Proposal (544) to South American Classification Committee

 

Recognize newly described Heliangelus splendidus

 

Effect on South American CL: This would split an existing species on the list (Heliangelus viola) into two species, H. viola and H. splendidus.

 

Background: The Violet-throated Sunangel (Heliangelus viola) is distributed from central Ecuador to northern Peru.  Until recently the species has been considered as monotypic.

 

New Information: Weller (2011) considered that variation in morphological characters of the H. viola has been mostly overlooked by Zimmer (1951) and previous taxonomic researchers as well as recent workers.  Consequently, he undertook a review of its geographic and age-related variation comparing immature, subadult, and adult stages of study specimens, and discussed the taxonomic status.  Weller examined 121 specimens (79 males, 42 females) and concluded that his study revealed three discrete populations in terms of plumage.  These differences refer both to the subspecies and species level.  Thus, Weller described the species H. splendidus with an additional subspecies, H. splendidus pyropus; their ranges are northern Peru and central Ecuador to northwestern Peru (Piura), respectively.  The English name proposed is Brilliant Sunangel.  Weller (2011) also considered his ranking of splendidus as a separate species from viola justified “due to indication of overlapping ranges of H. splendidus spec. nov. and H. viola in northeastern Peru.”  This treatment will make H. viola endemic to Peru.

 

The differences between H. splendidus and H. viola are as follows, from Weller’s diagnosis of splendidus:

 

Diagnosis. Basic plumage (e.g., belly) less deep bronzish than in H. viola (cf. Fig. 2A); frontlet and breast more bluish-green, with the latter on average more extended to the belly (males); gorget patch rather purplish, in females enlarged and broadened towards the breast; fringes of undertail coverts darker, more cinnamon instead of cinnamon-buffish; outer rectrices (i.e., r5) in males longer.”

 

Although these differences seem subtle, in the Discussion, Weller also stated:

 

“Particularly, the plumage differences in adult females of H. viola and H. splendidus spec. nov. are striking and, as this morphological feature is generally considered a conservative character, supportive of the validity of the new taxon. Moreover, distinctness at species level is justified when comparing the current species limits in Heliangelus”

 

Evidence for species rank rests on sympatry at two localities:

 

“Interestingly, parapatric contact between both taxa is indicated in the MaraĖon valley (Celendín) as well as along the upper Utcubamba valley (Levanto; cf. Appendix). If these records are not regarded as vagrants (at least questionable in the case of Levanto, with two specimens of H. s. splendidus subspec. nov. collected within the peripherical [sic] range of H. viola), this overlap may be only of recent origin, being founded in the species’ biogeographic history.”

 

Recommendation:  If the new taxon is sympatric with viola as Weller noted, then splendidus has to be ranked as a separate species.  However, Weller also noted that the species is “partially migratory”, so whether this sympatry represents true sympatry is uncertain.  Therefore, I have no specific recommendation on the proposal.

 

References:

Zimmer, J. T.  1951.  Studies of Peruvian birds.  No. 61.  The genera Aglaeactis, Lafresnaya, Pterophanes, Boissonneaua, Heliangelus, Eriocnemis, Haplophaedia, Ocreatus, and Lesbia.  American Museum Novitates no. 1540: 1-55.

Weller, A.-A.  2011.  Geographic and age-related variation in the Violet-throated Sunangel (Heliangelus viola, Trochilidae): evidence for a new species and subspecies.  Ornitología Neotropical 22: 601-614.

 

Manuel A. Plenge, September 2012

 

 

Comments from Gary Graves: “The characters supposedly discriminating Heliangelus viola from “Heliangelus splendidus” are very subtle.  Is any other pair of species in the coquette clade so morphologically similar?  The degree of differentiation observed among populations of H. viola (as currently recognized) is so slight that it may not warrant recognition at the subspecies level.  This may explain why Zimmer (Studies of Peruvian Birds, No. 61), a champion generator of new subspecies names, could not find any consistent differences between Ecuadorian and Peruvian populations [Zimmer examined specimens from El Tambo, Chugur, Taulis, San Pedro, La Lejia, Leimebamba, Levanto, and Cutervo, as well as 47 additional specimens from Ecuador.  The La Lejia specimens examined by Zimmer are illustrated in panel A of Fig. 2 in Weller’s paper].  Weller’s sample size was larger than Zimmer’s, but his analyses do not convincingly demonstrate that perceived patterns of geographic variation in plumage color in H. viola (as currently recognized) are nonclinal.  The analyses include no spectrophotometric data, regression analyses, or bivariate plots that would shed light on whether the variation is continuous or discontinuous.  Moreover, no genetic data were presented.  New species descriptions do not always require such rigorous quantitative analysis when the distinguishing characters and evidence of sympatry are unequivocal.  But, when a differential diagnosis for a new species hinges on hair-splitting subtleties, such as the degree of bronziness of the ventral plumage or whether the tips of undertail coverts are “more cinnamon instead of cinnamon-buffish,” then extraordinary care must be made to rule out alternative hypotheses and interpretations.  I am also concerned that some of the perceived color differences could be caused by postmortem changes caused by fumigants, solvents, or preservatives.  Structural colors as well as pheomelanin in hummingbirds can be affected.  Weller said that he detected no postmortem color change or chemical preservation effects on plumage color, but he failed to present any quantitative data to document that assertion (e.g., peak wavelength vs. date of collection).

“It is not clear from the paper whether Weller was able to directly compare the critical specimens (for example the AMNH specimens of H. viola with the type specimen of “H. splendidus” from Bonn).  This is important.  Weller did not claim that gorget color in males of the two supposed species was different, but panel A (Fig. 2) gives the impression that gorget colors do differ.  Is panel A a composite of two different photos?  The holotype (ZFMK 9152) of “H. splendidus” is shown in both panel A and panel B (Fig. 2).  In panel B, the gorget color of “H. splendidus” is much more similar to that of H. viola in panel A. In any case, the figure illustrates how minor differences in observation angle or in photographic conditions can produce widely varying results.”

 

Comments from Zimmer: “NO.  The case for recognition of the new species and the new subspecies seems pretty weak to me, and rests purely on subtle morphological distinctions that (as far as I can gather) are “average” differences in continuously varying traits rather than truly diagnostic differences in discontinuous character states.  Even the purported parapatry/sympatry may be compromised by the migratory status of the birds involved.  I think we need more evidence before recognizing this split.”

 

Comments from Stiles: “NO.  Several aspects of this description are disturbing.  The differences between the two putative species are subtle and are not adequately shown in the illustrations.  The figure of the two males shows them isolated from any background, and thus makes direct comparisons vs. a standard impossible - for instance, one cannot tell whether adjustments of colors were made on one but not the other, etc.  The arguments for sympatry (or parapatry) are shaky at best:  given the mobility of hummingbirds in response to changes in flower availability the data are subject to alternative explanations.  I find it implausible to fit two species, one with two subspecies, within the range of species having a rather restricted distribution to begin with - at the least, genetic data would seem important for documenting this (not to mention some fieldwork!).”

 

Comments from Pacheco: “NO.  Devido ąs incertezas existentes e aos comentários dos colegas acima.”

 

Comments from Jaramillo: “NO. The evidence provided is weak, and I would prefer additional data before changing the taxonomy.”

 

Comments from Nores: “NO. It seems to me a subspecies of Heliangelus viola, for two reasons: 1) The color patterns of the two species are very similar; the differences are very subtle; 2) The parapatric distribution is more characteristic of a subspecies than of species.”

 

Comments from Robbins: “NO, for all the reasons pointed out by Gary Graves.”

 

Comments from Stotz: “NO.  I won’t say it is impossible that there are two species within viola, but it seems unlikely.  I guess I would have to disagree with Weller that the variation he describes is equivalent to other sunangels.  To my untrained eye, even the reasonably similar exortis/micraster pair looks more distinctive than these birds, especially in gorget color.  Is it reasonable to think that two very closely related species of hummingbirds would show only subtle variation in body plumage and essentially none in the gorget and frontlet?  Closest I can think of is Allen’s and Rufous hummingbirds, which have some pretty obvious body plumage variation as well as tail feather shape variation.  All of the other Heliangelus have a distinctive frontlet or gorget or both.

“The Field Museum has 5 specimens of “viola”, all of which would be splendidus based on range, including both subspecies.  The photos of the holotype look bluer in body plumage than any of our 5 specimens.  Don’t know what that means.  I feel like the difference between the gorget color of splendidus and viola shown in Figure 1 could be due to the angle the birds when photographed.  Certainly I could get that color by twisting specimens relative to the light.   There are 2 of our 5 specimens that to my eye look slightly less rosy and more violet, these are our 2 Peruvian specimens, one of which is the Abra Celendín specimen that Weller mentions as varying from typical splendidus by throat color and a more coppery crown (I would agree with this characterization).  The other is from farther south in Cajamarca, Hacienda Sunchubamba (a Koepcke specimen).  Besides the throat it also has a greener, less blue-green crown.

“ Problems I have with the description include the diagnosis.  It says the breast and frontlet are “more bluish-green,” but is that bluer than viola or greener than viola?  I am guessing bluer, but that is not certain in my mind.  It also says “gorget patch rather purplish.” Is that a contrast with viola?  It further says “[gorget] in females enlarged and broadened towards the breast.”  Is that a contrast with viola or with males?  In general, because viola is never described and because the differences are not given in a simple, one-to-one comparison, it is very difficult to really understand what the differences between splendidus and viola are really supposed to be.  In the intro, Weller says  “particularly females of northern representatives differ strikingly from those of H. viola in their throat pattern.”  This is something that I can’t evaluate because the throat pattern of female viola is never described.

“The issue of sympatry is a hard one to get a good handle on.  These are critical data, but the number of specimens and what specific specimens are involved are not provided.  I know that the FMNH specimen from Abra Celendín is part of that potential area of sympatry, but there is no information on what specimens of viola there are from Celendín, and no information on either species from Levanto.  This makes trying to follow up on this issue difficult.  Weller states that “splendidus” is partially migratory and references Ridgely and Greenfield (2001), but I see no mention of migration there.  This actually helps his case, but only slightly.

“I have a hard time with the idea that the MaraĖon was a sufficient barrier to gene flow that speciation occurred, but it is a weak enough barrier that birds have dispersed across it in recent years in both directions (unless this is a seasonal movement of some kind)—viola from west to east to overlap with splendidus at Celendin, and splendidus from west to overlap with viola at Levanto.”

“Weller could be right and there could be 2 species within viola, but I think a better case has to be made.”

 

Comments from Remsen:  NO.  I have waited until Doug checked the specimens to comment on this proposal just in case there was some chance that those data would be convincing.  I would agree with all the comments above, from Gary Graves’ through Doug’s, but I would also add that this is a CLASSIC example for why editors should not publish in the journal they edit.  There are so many problems in this paper, from omitted details to lack of clarity to the conclusion itself that I am certain that this paper could not have been published in its current form anywhere but in this journal, with this editor, with his two reviewers being his former advisor, K.-L. Schuchmann, and an officer in the NOS, John Rappole, who is not a taxonomist and does not work with hummingbirds or Andean birds.  Weller might have a new taxon here, but I think he did himself a disservice by publishing this in the way he did.”

 

Comments from Pérez-Emán: “NO. Weller has not provided strong evidence to make a strong case for splitting Heliangelus viola into two species. However, I must disagree with Van's comments. Although it is worrisome the reviewing process did not catch any of the clear weaknesses suffered by this manuscript (which might have been helpful to potentially improve the manuscript), we cannot judge a journal by the specific review of a manuscript. Different people have discussed problems with the peer review system and it is clear a complex problem that is common to most journals. Discrediting Ornitología Neotropical (ON) for publishing a particular manuscript, which we believe does not meet specific standards, is to confuse things and does not do a good service to Neotropical ornithology. Ornitología Neotropical as a journal has grown a lot since its first days and currently I think it is a great option to publish results from Neotropical research on birds. I have read great contributions published in ON and many of us have published articles in this journal (which I assume is a result of its acceptance as a good journal). Moreover, I believe it provides opportunities for young scientists to publish their good quality work. Thus, it is important to keep separate our evaluation of a scientific proposal from our inferences made about the journal in which it has been published."

 

Response from Remsen: “This is not a judgment on the journal or NOS, but rather on this particular paper, the editor, and the process by which the author published it.  Note that its publication took up pages that could have been used by the many deserving young scientists who have published in ON.”