Proposal (724) to South American Classification Committee

 

Merge Cyanocompsa cyanoides and C. brissonii into Cyanoloxia

 

Background: From SACC’s footnotes:

 

“24. Some authors merge Cyanocompsa into Passerina (e.g., Paynter 1970c). Klicka et al. (2000) found that the two genera are sisters. Klicka et al. (2007), with broader taxon sampling, confirmed that they are sisters but that the Cyanocompsa group also included Cyanoloxia and Amaurospiza, and recommended the merger of the three genera (Cyanoloxia has priority).  SACC proposal to expand Cyanoloxia did not pass.  Sibley & Monroe (1990) considered Cyanocompsa brissonii and Middle American C. parellina to form a superspecies.  Klicka et al. (2007), however, showed that they are not sister species.  Bryson et al. (2014) found that C. parellina is actually sister to Passerina and recommended merger of parellina into Passerina.  This leaves Cyanoloxia available for cyanoides, brissonii, and glaucocaerulea, which is desirable because Bryson et al. (2014) also found that Cyanocompsa brissonii and Cyanoloxia glaucocaerulea are sisters.  SACC proposal badly needed.”

 

Analysis: The signal of parellina being closely related to Passerina, although weak in the concatenated analysis of Bryson et al. (2014), is also present in the ND2, FGB5 and ACO1 datasets when analyzed independently (I ran maximum likelihood analyses in RAxML) albeit with only weak bootstrap support. Only the MYC dataset showed parellina in a clade with Amaurospiza and the other Cyanocompsa.  But this gene also shows other anomalies such as Passerina being paraphyletic with regard to all other genera of ‘blue’ cardinals and Spiza.  The multilocus “species tree” analysis in  *BEAST (Bryson et al. 2014) shows parellina at the base of the Passerina clade with PP > 0.95, suggesting that the incongruence of the MYC dataset can be explained as an instance of incomplete lineage sorting.

 

Recommendation: In my opinion, the molecular evidence for parellina being in the Passerina clade instead of with the other “Cyanocompsa” species is moderately strong. Since parellina is the type species of Cyanocompsa, the other species need a different generic name. The only name immediately available for that clade is Cyanoloxia. This leads to option A: merge cyanoides and brissonii into Cyanoloxia.

 

Additionally, now that all species of Amaurospiza have been included in the tree, we may reconsider the proposal of Klicka et al. (2007) of merging Amaurospiza into Cyanoloxia as well. This is would be option B. They are clearly sister groups, so this option is a matter of ranking (the gray zone). Morphologically, there are some size differences between these clades but not much more.  Amaurospiza was included in Emberizidae in the past, instead of in Cardinalidae, but I don’t think that classification was based on anything but the fact that they look superficially like a small sparrow. Amaurospiza species are small and are bamboo specialists.

 

Finally, for the sake completeness, we can consider merging all “blue cardinals” into a single genus, Passerina (i.e. returning to the classification proposed by Paynter 1977 with the addition of Amaurospiza). This is option would be C, and may be justified by the position of parellina, which blurs the gap between the two major subgroups because it looks very like a member of the Cyanoloxia clade but belong into the Passerina clade.

 

I don’t have a strong opinion regarding these three options but I vote for option A because it represents the minimum change necessary.

 

References:

BRYSON, R. W., J. CHAVES, B. T. SMITH, M. J. MILLER, K. WINKER, J. L. PÉREZ-EMÁN, J. & KLICKA. 2014. Diversification across the New World within the ‘blue ‘cardinalids (Aves: Cardinalidae). Journal of Biogeography 41:587-599.

KLICKA, J., K. BURNS, AND G. M. SPELLMAN. 2007. Defining a monophyletic Cardinalini: A molecular perspective. Molecular Phylogenetics and Evolution 45: 1014-1032.

PAYNTER, R. A., JR.  1970. Subfamily Cardinalinae. Pp. 216-245 in "Check-list of birds of the World, Vol. 13" (Paynter R. A., Jr., ed.). Museum of Comparative Zoology, Cambridge, Massachusetts.

 

Santiago Claramunt, October 2016

 

 

Note from Remsen: let’s take Option A as a stand-alone proposal, and then consider the other options subsequently.

 

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Comments from Stiles: “YES to A (and I also think that B is reasonable, but am willing to go along with only A for now).”

 

Comments from Pacheco: “YES to A, because it represents the smallest change necessary, and also because these 3 seem to represent an unambiguous natural group.”

 

Comments from Robbins: “For now, I’ll support moving cyanoides and brissonii into Cyanoloxia; however, I would support placing all the “blue cardinals” into Passerina (option c).”

 

Comments from Zimmer: “YES” to A.  And, the more I think about it, the more I’m inclined to echo Mark in voicing support for placing all of the “blue cardinals” into Passerina.  Normally, when it comes to questions of ranking sister groups, I favor less inclusive, more internally consistent genera.  But in this case, given the genetic data indicating that parellina is closer to the Passerina clade than to the Cyanoloxia clade, I don’t see a place to draw the line that really makes sense.  I think that Amaurospiza, Cyanoloxia and Cyanocompsa, as currently constituted, are all very similar to one another morphologically (including male and female plumage patterns), vocally, and ecologically.  While it is true that the species currently in Amaurospiza are bamboo specialists, bamboo thickets are really just a subset of second growth and forest-edge habitats, which fits the other “blue cardinals”, and, when you think about it, also fits our North American Passerina species, none of which are forest interior birds.  In fact, when it comes to habitat and voice, I think of C. cyanoides as the outlier, being more of an interior forest bird, and having a less bunting-like song.  Morphology and male/female plumage patterns, as well as genetics, however, place it firmly in the Cyanoloxia clade.  But to me, the Amaurospiza seedeaters are morphologically, vocally and behaviorally right in there with all of the other “blue cardinals”.  I see a parallel within the genus Hemitriccus, several species of which are essentially obligate inhabitants of bamboo thickets, but none of which has been separated from that genus on purely ecological grounds.  So, if we need to do this in steps, then “YES” on A, but also giving notice of my vote for C, if and when it follows.”

 

Comments from Areta: “YES. This is the simplest way to correct the names of these blue-cardinals. Regarding Amaurospiza, I think it is informative to keep these species in a separate genus and not to merge them with Cyanoloxia, and likewise I am not a fan of having a huge Passerina.”

 

Comments from Remsen: “YES (to A).  A change is required, and Option A fulfills the minimum requirements.”

 

Comments from Stotz: “YES to Option A.  I am moderately inclined to go all the way and adopt Option C, but for now I vote for Option A.”