Proposal (761) to South American Classification Committee
Change species limits within Machaeropterus regulus
Effect on SACC classification: Change the number of species within the Machaeropterus regulus complex from one to three.
Background: From SACC notes:
Snow (2004b) considered the Amazonian striolatus subspecies group to be a separate species from Machaeropterus regulus of SE Brazil based on <??REF>.
Several publications have recommended the separation of the Atlantic forest population of Machaeropterus regulus regulus from the remaining populations in Amazonia and the Andean and Tepui foothills. The oldest I can find is Whittaker and Oren (1999), in which voice differences were used as the basis for the proposed split. Other authors since (e.g., Snow 2004, Ridgely and Tudor 2009) have followed suit, but others (e.g., Ridgely and Greenfield 2001, Kirwan and Green 2011) have not.
Lane et al. (2017) provided new information on the complex, describing a new taxon, and highlighting voice and morphological characters that strongly suggest that, not only should nominate regulus be separated from the remainder of the named taxa, but that the new taxon described, M. eckelberryi, should also be recognized as a species separate from the rest. M. eckelberryi is restricted to the Cordillera Azul and the hills of the upper Rio Mayo valley of San Martin and Loreto departments, Peru, and is largely found above 500m elevation. M. striolatus is found about 60 km north of the Cordillera Azul, within the same interfluvium, and there are no signs of intergradation between the two taxa.
Analysis and Recommendation:
Among suboscine passerines, voice has become a strong indicator for genetic differentiation, and is widely considered a major pre-zygotic barrier to interbreeding among suboscine passerines. The present case involves three distinct vocal groups, in which the compared “advertising songs” are homologous vocalizations.
The first is the nominate regulus of the Atlantic Forest of Brazil. The song is a monosyllabic descending note:
The advertising song of the members of the widespread “striolatus” group (as defined by Lane et at. 2017) is a bi-syllabic sneezy “cli-CHEW!” with a distinctive undertone (all produced vocally). Although the space between the first and second notes varies (shorter in lowland and Tepui populations and longer in Andean groups in Colombia and Venezuela), the pattern is quite conserved over a wide distributional range:
Finally, the newly described M. eckelberryi has a monosyllabic rising “chewee?” vocalization lacking any undertone:
Furthermore, the nominate M. regulus has noticeably modified primaries, presumably used for mechanical sound production, that are completely lacking among the rest of the taxa within the complex:
Minor plumage coloration differences also exist among these three groups, but these are less impressive, and could easily be taken as “subspecific” variation. I will point out that the plumage of M. eckelberryi is nearly identical to the allopatric M. striolatus aureopectus of the Tepuis, but given the starkly different voices, Lane et al. 2017 concluded that this could be as much due to convergence as to it could indicate a sister relationship between the two taxa. The distributions of the three voice groups are as follows:
Lane et al. 2017 concluded that M. regulus was best considered three species-level taxa based on these voice and morphological characters:
Machaeropterus regulus monotypic
Machaeropterus striolatus containing the taxa striolatus, aureopectus, obscurostriatus, antioquiae, and zulianus.
Machaeropterus eckelberryi monotypic
I will break the vote into two parts and give my recommendations for each:
761A: separate M. regulus from the remaining M. striolatus complex. Recommendation: by virtue of the strong vocal and morphological differences, I recommend a YES for this move.
762B: recognize M. eckelberryi as a species distinct from the remaining members of the M. regulus complex. Again, based on the strong vocal differences, and the fact that M. eckelberryi and M. striolatus come within 60 km of one another but show no signs of intergradation, I recommend a YES for this move.
If both of these votes pass with a YES, the proposed English names for the resulting species could be:
M. regulus Eastern Striped Manakin
M. striolatus Western Striped Manakin
M. eckelberryi Peruvian Striped Manakin
Or, should the committee decide that a compounded name for each seems unnecessary, alternative names could be:
M. regulus Kinglet Manakin
M. striolatus Striolated Manakin
M. eckelberryi Painted Manakin
Kirwan, G.M., and G. Green. (2011) Cotingas and Manakins. Princeton University Press, Princeton, New Jersey, 624 pp.
Lane, D.F., A. W. Kratter, and J. P. O’Neill. (2017). A new species of manakin (Aves: Pipridae; Machaeropterus) from Peru with a taxonomic reassessment of the Striped Manakin (M. regulus) complex. Zootaxa 4320: 379–390.
Ridgely, R.S., and P.J. Greenfield. (2001) The Birds of Ecuador: Field Guide. Cornell University Press, Ithaca, New York, 740 pp.
Ridgely, R.S., and G. Tudor. (2009) Songbirds of South America. University of Texas Press, Austin, Texas, 750 pp.
Snow, D.W. (2004) Family Pipridae (Manakins). In: del Hoyo, J., Elliott, A., and Christie, D.A. (Eds.), Handbook of Birds of the World. Vol. 9. Lynx Edicions, Barcelona, 110–169.
Whittaker, A. and D.C. Oren. (1999) Important ornithological records from the Rio Juruá, western Amazonia, including twelve additions to the Brazilian avifauna. Bulletin of the British Ornithologists’ Club, 119, 235–260.
Dan Lane, December 2017
Comments from Stiles: "A. YES, the morphological and vocal differences and wide geographical separation make species status for regulus seem convincing and logical. B. A more tentative YES: the vocal difference is greater, the morphological differences rather less, but presumed near-parapatry of eckelberryi and striolatus tips the balance, though here again genetic data would really clinch the case. Also worth mentioning is that based on plumage, voice records and genetic sampling of aureopectus from the Tepuis would be interesting."
Comments from Areta: "YES to A and B. Morphological and vocal differences in the homologous advertising songs support the recognition of M. eckelberryi and the separation of M. striolatus from M. regulus."
Comments from Zimmer: “A) YES. B) YES. Lane et al (2017) demonstrated (convincingly in my opinion) that the vocal differences between these three groups (nominate regulus, eckelberryi, and the remainder of the striolatus-group) are significant. The highly modified primaries of regulus as compared to those of the other two groups are also highly suggestive. As noted by the authors, eckelberryi closely resembles aureopectus of the Tepuis, but the voice of the latter taxon (of which I have recorded several individuals [these recordings were included in the analysis by Lane et al 2017]) is indistinguishable (at least to my ears) from those of other striolatus, and therefore, is different from the voice of the morphologically similar eckelberryi. The apparent parapatry of striolatus relative to eckelberryi would seem to provide further ammunition for the argument of recognizing the two as distinct from one another. As for English names, I prefer the more informative compound names (Eastern, Western and Peruvian Striped Manakins) suggested in the proposal, but the simpler, novel names (Kinglet Manakin, Striolated Manakin and Painted Manakin) also have some appeal.”
Comments from Remsen: "YES on A and B. I’ve been familiar with this paper since an initial draft and think that the data solidly support the taxonomic conclusions.”