Resurrect Sporagra for South American goldfinches and siskins
Effect on SACC: This would change the genus name from Carduelis to Spinus for all South American species in that genus (but would retain Carduelis for introduced C. carduelis and resurrect Chloris for introduced C. chloris).
Background: These species were all in the proposed genera until Howell et al. (1968) and Mayr & Short (1970) lumped them all in one massive Carduelis with no explicit rationale, much less analysis or data. SACC and everyone else followed that classification.
New information: Arnaiz-Villena et al. (2007) sequenced 940 bp of cyt-B and found that broad Carduelis was polyphyletic. My screen grab of their complete tree is too fuzzy to be readable, so let me now if you need a pdf. Here is part of it (maximum likelihood):
The North American Classification Committee (Chesser et al. 2009) voted to restore the pre-Peters generic classification based on those data; although NACC clearly recognized that such a single-locus study has potential problems, the committee largely agreed that those new data were at least sufficient to return to the previous classification, e.g. Spinus for our goldfinches and siskins and Chloris for the greenfinches, with Carduelis remaining for C. carduelis. There’s no point in repeating all the details of the NACC proposal – you can access it the NACC proposal website. Note that the Neotropical taxa are in a different group from the primarily North American goldfinches (including psaltria).
Then, Nguembock et al. (2009) sampled 5 genes (including one nuclear, two nuclear introns, and two mitochondrial) to examine relationships of carduelines. Although their taxon-sampling was weaker for the New World than that of the previous study, their gene-sampling was much stronger. Broadly, they found similar results (e.g., only C. carduelis retained in Carduelis, Chloris for chloris) except that Spinus was also paraphyletic with respect to true Serinus and Loxia. [Arnaiz-Villena et al. (2007) did not sample much beyond the goldfinch-siskin group, and so their analysis would not have been able to reveal this.] Nguembock et al.’s results are below (Bayesian analysis, majority rule consensus tree, concatenated data); their analyses of single genes such as ND2 did not show the paraphyly of Spinus.
Here’s what our current Note says:
3. New World members of the genus Carduelis were formerly (e.g., Hellmayr 1938, Phelps & Phelps 1950a, Meyer de Schauensee 1966, 1970) placed in the genus Spinus, but recent authors (e.g., AOU 1983, 1998, Ridgely & Tudor 1989) have followed Howell et al. (1968) in merging Spinus into Carduelis. <check Ackermann J. Orn. 108: 430-473, 1967>. Recent genetic data (Arnaiz-Villena et al. 2007, Nguembock et al. 2009) found that Carduelis as currently constituted is not monophyletic and that resurrection of Spinus is required, and Chesser et al. (2009) followed this by placing all New World goldfinches and siskins in Carduelis. Arnaiz-Villena et al. (2007) also showed that the Neotropical species of Carduelis likely form a monophyletic group that might not include C. psaltria, which forms a strongly supported group with the two North American goldfinches, C. tristis and C. lawrencei. Nguembock et al. (2009) found that C. psaltria was sister to the Neotropical group (but did not sample C. tristis or C. lawrencei); they also found that Spinus was more closely related to Loxia than to the New World goldfinch-siskin group, and that the latter was more closely related to true Serinus (at least in their concatenated data set). Therefore, they recommended that Sporagra Reichenbach, 1850, be resurrected for this group.
Nguembock et al.’s (2009) recommendation to recognize Sporagra was “temporary,” evidently because of missing taxa in the New World.
Recommendation: Although the data from the new analyses are not ideal, they are clearly superior to the data-less classification used previously. Minimally, we should follow NACC by resurrecting Spinus for the New World group. However, Nguembock et al. (2009) was not available to Chesser et al. (2009), and I think the data are sufficient for going one step further by resurrecting Sporagra for the South American taxa, including psaltria. Sporagra would presumably also include North American tristis and lawrencei, which were found to form a group with psaltria by Arnaiz-Villena et al. but with no real support, as well as any the South American endemics not sampled by one or both studies. Therefore, I recommend (YES vote) we use Sporagra for all species on our list except the two introduced species, Chloris chloris and Carduelis carduelis (and Spinus would by implication be restricted to spinus, pinus, atriceps, and dominicensis on the NACC list). A NO vote would be to retreat to broadly defined Spinus (or even Carduelis) until more data are available.
Note on English names: If this proposal passes, then the names “goldfinch” and “siskin” not longer have any phylogenetic significance. Rather than tweak the names to reflect generic boundaries (difficult with the only “true” goldfinch being “the” goldfinch C. carduelis), I think it’s better for stability to just add goldfinch and siskin to the growing list of names that indicate morphotypes groups rather than phylogenetic groups.
ARNAIZ-VILLENA, A., V. RUIZ-DEL-VALLE, J. MOSCOSO, J. I. SERRANO-VELA, AND J. ZAMORA. 2007. MtDNA phylogeny of North American Carduelis pinus group. Ardeola 54: 1-14.
HOWELL, T.R., R. A. PAYNTER, JR., AND A. L. RAND. 1968. Subfamily Carduelinae. Pp. 207-306 in "Check-list of birds of the World, Vol. 14" (Paynter, R. A., Jr., ed.). Museum Comparative Zoology, Cambridge, Mass.
MAYR, E., AND L. L. SHORT. 1970. Species taxa of North American birds. Publ. Nuttall Orn. Club 9.
NGUEMBOCK, B. J. FJELDSÅ, A. COULOUX, & E. PASQUET. 2009. Molecular phylogeny of Carduelinae (Aves, Passeriformes, Fringillidae) proves polyphyletic origin of the genera Serinus and Carduelis and suggests redeﬁned generic limits. Molecular Phylogenetics and Evolution 51: 169–181.
Van Remsen, June 2011
Comments from Nores: “YES. It is evident in the analyses by Arnaiz-Villena et al. (2007) and Nguembock et al. (2009) that the South American species form a well-separated clade.”
Comments from Stiles: “At least a partial YES. I see no problem with Sporagra for the bulk of the South American species; the possible exception is psaltria. The A&V study places this species with tristis and lawrencei in a separate group from Sporagra; the N et al. study places it near Sporagra but the split here looks to be deep: the branch lengths between psaltria and the Sporagra group are much longer than those between Spinus, Acanthis, and Loxia, maintained as separate genera in this study (justifiably, in my opinion: Loxia in particular is highly distinctive). To be consistent with this, and assuming that more genetic data will support the close relationship of psaltria, tristis and lawrencei - as seems likely given the good agreement between the two studies in other aspects - it might be best to separate the latter three species from Sporagra, as N et al. do for psaltria (they didn´t sample tristis and lawrencei). They placed psaltria in Pseudomitris (type species psaltria). However, if these three species are indeed congeneric, as the A&V study strongly suggests, Pseudomitris Cassin 1865 should be regarded as a synonym of Astragalinus Cabanis 1851 (type species tristis). Given the combined results of the two studies, I suggest that the best course would be to use Sporagra Reichenbach 1850 for all of the South American (exclusively Neotropical) species and Astragalinus for psaltria, tristis and lawrencei, which are North American (only psaltria also occurs widely in the Neotropics as well but is probably of northern origin where it is more racially and morphologically diverse; only a single subspecies occurs in South America and southern Middle America).:
Comments from Remsen: “Given Gary’s comments above, let’s change the proposal to exclude psaltria – that one is more appropriate for NACC to decide anyway.”
Comments from Pacheco: “YES, com as necessárias alterações sugeridas por Stiles.”
Comments from Zimmer: “YES for resurrecting Sporagra for all of the exclusively South American species of siskins & goldfinches. I would agree with not messing with the English names of “siskin” and “goldfinch”, recognizing that those names reflect morphotypes and not phylogenetic groups.”
Comments from Robbins: “YES. I agree with Gary’s comments concerning not including psaltria within Sporagra. Otherwise, it seems straightforward in placing the remaining Neotropical “siskins” within Sporagra, if indeed that is the oldest name available.”