Proposal (673x) to South American Classification Committee
Recognize Nyctiprogne leucopyga latifascia as a species
The original Proposal 673 (see below) advocated splitting Nyctiprogne leucopyga into two species , based mainly on the genetic data of Sigurdsson & Cracraft (2014); the name given for the second species was N. latifascia. This proposal was accepted by SACC. However, the discussions regarding the split disclosed several underlying problems. To begin with, the distributions of the two species were very incompletely known; no clear differences in plumage or morphology were available (beyond the impression that these are “subtle”). Likewise, apparent differences in vocalizations were mentioned but not tied to specific specimen evidence or details on localities. Finally, based on examination of the illustration of N. leucopyga in Spix (1825) and the description of latifascia by Friedmann (1945), Piacentini concluded that the latter was indistinguishable from nominate leucopyga and therefore is a synonym of leucopyga, thus leaving the second species without a name. Given these problems, SACC has refrained from implementing the split pending their resolution.
Recently we received a communication from Nigel Cleere (in press) that presented a satisfactory nomenclatural resolution. He presents detailed information on morphology and distributions that clarify the recognition of the two species. He confirms Piacentini’s judgment that latifascia is a synonym of leucopyga and that the second species should be known as N. minuta Bonaparte 1850, and that the additional subspecies since described pertain to minuta, also giving more details on their ranges and distributions. There remains much to do to obtain details of the distributional limits of the two species. For example, examining the specimens in the ICN collection, I found that both occur in Colombia: two specimens from Mitú, Vaupés are clearly leucopyga, whereas one from Arauca, two from Casanare, plus a recording that I made from western Meta are clearly minuta.
To summarize briefly the more trenchant details of the morphological differences between the two species as given by Cleere:
N. leucopyga: larger (wing length 133-150mm, tail length 83-100mm), more blackish in general coloration, with the primaries dark brown without pale markings; the white band of the tail is slightly broader but closer to the base of the tail, largely overlapped by the undertail coverts (47-51 mm from the tail tip).
N. minuta: smaller (wing lengths 123-136mm, tail lengths 82.99mm), except for the southernmost subspecies majuscula, which is actually at least as large as leucopyga ( wing lengths 145-158mm, tail lengths 100-113mm); more brownish overall especially below, the primaries dark brown with cinnamon spots on the outer webs (evident in the folded wing); the white band of the tail closer to the middle of the rectrices (30-35mm from the tip of the tail, with little or no overlap by the undertail coverts).
Cleere’s information on vocalizations suggest differences between the two putative species, but is relatively incomplete (no song of leucopyga has yet been recorded). Regarding distribution, Cleere gives that of leucopyga as from the Río Negro east along both sides of the Amazon in Brazil, and west to the Caño Casiquiare (the type locality of latifascia); the ICN specimens indicate that it also reaches extreme eastern Colombia in Vaupés. The ranges of the four subspecies of minuta are given as follows: minuta occurs from the Guianas into eastern Venezuela; pallida from southeastern Venezuela south in the Llanos (the ICN specimens indicate to at least northern Casanare in Colombia; exigua (distinguished by its darker, blacker coloration) may extend from southern Casanare (based on the blacker coloration of the specimen from Maní) and southwestern Brazil south to at least the Amazon); majuscula occurs from northeastern Perú and southern Brazil to Bolivia and Paraguay. He states that intergrades are known from areas where the distributions of minuta and pallida and the latter and exigua approach or abut (the Maní specimen in ICN could represent such a case), but no intergrades are reported between the large majuscula and the small exigua, perhaps because their ranges do not abut. The net result of these data places the distribution of leucopyga along the Amazon and at least the eastern Río Negro into extreme eastern Colombia; that of minuta describes an arc effectively surrounding that of leucopyga from the Guianas and southern Venezuela south along the llanos to the upper Amazon of northeastern Peru, southwards through southern Brazil into Bolivia and Paraguay. It is not unlikely that the distributions of these two putative species could overlap in southeastern Venezuela, eastern Colombia, Ecuador and northern Peru, but this remains to be demonstrated.
Turning to the genetic analysis by Sigurdsson & Cracraft, they found two clearly differentiated clades within leucopyga as previously defined, but there is no indication that they analyzed in any detail the plumages of their specimens, and their information on distributions was also evidently incomplete. The first clade included two specimens of latifascia from southern Venezuela and one from “Amazonian Brazil” which they also included as latifascia: they applied the species epithet latifascia to this clade. The second clade included two specimens of majuscula from Paraguay and Bolivia, and one specimen from Guyana; they applied the name leucopyga to these. However, Cleere showed that the distribution of leucopyga extends westward along much of the middle Solimões-Amazon, such that the “Brazilian Amazon” specimen could well be leucopyga. Cleere also gave the distribution of nominate minuta as extending to Guyana, such that the specimen of the second clade they considered to be leucopyga is most likely minuta (this also would tend to substantiate his inclusion of both majuscula and the three northern subspecies in minuta, despite the differences in size). In sum, I consider that the first clade of Sigurd & Cracraft should be designated as leucopyga (not latifascia) and the second clade as minuta (not leucopyga). This brings nomenclature and the genetic, plumage and distributional data into line and supports the recognition of these two clades as distinct species.
Gary Stiles, December 2019
Comments from Pacheco: “A tentative YES. Assuming that there are unequivocally two taxa (cf. Sigurdsson & Cracraft, 2014) and that the application of Caprimulgus minutus Bonap and Caprimulgus leucopygus Spix to each of them is correct (Nigel Cleere, in press), I am in favor of this proposition.”
Proposal (673) to South American Classification Committee
Note: proposal on hold until nomenclature resolved; see Piacentini comment
Recognize Nyctiprogne leucopyga latifascia as a species
Effect on SACC: Would elevate current subspecies Band-tailed Nighthawk Nyctiprogne leucopyga latifascia to species level.
Sigurdsson & Cracraft (2014) presented a DNA-based phylogeny of the caprimulgids that included sampling of taxa that has not been included in prior works. This included the first genetic data for the taxon Nyctiprogne leucopyga latifascia (sample from near type locality). Their data demonstrated that this southern Venezuelan taxon is not sister to Nyctiprogne leucopyga (samples from Guyana, Bolivia and Paraguay). They found over 8% divergence in ND2 and 7% divergence in Cytb sequences between those two taxa. The samples representing Nyctiprogne leucopyga are more closely related to Nyctiprogne vielliardi and those are sister to latifascia. As a point of reference, they found 2.6% difference between leucopyga and vielliardi.
Plumage morphology is very conservative within Nyctiprogne. Friedmann (1945) described latifascia as a species and noted that it was darker and less vermiculated than other Nyctiprogne taxa. He outlined the distribution of latifascia as: “extreme southern Venezuela, from San Carlos on the uppermost reaches of the Rio Negro to Raudal Quirabuena on the Brazo Casiquiare”.
Recommendation: Much still needs to be confirmed on the distribution and potential vocal differences within Nyctiprogne (e.g. comments on geographic variation on voice in Nyctiprogne in Alvarez Alonso and Whitney 2003). Also note that Sigurdsson & Cracraft lacked two taxa described as subspecies of leucopyga. Nonetheless, based on the recent genetic data there are clearly at least two species involved in what is currently recognized as a single species. Therefore, I recommend that latifascia be elevated to species status.
If proposal passes; English name: Given the very subtle plumage differences and that latifascia is much more widely distributed than what Friedmann indicates (fide B. Whitney), the English name is not obvious. Bret Whitney has suggested Rattling Nighthawk as an appropriate English name given that there are no definitive plumage characters or unique geographic aspect to this species’ distribution.
Friedmann H. 1945. The genus Nyctiprogne. Proceedings of the Biological Society of Washington 58: 117–120.
Sigurdsson, S. and J. Cracraft. 2014. Deciphering the diversity and history of New World nightjars (Aves: Caprimulgidae) using molecular phylogenetics. Zoological Journal of the Linnean Society. 170:506–545.
Whitney, B. M., J. F. Pacheco, P. S. M. Fonseca, R. E. Webster, G. M. Kirwan and J. M Barnett. 2003. Reassignment of Chordeiles vielliardi Lencioni-Neto, 1994, to Nyctiprogne Bonaparte, 1857, with comment on the latter genus and some presumably related chordeilines (Caprimulgidae). Bull. Brit. Orn. Club 123:103-112.
Mark Robbins, July 2015
Comments from Remsen: “YES. The genetic data alone require elevation of latifascia to species rank. This is one case in which the genetic distances and the branching patterns alone are sufficient evidence. If the proposal passes, I would recommend a separate one on the English name. “Cryptic” it may be, but I worry that “cryptic” in general is overused and becoming trite. Not that I have any better suggestions, but let’s see what the other options might be.”
Comments from Zimmer: “YES. The genetic data alone would be sufficient for recognizing latifascia as specifically distinct from leucopyga. However, the vocal differences are also significant, and having seen and recorded both taxa in the field, I concur strongly with splitting the two. The morphological distinctions are subtle (at least during the crepuscular hours when Nyctiprogne are most active), although latifascia does appear noticeably duskier in general color tone. What I am assuming is latifascia (by voice) is seemingly widespread but patchily distributed compared to more widespread and more evenly distributed leucopyga. I’ve seen latifascia at various points along the rio Negro, including the Anavilhanas Archipelago and in the Jaú, but also south of the Solimões/Amazon along the rio Javarí on the Brazil-Peru border. In Brazil, they seem to be more tied to black water rivers and lagoons, whereas leucopyga is seemingly more catholic in its habitat preferences, occurring widely in white water and black water in Amazonia, as well as in places south of the basin (e.g. the Pantanal and the Araguaia). However, there are some black water regions on the South Bank where I have only recorded leucopyga, and I have seen the two taxa virtually side-by-side along portions of the rio Negro. So, bottom line is, although I think there may be some habitat-preference distinctions between the two, I don’t think we know enough yet to really say with any certainty. Similarly, given that latifascia is more widely distributed than previously recognized, and that it can and does occur in syntopy with leucopyga and given that there are additional described subspecies of N. leucopyga sensu lato, it is going to be difficult to ascribe any morphological distinctions observed in museum specimens to any particular taxon in the complex with any real degree of certainty. I know that Mario Cohn-Haft and Bret Whitney have been working on this problem for ages, and they, no doubt, could offer much more detailed insight. However, I don’t think that there is any doubt that there are at least two species-level taxa currently nested under Nyctiprogne leucopyga, and that latifascia (which, given its widespread, but patchy distribution, may itself prove to be polytypic), at the very least, should be split out.”
Comments from Stiles: “YES. The case for species status of latifasciata seems solid, although it looks like there is still much to do to fully understand species limits among the other forms of Nyctiprogne.”
Comments from Pacheco: “NO. I also think evident - by direct experience in Rio Negro - that there are two taxa of Nyctiprogne in northwestern Amazonia. As highlighted by Kevin, the distribution of latifascia is greater than thought before, and several regions should have the pair of Nyctiprogne coexisting. There is, however, a problem not resolved by the Sigurdsson and Cracraft: which of the two implicated taxon should be called leucopyga? In nomenclatural terms, given the morphological similarity between these two taxa and because the type of leucopyga described by Spix is lost (vaguely from "Amazon River") the correct application of leucopyga needs to be solved before adopting the split.”
Comments from Areta: “NO. I agree with Fernando's view on the need to do the proper taxonomic job of reviewing/designating type specimens. I am concerned (and have expressed this view before) with making decisions based on phylogenetic results when the taxonomic portion of the work has not been done. It seems clear that two Nyctiprogne species are present in several Amazonian rivers, but before assigning a name to a vocal type, the formal taxonomy needs to be worked out. It is tempting to assume that taxonomic issues have been solved before, but generally large-scale phylogenetic papers simply rely on what is out there without making critical evaluations of type specimens, original descriptions, etc. I am not saying that they should do that if they do not propose taxonomic changes, but if they do enter into the taxonomic realm, then yes, they should do their homework to provide a solid foundation.”
Additional comments from Remsen: “In response to the points made by Fernando and Nacho above, I reaffirm my YES vote, and here is why. This is a case in which the existence of two species is more important, in my opinion, than what to call them. Better to start calling the two taxa by the names currently applied to the two populations than to obscure biodiversity by ignoring them. Resolution of the problem that Fernando outlines requires, in my view, a separate bit of research, including declaration of a neotype if the type for leucopyga. That might take years. Furthermore, whomever does that research will certainly pick a neotype that matches the currently understood phenotypic characters of leucopyga, perhaps even with DNA sample. Because the type of leucopyga is lost, we will never know if it was or was not actually a latifascia, and whoever selects a neotype will obviously pick a specimen with the plumage features currently associated with the name leucopyga. Therefore, unless I am missing something, there is no chance of any reversal in what we currently understand the two names to apply to. Meanwhile, biological reality is that there are two species, for better or worse referred to as leucopyga and latifascia, with diagnosably different plumage, etc. Note that Sigurdsson and Cracraft’s sample of latifascia was from near the type locality, and given the genetic distance, I think it is safe to assume that that sample represents something very different from their leucopyga samples. Although I agree with Nacho that too often phylogeneticists don’t do their homework in terms of nomenclature, I do not think that we could have expected Sigurdsson and Cracraft do any more than they did (assuming they corroborated IDs of their vouchers), and I see no point in delaying a biology-based decision on a point of nomenclature that, even if eventually resolved, will produce the same outcome, i.e. stability in terms of what we call leucopyga. I recommend a YES vote, with a note in our official Note summarizing our concerns over potential problems in nomenclature. Fernando’s point as well as the subsequent discussion will also be available, of course, here at the SACC site. Worst case scenario is that we eventually have to use different names than those we use now, which can be remedied by the proposal system.”
Comments from Jaramillo: “YES. Based on the molecular data, and thanks to Kevin in particular for filling in more details regarding the birds in the field, voice, habitat etc. I will wait for a proposal on the English Name, and would love one that is based on voice. I agree with the points made by Van. But also would add that like it or not, we do not work in a vacuum. We do have constituents that await our decisions, whether other scientists, birders, conservationists etc. Although we are independent and need to act on the science, we should not ignore some of the critiques that are out there regarding taxonomic committees in general, and ours specifically, although I tend to think that the SACC is generally well regarded because of transparency. But there is a concern that there are data out there that we are not addressing (maybe we are lacking proposals?), that we move slowly, that we may be “too” conservative etc. In this case, we have the data to move, to separate two species and I doubt that is a concern here on that. Let the other part of the job come after, what the names are, these things can be sorted out in time…like the Chapada Flycatcher for example. It is not pretty to have to make a change like that, but it works. I say, YES, and sort out any possible nomenclatural issues later if they turn up. I think that the authority of the committee is strengthened when we can act quickly and clearly, based on strong data like this. Our constituents like it when we listen to biology, and act less like lawyers seemingly more interested in nuances of procedure than in a correct accounting of biodiversity.”
Comments from Cadena: “YES, albeit with some hesitation. Although sampling of leucopyga is rather sparse given the wide distribution of this taxon, the branching pattern appears clear. However, I note that paraphyly by itself is not a criterion we have considered (for good reasons, I think) as sufficient to split taxa at the species level; specifically, leucopyga (including the nominate subspecies and latifascia) may well be considered a paraphyletic species within which a reproductively isolated vielliardi species is nested. I see there are good arguments here suggesting that this is not the case, as nominate leucopyga and latifascia differ vocally and may have interdigitating/sympatric distributions. As far as I know, however, the information on vocalizations and distributions has not been analyzed nor published – please correct me here if I am wrong. The lack of published analyses notwithstanding, I think that the fact that this taxon was originally described as a species and later lumped with leucopyga with (presumably) no clear rationale, together with the current molecular data, puts the burden of proof on demonstrating these taxa are conspecific, and thus I am OK with the split. I appreciate the importance of comments by Fernando and Nacho about the need to solve the taxonomy, but here I agree with Van that this could be sorted out later on. Knowing there are already two species and not recognizing them because of arguably minor uncertainties about names would seem like a more important mistake than proposing a classification that better reflects what we know about the number of species-level taxa in which names turn out to be mistaken.”
Comments from Piacentini: “After reading the comments on the Nyctiprogne case, I thought I’d better write a comment before this change is implemented in your SACC list. With all due respect, but putting in straight words, I believe you are not doing a good service to Neotropical ornithology by approving it.
“The main argument put forward in favor of the adoption of latifascia is that “biological data” should overcome nomenclature stability/correctness. It is sad to see such a point of view. In addition to the above argument, I’ve noticed that some members have completely misunderstood what is going on and what are the possible nomenclatural consequences of treating latifascia as distinct from leucopyga. Last, I call the attention to our recent checklist of birds of Brazil (Piacentini et al. 2015), in which we bring information on the case that you all are overlooking.
“As Pacheco said in his comment to the case, the application of the name leucopyga is an issue to solve. But since then, new data were published. Here is the note we bring in our checklist of the birds of Brazil:
“Molecular data (Sigurdsson & Cracraft 2014) have showed that at least two species are involved, a conclusion already suspected based on voice. Nonetheless, based on the original illustration of Spix (1825; the type is lost fide Hellmayr 1906), the bird commonly referred to as latifascia is actually the true leucopyga, leaving the question open as to the correct name to apply to the second species - the one sister to N. vielliardi in Sigurdsson & Cracraft (2014).”
“What does that mean? That SACC will consciously apply a wrong name (latifascia) to the true leucopyga, whereas wrongly calling a second species leucopyga. And that in a few years you will need not only to “update” the name of latifascia, but to invert the application of leucopyga. Maybe the following illustration will help understand exactly what is going on
“Presently: leucopyga =
“Then SACC approved to say: leucopyga =
“Next SACC will need to invert: leucopyga =
“Maybe not everybody is realizing the unnecessary confusion that SACC will introduce by applying names without consistency. This is not comparable to the Suiriri islerorum case, as only the Chapada Flycatcher’s scientific name needed correction, whereas both nighthawk “offspring” species will need correction, with both being called leucopyga at some moment.
“So, the case will be already confusing when we realize that leucopyga will soon have a biological meaning distinct from its current application. Yet, SACC members think that it is fair to introduce a third, unnecessary, and provisional meaning to leucopyga just to say with a few years in advance that it recognizes there are two species involved? That makes no sense! If “biological data” are more important than nomenclature, then I challenge SACC to be consistent and recognize several new species already published in the literature that currently cannot be listed because there are no names available to them:
• Several Scytalopus (see Mata et al. 2009; Hosner et al. 2015 for just a handful of examples);
• the Santa Marta Screech Owl (see Dantas et al. 2015 for data supporting its existence);
• the new Grallaria (aff. rufula) from Hosner et al. 2015; also Winger et al. 2015
“In all those cases, there are biological data supporting the recognition of additional species, but of course SACC will never adopt them prior to the proper publication giving names to them. The Nyctiprogne case is the same: there are data pointing to more than one species (Sigurdsson & Cracraft 2014), but we don’t have a name to apply to the second species (Piacentini et al. 2015).
“As a last comment, some member could argue that it may take years before Mario, Bret, et al. finally set the case. Maybe that is true, but actually that would be a strong case against a provisional change by SACC: the longer they take to publish their data, the longer SACC will lead to new publications applying (wrongly) the name leucopyga in a sense that is neither the current nor the true application of that name. What for?
“Additional literature cited:
Dantas, S. M., Weckstein, J. D., Bates, J. M., Krabbe, N. K., Cadena, C. D., Robbins, M. B., ... & Aleixo, A. (2016). Molecular systematics of the new world screech-owls (Megascops: Aves, Strigidae): biogeographic and taxonomic implications. Molecular phylogenetics and evolution, 94, 626-634.
Hosner, P. A., Andersen, M. J., Robbins, M. B., Urbay-Tello, A., Cueto-Aparicio, L., Verde-Guerra, K., ... & Tiravanti, J. (2015). Avifaunal surveys of the upper Apurímac River Valley, Ayacucho and Cuzco Departments, Peru: New distributional records and biogeographic, taxonomic, and conservation implications. The Wilson Journal of Ornithology, 127(4), 563-581.
Mata, H., Fontana, C. S., Maurício, G. N., Bornschein, M. R., de Vasconcelos, M. F., & Bonatto, S. L. (2009). Molecular phylogeny and biogeography of the eastern Tapaculos (Aves: Rhinocryptidae: Scytalopus, Eleoscytalopus): cryptic diversification in Brazilian Atlantic Forest. Molecular Phylogenetics and Evolution, 53(2), 450-462.
Piacentini, V. D. Q., Aleixo, A., Agne, C. E., Maurício, G. N., Pacheco, J. F., Bravo, G. A., ... (2015). Annotated checklist of the birds of Brazil by the Brazilian Ornithological Records Committee/Lista comentada das aves do Brasil pelo Comitê Brasileiro de Registros Ornitológicos. Revista Brasileira de Ornitologia-Brazilian Journal of Ornithology, 23(2), 91-298.
Winger, B. M., Hosner, P. A., Bravo, G. A., Cuervo, A. M., Aristizábal, N., Cueto, L. E., & Bates, J. M. (2015). Inferring speciation history in the Andes with reduced‐representation sequence data: an example in the bay‐backed antpittas (Aves; Grallariidae; Grallaria hypoleuca sl). Molecular ecology, 24(24), 6256-6277.
Additional comments from Remsen: “[May 2019]: We have now waited four years for resolution of this issue with nothing in print, other than the assertion that the type illustration of latifascia is actually leucopyga.”