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Proposal (928) to South American Classification Committee

 

 

Revise generic limits in the Helianthini: A. Treat Heliodoxa schreibersii in the monotypic genus Ionolaima; B. Subsume Clytolaema into Heliodoxa; and C. Subsume Sternoclyta into Heliodoxa

 

 

The comprehensive phylogeny of the Trochilidae by McGuire et al. (2014) has generated major revisions of generic limits in the family that have already been addressed by SACC.  We (mostly Gary) are in the process of addressing a series of minor revisions with each tribe to bring the SACC classification up to date.

 

This proposal addresses two items with the Helianthini.

 

To put the proposed change in context, an overview of the phylogeny with respect to current generic limits is presented below.

 

 

 

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Clade 1. Includes only the genus Haplophaedia, which clearly merits generic status.

Clade 2. Includes the genera Eriocnemis and Loddigesia. The difficulty is that Loddigesia is embedded within Eriocnemis (i.e., Eriocnemis is paraphyletic with respect to Loddigesia). The only reasonable solution is to include Loddigesia within Eriocnemis- but this produces homonymy of the species name mirabilis. The mirabilis of Loddigesia Bonaparte, 1850, has clear priority over that of Eriocnemis (Meyer de Schauensee, 1967), for which a new species epithet is therefore required (suggestions: colorata or polychromata).  However, to do this would require a separate publication with a replacement name for Eriocnemis mirabilis.  Because it was a major surprise that highly distinctive Loddigesia was found to be embedded in Eriocnemis, It also might be prudent to wait for another analysis and additional samples to confirm this somewhat startling result.  <<check on N in McGuire et al.>>

Clade 3. Includes Lafresnaya, isolated on a long branch and clearly retains generic status.

Clade 4. Includes only Aglaeactis, which is also alone on a long branch and is a valid genus.

Clade 5. Includes two sister genera separated on long branches: Pterophanes and Ensifera, which are strongly differentiated morphologically and also definitely merit generic status.

Clade 6. Includes two subclades separated on long branches: a) Boissonneaua, definitely a separate genus; and b) Urosticte and Ocreatus, on moderately long branches; both are morphologically well characterized, and are best accorded generic rank.

 

Clade 7. Includes two genera: Urochroa and Heliodoxa. Here, the genetic data present several alternatives to express relationships. Urochroa (subclade 7a) is the outlier in this clade, although separated on a very short branch relative to Heliodoxa schreibersii (subclade 7b), which is also an outlier to the remaining species of Heliodoxa, also on a short branch.  The remaining species of Heliodoxa comprise three subclades (7c,d,e) on similar branches. This genetic structure suggests several options: A. Given the short branch separating Urochroa, one option would be to subsume Urochroa Gould, 1856, into Heliodoxa Gould, 1849, thus treating all species in clade 7 as congeneric; B. Recognize Urochroa (subclade 7a) and Heliodoxa (7b,c,d,e) as genera: this is the current treatment, which would preserve stability; C. Recognize H. schreibersii as a separate genus, given that it is also an outlier and separated from Urochroa by a shorter branch than that separating this species from the remainder of Heliodoxa (clades 7c,d,e) in the monotypic genus Ionolaima Reichenbach, 1854. This three-genus option (Urochroa, Ionolaima, Heliodoxa) would seem to best express the degrees of genetic relationships in clade 7; it would require continuing to subsume several monotypic genera (including Agapeta Heine, 1863, for gularis; Lampraster Taczanowski, 1874, for branickii; and Polyplancta Heine, 1863, for aurescens) into Heliodoxa (type species, leadbeateri). It would also require subsuming Clytolaema Gould, 1853, for rubricauda. Finally a fourth option (which would seem the least desirable) would be to recognize all of these latter genera, which would be the most disruptive of stability and the least informative regarding relationships.

 

Clade 8. Includes only the genus Coeligena. The genetic tree indicates that three subclades exist: a) a sexually (nearly) monochromatic clade (coeligena, prunellei, wilsoni); b) a dichromatic clade including only C. torquatus and close relatives; and c) the remainder of the species of the genus, all strongly dichromatic. The genus as a whole is characterized principally by all of its members having a rather long, straight to very slightly recurved bill and moderate (ca. 6-8 g) size. The only logical options are to consider all three subclades as congeneric (the current treatment, which would preserve stability) or to split the genus into its three components, as Coeligena (Lesson 1832), Bourcieria (Bonaparte, 1850) and Diphogena (Gould, 1854) respectively. We tentatively prefer the first option.

 

Here are LSUMNS specimen photos of the group (missing H. xanthogonys), with specimens arranged as in the tree above.

 

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Recommendations: To resolve the problems in Clade 7:

 

A. Resurrect Ionolaima for schreibersii:  One of us (Gary) favors this as best expressing the relationships because schreibersii is on such a long branch, but the other (Van) prefers maintaining a broad Heliodoxa for the sake of stability and because of the short branch length separating it from other Heliodoxa.

 

B. Subsume Clytolaema into Heliodoxa: This is a required change if broadly defined Heliodoxa is maintained.  Clytolaema is sister to H. aurescens, with strong support for that node.  To retain Clytolaema would require resurrection of Agapeta and Lampraster, as well as Polyplancta based on branch lengths.  Note that Heliodoxa is not a particularly tight group in terms of morphology and plumage, and so such a subdivision might be justifiable on morphological grounds, but for now, both of us favor including Clytolaema in Heliodoxa.

 

C. Subsume Sternoclyta into Heliodoxa: No tissue of this monotypic genus was available to McGuire et al., but morphologically it is widely regarded as part of this group.  The female plumage is virtually identical to that of H. leadbeateri (the type species of Heliodoxa) and differs only in its more curved bill.  The male plumage is not radically different from some Heliodoxa (especially schreibersii).  Points in favor of a merger are that (1) bill curvature is clearly a plastic character that should not define a genus, (2) sexual selection on male plumage makes male plumage characters potentially misleading, and female plumage may be a better indicator; and (3) even so, male plumage of Sternoclyta is not an outlier in the group.  Points against the merger are: (1) better to wait for genetic data before a merger of genera, and (2) it is possibile that Sternoclyta might be sister to schreibersii, and so if Part A above passes, placing Sternoclyta in Heliodoxa would be incorrect. We recommend erring on the conservative side and maintaining Sternoclyta until genetic data are available.

 

 

Gary Stiles and Van Remsen, November 2021

 

 

 

 

Comments from Areta:

“A. NO. I prefer to retain it in Heliodoxa. Although it might be a deep branch, Heliodoxa is already including relatively deep divergences and using this monotypic genus seems disruptive of stability, and I don´t see any strong phenotypic arguments to reinstate Ionolaima for schreibersii.

 

“B. YES. I prefer to merge Clytolaema into Heliodoxa instead of splitting Heliodoxa in more genera. Unless someone can argue which features would justify separating them in distinct genera, I find the idea of a broad Heliodoxa to be compelling.

 

“C. NO.  Retain Sternoclyta for the time being.  We´ve seen enough surprises in the phylogenetic relationships of hummingbirds and it would be tame to put cyanopectus in Heliodoxa without hard data.”

 

Comments from Robbins:

“A. NO. I agree with Nacho. No need to create yet more genera given the genetic divergence within Heliodoxa.

 

“B. YES to merging Clytolaema into Heliodoxa.

 

“C. YES for subsuming Sternoclyta into Heliodoxa based on the morphological characters pointed out in support of this in the proposal.  Moreover, even if Sternoclyta is sister to schreibersii, given how I voted in part A of this proposal it would still result in placing this taxon in Heliodoxa.”

 

Comments from Lane:

“A) NO. I agree with Van that it is preferable to maintain Heliodoxa for now, especially with the unknown placement of Sternoclyta at this time.

 

“B) YES. This makes sense, and I think has been long expected.

 

“C) NO. Would rather wait for the genetic work to be done before acting on this.”

 

Comments from Pacheco:

 

“A – NO. Agreeing with Van it is preferable to keep keeping schreibersii under Heliodoxa for the reasons presented.

 

“B – YES. A subordination of Clytolaema in Heliodoxa is quite desirable.

 

“C – NO. If this genus Sternoclyta was not sampled by McGuire et al. (2014) it is preferable to keep a combination Sternoclyta cyanopectus until a phylogeny is available.”

 

Comments from Claramunt:

“A. NO to resurrect Ionolaima for schreibersii. It would be an unnecessary disruption of stability and to resurrect a monotypic genus.

 

“B. YES, subsume Clytolaema into Heliodoxa. A change is required and the phenotype of rubricauda seems to fit well in the diversity of Heliodoxa.”

 

“C. NO to subsume Sternoclyta into Heliodoxa. We should wait for actual evidence of relationships to consider this change.”

 

Comments from Bonaccorso:

“A. NO. For now, I would rather maintain taxonomic stability in this case.

“B. YES. It makes sense to subsume Clytolaema into Heliodoxa (it is well within Heliodoxa).

“C. NO until genetic data are available.”

 

Comments from Zimmer:

A.  NO.  Like Van, I would prefer maintaining a broad Heliodoxa, especially considering the short branch lengths involved, and, from a phenotypic standpoint, I think schreibersii still fits nicely within Heliodoxa as currently defined.

B.  YES, Clytolaema is pretty clearly embedded within Heliodoxa, and the only alternative to making this change would be hairsplitting current Heliodoxa into more genera, which would result in a treatment that would be both destabilizing and uninformative in my opinion.

C.  NO, despite the morphological similarities alluded to in the Proposal, I think it is best to wait until we have some actual genetic data to hang our hats on before making this change.

 

Additional comments from Stiles:

“A. NO. I'll switch to NO for placing it in a separate genus (based on unpublished genetic data.)