Myrmotherula menetriesii

Chesser, R. Terry, Isler, Morton L., Santana, Antonita, Latch, Emily K., Stryjewski, Katherine Faust, Reed, Jennifer, Naka, Luciano N., Fleischer, Robert C. & Aleixo, Alexandre, 2025, Comparative phylogeographic patterns in three pan-Amazonian antwren lineages (Aves: Passeriformes: Thamnophilidae: Myrmotherula and Isleria), Zootaxa 5722 (1), pp. 1-44 : 8

Gray Antwren M. menetriesii

Analyses for M. menetriesii distinguished five main clades, each separated by at least 2.3% uncorrected sequence divergence from the others ( Table 1; Fig. 6 ). These clades correspond to the five subspecies of menetriesii ( berlepschi, cinereiventris , pallida, and omissa , in addition to menetriesii ), except for individuals from the lower Madeira-Tapajós interfluvium ( Fig. 7 ). The upper Amazon and Marañón separate pallida from menetriesii and the lower Negro and the Branco separate the southeastern distributional limit of pallida from the southwestern limit of cinereiventris . North of this, in extreme northern Brazil and in Venezuela, cinereiventris occurs only east of landscape features such as the Roraima-Rupununi savannas and the Gran Sabana. Samples of berlepschi are located mainly in extreme southern Amazonia east of the Madeira headwaters, with one sample occurring as far east as Nova Mutum, in the headwaters of the Juruena, a tributary of the Tapajós. Samples of omissa , which is known to occur from east of the lower Tapajós south into its headwaters, and east beyond the Tocantins (e.g., Peters 1951; Dickinson & Christidis 2014), were documented additionally to the west of the Tapajós ( Fig. 7 ). The two individuals of omissa from west of the Tapajós, from Nova Canaã and São Martins, form a subclade 1.6% divergent from all samples from the right bank and other samples to the south and east. Subspecies pallida consists of two subclades separated by the Napo, which differ by 0.9%. Several other clades show within-clade diversity, but such variation is not geographically structured. For example, the two northernmost samples of berlepschi, collected from the same locality on the Rio Ji-Paraná, differ by 1.3%. Bootstrap support for the five main clades, as well as for the subclades within omissa and pallida, was uniformly strong: posterior probabilities were all 1.00 and bootstrap values were 91–100%. Relationships among clades were strongly supported except for the sister relationship between omissa and pallida/ cinereiventris (0.71 posterior probability and a 52% bootstrap value). The deepest split within the tree was 5.0% uncorrected divergence, separating menetriesii and berlepschi from the other main clades. The divergence between omissa and cinereiventris , across the lower Amazon, was also substantial at 4.9% uncorrected divergence.

Figures

FIGURE 6. Maximum clade credibility tree for Myrmotherula menetriesii from the BEAST (Bouckaert et al. 2014) analysis. Individuals are color-coded by main clades but also identified by subspecies and subclade. Note that the two individuals from the northern part of the described range of berlepschi group with omissa as omissa-W; examination of specimens from this area confirms that by phenotype they are omissa rather than berlepschi (Isler et al. 2025). Numbers above branches indicate posterior probabilities and ML bootstrap support values at the corresponding nodes. Arrows at nodes and corresponding text indicate rivers that separate clades united by the nodes.

FIGURE 7. Map showing the distributions of main clades and subclades of Myrmotherula menetriesii. Main clades are colorcoded to match FIGURE 6; subclades within omissa and pallida are separated by dashed lines along the Tapajós and the Napo, respectively. Solid dots = tissue locations; heavy lines surround geographic ranges as confirmed by the molecular analysis. Refer to FIGURE 2 for names of locations of tissue samples. Base map layers sourced from Esri (Redlands, California).