Proposal (638) to South American Classification Committee
Recognize the genus Cercomacroides (Thamnophilidae)
Effect on SACC: This proposal is for the recognition of a newly described genus for several species currently classified in Cercomacra.
Background: Current SACC footnote 39e summarizes the situation:
‚ÄúFitzpatrick & Willard (1990) and Zimmer & Isler (2003) considered Cercomacra tyrannina, C. laeta, C. parkeri, C. nigrescens, and C. serva form a monophyletic group based on plumage and voice. Tello et al. (2014) confirmed the monophyly of this group and also showed that they are not the sister group to other Cercomacra, thus requiring the naming of a new genus, Cercomacroides, for them.¬† SACC proposal badly needed.‚Äù
Analysis and recommendation: Tello et al. (2014) named a new genus, Cercomacroides, for the species in the ‚Äútyrannina group‚Äù (whistlers), to include the following taxa:
Their molecular data set included three mitochondrial (ND2, ND3, CYTB) and one nuclear intron (FIB5) for a total of 3018 bps. Tello et al.‚Äôs ongoing investigation on the systematics of this group has produced ~5k additional nucleotides (including several nuclear introns) that corroborated the monophyly of Cercomacroides and helped resolved problematic basal nodes within both, Cercomacroides and Cercomacra.
I recommend a YES vote. Morphological similarities that support the monophyly of Cercomacra are vague and maybe plesiomorphic, whereas the recognition of Cercomacra and Cercomacroides as different genera is consistent with plumage, behavioral, and ecological differences (Zimmer and Isler 2003) and is required to retain the monophyly of Cercomacra (s.s.). Recognizing Cercomacroides as a genus is the appropriate taxonomic solution for this particular case.
Fitzpatrick J.W., Willard D. E., 1990. Cercomacra manu, a new species of antbird from Southwestern Amazonia. Auk 107: 239-245.
Tello, J. G., Raposo, M., Bates, J., Cadena, D., Bravo, G., and M. Maldonado. 2014. Reassessment of the systematics of the widespread Neotropical genus Cercomacra (Aves, Thamnophilidae). Zoological Journal of the Linnean Society 170, 546-565.
Zimmer, K. J., and Isler, M. L., 2003. Family Thamnophilidae (Typical antbirds). Handbook of the Birds of the World Vol. 8, 448-681.
Jose G. Tello, August 2014.
Comments from Remsen:¬† ‚ÄúYES.¬† The new data from Tello et al. (2014) require splitting of Cercomacra.¬† Although this genus has long been known to consist of two distinct groups, now we know they are not sister groups.‚Äù
Comments from Zimmer: ‚ÄúYES‚Äù for reasons spelled out in the proposal.¬† As Van commented, we‚Äôve long known there were two distinct groups within Cercomacra (based on plumage, vocalizations, ecology and behavior), but what has changed is that we now have genetic data showing that the two groups are not sisters.¬† Erection of the new genus and transfer of the ‚Äútyrannina-group‚Äù is required to keep Cercomacra as a monophyletic genus.‚Äù
Comments from Stiles: ‚ÄúYES, given the polyphyly of Cercomacra and the fact that including the intervening genera in an expanded Cercomacra would produce an undiagnosable soup, recognizing Cercomacroides is clearly desirable.‚Äù
Comments from Jaramillo: ‚ÄúYES ‚Äì The molecular data matches up well with morphological, and ecological data to clarify that these two groups are different. But more importantly, they are not sisters, needing the change of part of Cercomacra to Cercomacroides.‚Äù
Comments from Stotz: ‚ÄúYES.¬† Not completely intuitive split, but the two subunits of Cercomacra have always been clearly defined, and this split is consistent with those units based on voice and to a lesser extent plumage.¬† So I am confortable with the split, even though I am surprised that the two groups are not sister.‚Äù
Comments from Pacheco: ‚ÄúYES, with strong evidence, well presented in the work of Pepe and colleagues.‚Äù