Proposal (756) to South American Classification Committee

Recognize Campylopterus calcirupicola as a valid species

Effect on South American CL: This proposal would add a recently described hummingbird species to our main list.

The montane Campylopterus largipennis diamantinensis is isolated from the predominantly lowland Amazonian Campylopterus largipennis (including the nominate taxon) by more than 800 km of dry open intervening habitats, the “dry diagonal” formed by the Caatinga, Cerrado, Pantanal, and Chaco. This large disjunction was broken by some anomalous records, usually overlooked in the literature. Lopes and colleagues (2017) have shown that these intervening records represent an undescribed taxon, after examination a large sample of C. largipennis complex museum specimens (more than 1,000), extensive field observations on habitat preferences, and discovery of areas of parapatry without evidence of interbreeding.

Lopes, Vasconcelos & Gonzaga (2017) described a new species of Sabrewing, Campylopterus calcirupicola (Dry-forest Sabrewing) from deciduous forests below 1,000 m of north of state of Minas Gerais and northeastern state of Goiás on Central Brazil. The new species is known from 34 specimens from eight localities. The range of C. calcirupicola probably extends to southeastern state of Tocantins and the southern part of the state of Piauí, from where there are sight records of “C. largipennis”.

Preferred habitat of the populations of C. largipennis found in eastern Brazil (“campos rupestres” and dry forests) contrasts sharply with the humid habitats of the three Amazonian subspecies.

The new species is very similar to the parapatric C. diamantinensis of high altitude “campos rupestres” above 1,000 m a.s.l., differing from it by its smaller size and longer light tail tips, as well as by sternum measurements. Campylopterus calcirupicola differs from C. l. obscurus and from C. l. aequatorialis by its smaller size; basal half of outer rectrices bright bronze green, instead of bright bluish black. It differs from C. l. largipennis by its smaller size; bases of outer rectrices bright bronze green instead of bright bluish black.

The rationale used by authors for considering C. calcirupicola as an independent species is based on Helbig et al. (2002): “diagnosable taxa that are strictly parapatric (…) and do not hybridize (…) [i.e. diamantinensis and calcirupicola] will be ranked as species, because it appears unlikely that such a situation can be maintained without intrinsic reproductive isolation”. This rationale also applies to the PSC concept. Most followers of the BSC might argue that C. calcirupicola is best considered a subspecies of C. diamantinensis, or even that these two taxa should be lumped with C. largipennis. Nevertheless, the parapatric distribution without evidence of free gene flow between C. calcirupicola and C. diamantinensis could be a prima facie evidence for species rank also under the BSC (Remsen 2015).

Recommendation: I recommend a "YES" vote on accepting this Sabrewing as a new species to our list.

Literature Cited:

Helbig, A.J., Knox, A.G., Parkin, D.T., Sangster, G. & Collinson, M. (2002) Guidelines for assigning species rank. Ibis 144, 518–525.

Lopes, L. E., Vasconcelos, M. F., and Gonzaga, L. P. (2017) A cryptic new species of hummingbird of the Campylopterus largipennis complex (Aves: Trochilidae). Zootaxa 4268 (1): 001–033.

Remsen, J.V. Jr. (2015) Book review: HBW and BirdLife International Illustrated Checklist of the Birds of the World Volume 1: Non-passerines. Journal of Field Ornithology 86, 182–187.

José Fernando Pacheco, Sep. 2017

Note from Remsen: If the proposal passes, I think it would be a good idea to do a separate proposal on English names. “Dry-forest Sabrewing” is ok but I wonder if “Limestone Sabrewing” might be better (because most dry forests don’t have this species)?

Comments from Stiles: "YES to splitting calcirupicola from diamantinensis; the morphological and ecological differences and near-parapatry seem convincing, especially given the good sample sizes, although I do wonder whether sampling was attempted in the intervening elevations. Genetic data could clinch this case."

Comments from Areta: "YES. The parapatry and morphological differences in an adequate biogeographical context support the recognition of this overlooked Brazilian endemic."

Comments from Zimmer: “YES, on the grounds that it is a diagnosable taxon with a parapatric distribution relative to its presumed closest relative.”

Comments from Remsen: “YES. Parapatry without free gene flow is sufficient evidence for treatment as a separate species.”

Comments from Claramunt: “NO. I agree that the fact that calcirupicola and diamantinensis are nearly parapatric can be used to evaluate the species status but the critical evidence was not shown in the paper. First, they are not truly parapatric but “near-parapatric”. Second, a crucial piece of evidence was not presented: a plot of PC1 versus latitude. Samples roughly align along a North-South transect that could have been used to see if the variation is clinal or not, whether samples near the contact zone show signs of intermediacy or not. The difference in habitat is a confounding factor rather than an additional piece of evidence: phenotypic differences may be the result habitat-related selection (or even a non-genetic environmental effect) within a single species. I agree that the data is suggestive of two independent linages, given the separation in the morphometric space, but the absence of a critical piece of evidence in this borderline case forces me to vote NO.”

Comments from Robbins: “After reading Santiago’s comments, I’m more on the fence on whether calcirupicola should be given species status. Nonetheless, there appear to be both plumage (tail) and size differences between calcirupicola and the other taxa, and the near-parapatry with diamantinensis, sways me, for now, to recognize calcirupicola as a species.”

Additional comments from Remsen: “Santiago has an excellent point, one that should have been addressed in the paper. However, I have to think that the authors’ careful analysis of specimens would have revealed to them whether there were a gradient in these characters, with the endpoint being calcirupicola and would have proceeded no further.”