Proposal (658) to South American Classification Committee

Resurrect Vireosylva for the eye-lined vireo clade

Effect on SACC: This proposal would 1) transfer Vireo leucophrys, V. philadelphicus, V. olivaceus, V. gracilirostris, V. flavoviridis, and V. altiloquus to the resurrected genus Vireosylva Bonaparte 1838, 2) transfer Vireo sclateri to Vireosylva, provided the SACC proposal to transfer Hylophilus sclateri to Vireo also passes, and 3) change 3 specific epithets (philadelphicus, olivaceus, and altiloquus) to (philadelphica, olivacea, and altiloqua) to agree in gender with Vireosylva.

Background:

The SACC Vireonidae footnotes include the following:

7a. Genetic data (Murray et al. 1994) support the traditional "eye-lined" species group (here including V. leucophrys, V. philadelphicus, V. olivaceus, V. gracilirostris, V. flavoviridis, and V. altiloquus) as a monophyletic unit within the genus Vireo; these species were formerly (e.g., Ridgway 1904) placed in a separate genus, Vireosylva. Slager et al. (2014) confirmed that they formed a monophyletic group, but only if Hylophilus sclateri is included (see Note 12a). SACC proposal badly needed.

8a. Sibley & Monroe (1990) considered Vireo olivaceus and V. flavoviridis to form a superspecies, and V. altiloquus to form a superspecies with Caribbean V. magister; they excluded V. gracilirostris from either superspecies because they thought it might be more closely related to the latter subspecies even though gracilirostris was formerly considered a subspecies of V. olivaceus (see Note 9). Blake (1968) and Mayr & Short (1970) considered V. olivaceus (with flavoviridis and gracilirostris treated as conspecific) to form a superspecies with V. altiloquus and excluded V. magister. Collectively, these taxa form a monophyletic group, but relationships within the group (Slager et al. 2014) do not conform to any of these superspecies designations. SACC proposal needed <wait follow-up taxonomic paper by Slager et al., and NACC>

12a. Slager et al. (2014) found that Hylophilus sclateri was not a member of any of the three lineages currently included in Hylophilus (see Note 11) and that it was a member of the Vireosylva group (see Note 7a). SACC proposal badly needed.

New Information:

Slager et al. (2014) produced a phylogeny of Vireonidae using mitochondrial (ND2) and nuclear (3 Z-linked loci) data that included 221 samples representing 46/52 currently recognized vireonid species. Their Figure 1, Figure 2, and Figure S1 illustrate the deep phylogenetic split between the eye-lined vireo clade and the rest of the vireos.

Analysis:

The well-supported node separating the Vireosylva clade from the rest of Vireo in Slager et al. (2014) is comparable in depth to the node separating Vireo from the Pachysylvia greenlets.

Note:  The extralimital Vireo hypochryseus represents a very ancient lineage that may be sister to Vireo sensu lato or sister to the Pachysylvia greenlets, but its phylogenetic position is rather poorly resolved in Slager et al. (2014).  A taxonomically conservative approach for the NACC would be to list it first in the linear sequence of Vireo, but this does not directly concern SACC.

Recommendation:

I recommend a YES vote. Recognizing Vireosylva would highlight a major phylogenetic division in what is currently a diverse and species-rich genus and make the divergence depth between genera more consistent across Vireonidae. There is also historical precedent (Ridgway 1904, AOU 1931) for recognizing the eye-lined vireo clade in its own genus, Vireosylva.

Literature Cited:

American Ornithologists' Union. 1931. Check-list of North American Birds, 4th edition. American Ornithologists' Union. Lancaster, Pennsylvania.

Ridgway, R. (1904) The Birds of North and Middle America. Bulletin of the United States National Museum, no. 50, pt.3.

Slager, D.L., Battey, C.J., Bryson, R.W. Jr., Voelker, G., & Klicka J. (2014) A multilocus phylogeny of a major New World avian radiation: The Vireonidae. Molecular Phylogenetics and Evolution 80, 95-104.

Dave Slager, November 2014

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Comments from Stiles: “YES. Recognizing Vireosylva seems appropriate given the phylogeny (I have never been entirely content with many of the Shortian superspecies..).”

Comments from Stotz: “NO, weakly. This is a clear split within Vireo, and a deep one. However, this is not a required split, in the sense that Vireo and Vireosylva are sister taxa. Given that we just had to split up the greenlets because Hylophilus was not monophyletic, I am not inclined to split these two units, since Vireo (with the inclusion of sclateri and with the possible exception of hypochryseus) is monophyletic.”

Comments from Nores: “NO, to be consistent with my response to the Proposal 656.”

Comments from Zimmer: “YES. Doug is correct in saying that such a split is not required given that with or without the split (assuming we include sclateri), we would be left with a monophyletic genus. Thus, it comes down to a matter of taste, and I almost always prefer more internally cohesive, narrowly defined genera to larger, more heterogeneous ones.”

Comments from Robbins: “NO to subdividing the genus Vireo. I agree with Doug’s comments. It isn’t necessary as it is a monophyletic clade and by not changing it there is some stability.”

Comments from Remsen: “YES. Vireosylva marks a deep and distinctive (by vireo standards) branch of the family. Restoring Vireosylva (as in Ridgway; also recognized by A. R. Phillips) would make the all nodes uniting what we label as genera roughly the same depth in the tree.”

Comments from Cadena: “NO. For the sake of stability, I think we should only change our classification when strictly necessary, i.e. when existing arrangements imply non-monophyly of taxa above the species level. Because the two clades in question here are sister to each other, there is no need to change.”

Additional comments from Stiles: “I might add that it would be highly desirable to sequence V. masteri because it is the only member of the genus to combine the eyeline and distinct wing-bars, and its position might be enlightening in this respect. The type is in ICN, but it might be better to extract a toepad from the paratype (in the Instituto Humboldt collection), as it is already partly destroyed but does, as I recall, have both feet!”

Comments from Areta: “NO. This is a difficult decision, and I have been moving back and forth between the trees, the proposal, and the morphological/vocal aspects of all these birds. I agree in that the split is fairly deep and it generally seems to be a matter of taste on whether leaving all in Vireo or choosing to separate a group of birds in Vireosylva. I favor cohesive genera instead of large meaningless groupings, so I would favor this split even if it was not "mandatory" to avoid lack of "monophyly".

“Taxon and geographic sampling of Slager's paper is terrific. However, 33% (two out of six) Vireo breeding in the SACC zone have not been sampled. Phylogenetic positions of both unsampled species (V. gracilirostris and V. masteri) are discussed by Slager et al. (2014). It is very likely that V. gracilirostris pertains to Vireosylva based on song, biogeography and plumage. However, placement of V. masteri is more doubtful. Although Salaman & Stiles (1996) suspected it was more closely related to V. carmioli and indicated that it belonged to the subgenus Vireo, they were very cautious, concluding that "until a more comprehensive genetic analysis of the vireos is performed, including masteri and all possible relatives, we consider it premature to propose sister-group (or super-species) relationships of masteri with any other form". Given the plumage features shown by masteri (bold wing-bars and marked eye-line) and the sometimes surprising phylogenetic position of vireonids uncovered by Slager et al. (2014), I would not know what to do with this species’ generic placement other than speculating without a solid foundation. Because Vireo itself is monophyletic, it won't harm to wait until the position of masteri is solved using the same molecular phylogenetic methods.

“I appreciate the "Unsampled taxa" section in Slager et al. (2014). All phylogenetic papers should have this, which honestly clarifies what is missing in terms of sampling (at least at the species level).”