Proposal (518) to South American Classification Committee

Recognize the genus Isleria for two "Myrmotherula"

Effect on SACC: This would transfer two species from their current placement in Myrmotherula to Isleria, the genus newly described for them.

Background: SACC currently classifies 27 species in the genus Myrmotherula. The traditional plumage-based taxonomy of the genus was considered problematic by earlier authors (i.e. Cory & Hellmayr, 1924; Peters 1951), and several subsequent studies indicated that Myrmotherula is polyphyletic (Hackett & Rosenberg, 1990; Irestedt, et al., 2004; Brumfield et al., 2007). Myrmotherula hauxwelli was shown to be a distant relative of other members in the genus (Gómez et al., 2010), and morphological, ecological, and behavioral differences support its close relationship with M. guttata (reviewed by Zimmer and Isler, 2003). However, the phylogenetic position of these two species has remained unknown.

New information: Results from a subset of taxa from a densely sampled molecular phylogeny of the Thamnophilidae (including 214 of 220 species) confirmed that Myrmotherula guttata and M. hauxwelli are only distantly related to other species in Myrmotherula, including its type species M. brachyura, and showed that they are sister to the genus Thamnomanes (Bravo et al., 2012). Because levels of phenotypic, ecological, and behavioral divergence between guttata-hauxwelli and Thamnomanes do not warrant merging these species into a larger genus Thamnomanes, the genus Isleria was described for I. guttata and I. hauxwelli (see Bravo et al., 2012).

Recommendation: We recommend a “YES” vote to recognize the recently described genus Isleria for “Myrmotherula” guttata and hauxwelli.

References:

BRAVO, G. A., R. T. CHESSER, & R. T. BRUMFIELD. 2012. Isleria, a new genus of antwren (Aves: Passeriformes: Thamnophilidae). Zootaxa 3195: 61-67.

GÓMEZ, J. P., BRAVO, G. A., BRUMFIELD, R. T., TELLO, J. G. & CADENA, C. D. 2010. A phylogenetic approach to disentangling the role of competition and habitat filtering in community assembly of Neotropical forest birds. Journal of Animal Ecology 79: 1181–1192.

[Other references in SACC Literature]


Gustavo A. Bravo and Robb T. Brumfield, February 2012

Comments from Remsen: “YES. Having gone over the data and informally reviewed the paper, the phylogeny requires removal of these two species from Myrmotherula. Expansion of Thamnomanes to include them would violate the morphological and behavioral themes of the members of that genus. Naming a new genus is the logical solution.”

Comments from Stiles: “YES; the split is well documented and the name Isleria is certainly a fitting recognition of the Islers' contributions to antbird taxonomy.”

Comments from Robbins: “YES. This seems the most reasonable course of action. Nice choice in generic name to recognize the Islers’ many contributions to antbird relationships.”

Comments from Zimmer: “YES. The molecular data clearly dictates that guttata and hauxwelli be removed from Myrmotherula. Although sister to Thamnomanes, guttata and hauxwelli are very different beasts morphologically, vocally, and ecologically. Erection of a new genus is by far the best way to deal with this, and the authors have picked a most appropriate name given the many contributions made by the Islers to our knowledge of the Thamnophilidae.”

Comments from Nores: “YES. The molecular analysis by Bravo et al. (2012) shows clearly that Myrmotherula guttata and M. hauxwelli are not related to the true Myrmotherula and Epinecrophylla, and consequently the erection of a new genus is well justified. The other option in putting them into Thamnomanes seems less appropriate, but this would violate the morphological and behavioral characteristics of the members of that genus.”

Comments from Pacheco: “YES. Uma justa homenagem aos Islers a partir de um split robustamente demonstrado.”

Comments from Jaramillo: “YES. This is the reasonable course of action to take in order to maintain monophyletic genera, and genera that are not exceedingly broad.”