinae: Orioles; Agelaiinae: Blackbirds, Cowbirds and Grackles. To quote from their abstract:

“Using mitochondrial gene sequences from all ~108 currently recognized species 7 and six additional distinct lineages, together with strategic sampling of four nuclear loci and 8 whole mitochondrial genomes, we were able to resolve most relationships with high confidence. Our phylogeny is consistent with the strongly supported results of past studies, but it also contains many novel inferences of relationship, including unexpected placement of some newly sampled taxa, resolution of relationships among major clades within Icteridae, and resolution of genus-level relationships within the largest of those clades, the grackles and allies.”

The South American Checklist currently assigns Casqued Oropendola (oseryi) to the genus Clypicterus Bonaparte, 1850, and Band-tailed Oropendola (latirostris) to Ocyalus Waterhouse, 1841. Yet in every one of the 4 trees in Powell et al (2013), these two species are nested within the genus Cacicus Lacépède, 1799.

Figure 1 displays “Phylogeny of the New World blackbirds (Icteridae) inferred from mitochondrial DNA sequences of 118 taxa (outgroups not shown). The topology shown here is the single best tree (-lnL = 112464.25) found under maximum likelihood (ML). Nonparametric bootstrap percentages from ML analysis appear immediately above or below branches. Filled circles indicate nodes with estimated posterior probabilities of 0.95 in Bayesian analyses of the same concatenated dataset.”

In this figure, latirostris forms a sister-clade with Cacicus haemorrhous, and although this clade enjoys only 49% support, the whole clade, consisting of oseryi, haemorrhous and latirostris, has 100% support.

Figure 2 shows: “Phylogeny of the New World blackbirds (Icteridae) inferred from nuclear DNA sequences of 46 taxa (outgroups not shown). The topology shown here is the single best tree 6 (−lnL = 14620.36) found under maximum likelihood (ML). Nonparametric bootstrap percentages from ML analysis appear immediately above or below branches. Filled circles indicate nodes with estimated posterior probabilities of >0.95 in Bayesian analyses of the concatenated dataset, and filled squares indicate nodes that also received posterior probability estimates of >0.95 in species-tree analyses.”

In this figure Ocyalus latirostris forms a sister-clade with Cacicus sclateri with a ML figure of 96%, and square for this clade is filled.

Figure 3 shows: “Phylogeny of the New World blackbirds (Icteridae) inferred from mitochondrial and nuclear DNA sequences of 46 taxa (outgroups not shown). The topology shown here is the single best tree (-lnL = 105577.92) found under maximum likelihood (ML). Nonparametric bootstrap percentages from ML analysis appear immediately above or below branches. Filled circles indicate nodes with estimated posterior probabilities of >0.95 in Bayesian analyses of the concatenated dataset, and filled squares indicate nodes that also received posterior probability estimates of 0.95 in species-tree analyses.”

As in Figure 2, Ocyalus latirostris forms a sister-clade with Cacicus haemorrhous, this time with 98% ML probability, and again the node joining them has a filled square.

Finally Figure 4 displays: “Phylogeny of the New World blackbirds (Icteridae) inferred from mitochondrial and nuclear DNA sequences of 118 taxa (outgroups not shown). The topology shown here is the single best tree (-lnL = 127652.47) found under maximum likelihood (ML). Nonparametric bootstrap percentages from ML analysis appear immediately above or below branches. Filled circles indicate nodes with estimated posterior probabilities of 0.95 in Bayesian analyses of the same concatenated dataset.”

This tree shows Clypicterus oseryi forming a sister-clade to Cacicus haemorrhous, and the junction of these forms a sister-clade with Ocyalus latirostris. Although the junction of oseryi and haemorrhous has only 48% support, the node combining all three taxa has 100% ML support and the node has a filled circle which indicates that it has posterior probabilities of >0.95 in Bayesian analyses of the same concatenated dataset.

Thus the proposal is that Clypicterus oseryi and Ocyalus latirostris become Cacicus oseryi and Cacicus latirostris.

References:

Alexis F.L.A. Powell, F. Keith Barker, Scott M. Lanyon, Kevin J. Burns, John Klicka, Irby J. Lovette (2014) A comprehensive species-level molecular phylogeny of the New World blackbirds (Icteridae) Molecular Phylogenetics and Evolution 71: 94-212.

John M. Penhallurick, December 2013

Comments solicited from Alexis Powell: “The nesting of Clypicterus and Ocyalus within Cacicus is strongly and independently supported by nuclear and mitochondrial loci (Price and Lanyon 2004, Powell et al. 2014). Renaming them to make Cacicus monophyletic seems more reasonable/conservative than the alternative of erecting/resurrecting 3 or more genera for clades of species now placed in Cacicus.”

Comments from Remsen: “YES. The genetic data require this merger … or the fracture of Cacicus into multiple genera, which would be particularly cumbersome because the type species for Cacicus is haemorrhous. Incidentally, the tail pattern of latirostris is very cacique-like. If this passes, we will need a proposal on English names, i.e., to change the two ex-oropendolas to caciques.”

Comments from Stiles: “YES. Given the genetic data, the only alternative would be to split Cacicus into a least four genera, which I find unwieldy to say the least.”

Comments from Pacheco “YES. Sou de opinião que a subordinação desses dois táxons ao gênero Cacicus seja a medida mais apropriada em vista dos resultados de Alexis et al. 2014.”

Comments from Zimmer: “YES. The genetic data dictate a change, and it is either this or we erect/resurrect several additional genera, which nobody seems to want.”

Comments from Jaramillo: “YES - but grudgingly. There must be something else going on here, I can’t believe that the plumage of Clypicterus, is so oropendola like for no reason. I can’t tell you what that reason is now, but it is uncannily an oropendola. I wonder if there is either some ancient transfer of genes that went on here, or perhaps there is some mimicry going on…something weird. I just can’t put my finger on it, but cannot argue against the genetic data as strong as it is.”

Comments from Robbins: “YES. Wow, what surprising results! Yes, to subsuming these two unique taxa into Cacicus, instead of erecting a number of genera.“