Proposal (744) to South American Classification Committee

Transfer White-lined Antbird from Percnostola to Myrmoborus

Effect on SACC: This proposal would transfer the White-lined Antbird (Percnostola lophotes) to Myrmoborus.

Background and analysis: Percnostola lophotes was described by Hellmayr and Seilern (1914) from specimens collected by Watkins in Puno, Peru. Both sexes were described. Later, Berlioz (1966) described a male thamnophilid collected in Madre de Dios, Peru, as Percnostola macrolopha. Parker (1982) mist-netted a mated pair of thamnophilids (and later collected a series) in Madre de Deus and found that the male was "nearly identical" to the male described by Berlioz and that the male described by Hellmayr and Seilern "agrees closely with female-plumaged specimens, with the exception of the blackish primary coverts of their bird, a characteristic of male lophotes," and thus presumably a subadult male. Parker then provided the first natural history information for the species. He noted that in vocalizations and behavior P. lophotes was "quite unlike" its supposed congeners, and he suggested there were similarities with Thamnophilus, Sakesphorus and Myrmeciza species. Since then, in discussion and publications (e.g., Zimmer and Isler 2003) field ornithologists have expressed doubt regarding the generic placement of P. lophotes, but a supported recommendation for its generic placement was never advanced.

In a study aimed to test the monophyly of the genus Myrmeciza, a framework of DNA-based phylogenetic relationships was prepared incorporating Myrmeciza species and their closest relatives including Percnostola and Myrmoborus species (Isler et al. 2013). Maximum-likelihood and Bayesian analysis produced similar typologies indicating with high support that P. lophotes was imbedded in a subclade consisting of Myrmoborus species and was sister to M. melanurus. This was at first a surprise (this placement had never to our knowledge had been suggested in the literature) but then became a "why hadn't we seen this” when the phylogeny was overlaid with morphological and behavioral characters (see Zimmer and Isler 2003, Isler et al 2013). Putting aside the crested look of P. lophotes, its plumage resemblance to M. melanurus is obvious, a similarity never been mentioned in the literature perhaps because of the limited and disconnected ranges of the two species. Morphometric proportions of bill and tail, which helped direct Hellmayr to place lophotes in Percnostola, are similar between Percnostola and Myrmoborus species so they are of no consequence in the shift. The lowland, near-river-edge habitat preferences of P. lophotes (with bamboo) and M. melanurus are generally similar and differ from the typically upland, often sandy-soil, habitats of Percnostola species. The domed nest of P. lophotes, placed in bamboo debris on the ground closely resembles the nest of M. leucophrys (Lebbin et al. 2007). Domed nests of Percnostola species are similar, although sometimes placed slightly above the ground.

Recommendation: We recommend a "YES" with regard to recognizing Myrmoborus lophotes.

References:

Berlioz, J. 1966. Descriptions de deux espèces nouvelles d'oiseaux du Pérou. L'Oiseau et la Revue Française d'Ornithologie 36:1–3.

Hellmayr, C.E., and J. G. von Seilern. 1914. Neue Vögel aus dem tropischen Amerika. Verhandlungen der Ornithologischer Gesellschaft in Bayern 12:87–92.

Isler, M. L., G. A. Bravo, and R. T. Brumfield. 2013. Taxonomic revision of Myrmeciza (Aves: Passeriformes: Thamnophilidae) into 12 genera based on phylogenetic, morphological, behavioral, and ecological data. Zootaxa 3717 (4): 469–497.

Lebbin, D. J., P. A. Hosner, M. J. Andersen, U. Valdez, and W. P. Tori. 2007. First description of nest and eggs of the White-lined antbird (Percnostola lophotes), and breeding observations of poorly known birds inhabiting Guadua bamboo in southeastern Peru. Boletín SAO 16:119–132.

Parker, T. A., III. 1982. Observations of some unusual rainforest and marsh birds in southeastern Peru. Wilson Bulletin 94:477–493.

Zimmer, K. J., and M. L. Isler. 2003. Family Thamnophilidae (typical antbirds). Pages 448–681 in Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos (J. del Hoyo, A. Elliot, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain.

Morton L. Isler, Gustavo A. Bravo, & Robb T. Brumfield, March 2017

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Comments from Remsen: “YES. Solid genetic data. Interesting case of phenotypic similarities to congeners overwhelmed by one prominent feature on the head.”

Comments from Jaramillo: “YES. This would make a nice article for the general birding public to illustrate how some obvious morphological features on a bird can mask equally obvious non-visual information and cloud the understanding of relationships in birds. It is an interesting story. But cutting to the chase, yes, it is clear that this species needs to be transferred to Myrmoborus.”

Comments from Zimmer: “YES. Plumage, structure, habitat, nest architecture, vocalizations, and (if memory serves me) even stereotypical tail movements all conform with what the genetic evidence suggests.”

Comments from Areta: "YES. Clear genetic evidence supports this move and is further supported by plumage and natural history data."

Comments from Stiles: "YES. Genetic and plumage data (except the crest) are sufficient for this transfer."

Comments from Robbins: "Yes, the genetic data leave no doubt that lophotes should be transferred to Myrmoborus."

Comments from Pacheco: "YES. Although not previously suspected, there is clear support of genetic and morphological data for this transfer."

Comments from Claramunt: "YES. The data are robust, and the solution simple."