Proposal (886) to South American Classification Committee

Resurrect Philodice as a separate genus from Calliphlox

Effect on the South American Checklist: This proposal would move Purple-throated Woodstar and the extralimital Magenta-throated Woodstar, currently placed in the genus Calliphlox, to the resurrected genus Philodice.

Background: This proposal is submitted to revisit the issue of splitting Philodice from Calliphlox, the subject of SACC 164 in February 2005 (https://www.museum.lsu.edu/~Remsen/SACCprop164.htm). The submitter (F. G. Stiles) recommended against the split and the proposal did not pass. However, there are now compelling phylogenetic studies published subsequently to the consideration of that proposal over fifteen years ago.

The taxonomic history of these taxa and their inclusion in either Philodice or Calliphlox over the years is well discussed by Gary Stiles in the earlier proposal and will not be repeated in detail here. Suffice it to say that the 2006 proposal was rejected because the Committee felt that there were insufficient morphological differences between Philodice and Calliphlox to support generic separation.

Instead, this proposal will summarize new information available from recent robust phylogenetic studies that require the transfer of Purple-throated Woodstar Calliphlox mitchellii (and the extralimital Magenta-throated Woodstar Calliphlox bryantae) to Philodice. A separate proposal is being submitted simultaneously to NACC on this same issue.

New Information: In recent years the family Trochilidae has been the subject of several robust phylogenetic studies. Two of these are specifically relevant to the present proposal. McGuire et al. (2014) examined the entire family and produced a time-calibrated phylogram based on a sampling of 284 hummingbird species representing 101 of the 105 then-recognized genera using four nuclear and two mitochondrial genes. This resulted in the a more detailed reconfirmation of the eight major clades within the family, one of which was composed of the woodstars, sheartails, Selasphorus, and relatives and which corresponds to the tribe Mellisugini (or the “bees”) (McGuire et al. 2007). Licona-Vera & Ornelas (2017) produced a dated multilocus phylogeny of the Mellisugini based on a dense sampling of 116 individuals from all 16 recognized genera within the tribe and 32 of the 36 extant species using two mitochondrial and four nuclear genes. Their phylogeny of Mellisugini had a similar topology to that of McGuire et al. (2014).

The significant portions of both phylogenies are illustrated below:

McGuire et al. 2014

Licona-Vera & Ornelas (2017)

Both phylogenies demonstrate that Calliphlox, as has been recently treated by the SACC (and NACC), is polyphyletic. Of its five species, the two Bahama endemics, Calliphlox evelynae and C. lyrura, belong to a completely different subclade (“Caribbean Sheartails”) from the other three which are in the traditional “woodstar” clade. The NACC recently dealt with this issue by resurrecting the genus Nesophlox Ridgway, 1910, for the two Bahamian taxa (NACC 2019-D-14).

To date, both committees have retained the three other species in Calliphlox. However, although these three species belong to the same subclade, Amethyst Woodstar Calliphlox amethystina, the type species for Calliphlox, is a basal taxon to the entire “woodstar” clade and is phylogenetically widely separated from the two others, Magenta-throated Woodstar Calliphlox bryantae and Purple-throated Woodstar Calliphlox mitchellii, which are sister species. These latter two species form a discrete subclade in themselves which is phylogenetically closer to members of three other genera (Eulidia, Microstilbon, Chaetocercus) than it is to the basal Calliphlox amethystina.

Despite what may have been considered only minor morphological differences in the initial SACC proposal, these phylogenetic findings require that Calliphlox bryantae and Calliphlox mitchellii must be treated in a separate genus from C. amethystina, for which the genus Philodice Mulsant, Verreaux, J & Verreaux, E, 1866 (Type Trochilus mitchellii Bourcier) is the appropriate available name and should be resurrected. A complementary proposal on this issue is being submitted to NACC simultaneously.

We strongly recommend a YES vote to Part A of this proposal, to resurrect Philodice.

Should the proposal pass, we also strongly recommend (B) continuing to use the group name “woodstar” for all. Most members of this clade, which is comprised of several genera, have long been called woodstars, so this would not affect stability.

Please vote on both A and B.

References:

Licona-Vera, Y. & J.F. Ornelas. 2017. The conquering of North America: dated phylogenetic and biogeographic inference of migratory behavior in bee hummingbirds. BMC Evolutionary Biology 17:126.

McGuire, J.A., C.C. Witt, D.L. Altshuler & J.V. Remsen. 2007. Phylogenetic Systematics and Biogeography of Hummingbirds: Bayesian and Maximum Likelihood Analyses of Partitioned Data and Selection of an Appropriate Partitioning Strategy. Syst. Biol. 56(5):837–856.

McGuire, J.A., C.C. Witt, J.V. Remsen, A. Corl, D.L. Rabosky, D.L. Altshuler & R. Dudley. 2014. Molecular phylogenetics and the diversification of hummingbirds. Current Biology 24(8): 910–916.

Remsen, J.V. 2019. NACC Proposal 2019-D-14. “Reinstate Nesophlox for Calliphlox evelynae and C. lyrura”. In: American Ornithological Society. Checklist of North and Middle American Birds. http://checklist.americanornithology.org/nacc/proposals/2019.html

Stiles, G. 2005. SACC Proposal 164. “Recognize Philodice as a separate genus from Calliphlox” In: Remsen, J.V. et al. A classification of the bird species of South America. American Ornithological Society. http://www.museum.lsu.edu/~Remsen/SACCBaseline.htm

David B. Donsker, Pamela C. Rasmussen, Nicholas A. Mason, September 2020.

Comments from Areta: “A. YES, mitchellii and bryantae cannot be kept in Calliphlox and moving them to Philodice is a reasonable option. The divergence times among genera in the South American clades seem relatively recent in comparison to those of other genera in the bee clade, so perhaps in the future the limits of Chaetocercus/Microstilbon/Eulidia/Philodice, Thaumastura/Myrmia, and Rhodopis/Myrtis, etc. may need to be revisited.

“B. YES to keeping woodstar for Philodice.”

Comments from Robbins: “There is no question that mitchellii and bryantae need to be removed from Calliphlox’ however, what genus should they be moved to is open to question. Why? Looking at just those portions of the hummingbird phylogenies presented in this proposal, if one applies a consistent treatment based on branch lengths (with reference to Archilochus, Doricha, and Calothorax), then one could argue that Chaetocercus, Microstilbon, Eulidia could be merged into a single genus (not sure which would have priority). Mitchellii and bryantae would be placed in that genus. Ditto for placing Rhodopis, Myrtis, Thaumastura and Myrmia into a single genus. Instead of doing this piecemeal, why not address these issues now?”

Comments from Zimmer: “I’m all for removing mitchellii and bryantae from Calliphlox, the need for which is made clear by the two phylogenies presented. But, as stated by Mark, and as suggested by Nacho, the branch lengths for several of the species/genera in the clade suggest that these “bee hummingbirds” may be overly split at the generic level, and that mitchellii and bryantae might be better treated in a single genus along with Chaetocercus, Microstilbon, and Eulidia, rather than by themselves in a resurrected Philodice. So, I would hold off on resurrecting Philodice, until the larger issue can be resolved, with the explicit understanding that mitchellii and bryantae must be removed from Calliphlox. As a matter of housekeeping, I’m not sure how this works. Do I need to vote “NO” and then wait for a new, expanded proposal, or can we break #886 into a Part A (remove mitchellii and bryantae from Calliphlox – “YES” for me on that) and a Part B (place them in a resurrected Philodice – “NO” for me on that)?”

Comments from Stiles: “YES. I have long been aware of this separation but had  not mentioned it because I am (still) trying to decide what to do with its near relatives for a coherent revision of the woodstars! (we might discuss this later).”

Comments from Jaramillo: “A. YES. Philodice is notable for their longer tails among other differences. B. YES.”

Comments from Pacheco: “YES. In favor of removing mitchellii and bryantae taxa from Calliphlox.”

Additional comments from David Donsker: “We know, and all agree, that retaining mitchellii and bryantae in Calliphlox is taxonomically and phylogenetically incorrect. It’s simply untenable to retain them in this genus based on the phylogenetic analyses available to us. It is true, as Mark points out, that these two species are closely related to those in Eulidia, Chaetocercus, and Microstilbon and that they all might be best treated in a single genus. But considering and resolving that treatment may be some considerable and unknown distance off. This seems to be an example of a better solution to the problem suffering for the promise of the best solution to the problem. Even within the clade that contains these two species plus Eulidia, Chaetocercus and Microstilbon,  he two species mitchellii and bryantae form a discrete subclade. They are also morphologically distinctive from the other species within the larger clade. So, arguably, they at least could be justified as a valid “subgenus.” Philodice is nomenclaturally correct as a genus-group name, and is taxonomically justified in that sense for its limited use for these two species. So, its adoption to define this smaller clade would be appropriate, and it has to be better than retaining the two species, knowingly incorrectly, in Calliphlox. I would urge the Committee to accept Philodice, even if it only may be for an undefined time, to correct the unjustified taxonomy as it currently stands.”

Comments from Claramunt: “YES. But I agree with others in that the generic classification of these woodstars is too atomized and would benefit from some merging. I also agree that rejecting this proposal on those grounds would be inappropriate. So, I think we should accept this one but move rapidly to proposing a new classification for this group.”

Comments from Remsen: “A. YES. These two species must be removed from Calliphlox (for now anyway – I also agree that this whole group is oversplit at the genus level due to strong differences in sexually selected male plumage and ornamentation, and the young age of this lineage indicates to me that a major consolidation of genera better reflects their evolutionary history. B. YES – sensible.”