Myrmeciza longipes

Isler, Morton L., Bravo, Gustavo A. & Brumfield, Robb T., 2013, Taxonomic revision of Myrmeciza (Aves: Passeriformes: Thamnophilidae) into 12 genera based on phylogenetic, morphological, behavioral, and ecological data, Zootaxa 3717 (4), pp. 469-497 : 489-490

longipes clade

Phylogenetic relationships.—The phylogeny located Myrmeciza longipes (hereafter longipes ) at the base of a large clade with the Myrmoborus clade and the Gymnocichla clade as subsequent sisters ( Figs. 1 and 2 ). The Myrmoborus clade consists of Percnostola lophotes Hellmayr and Seilern and four Myrmoborus species including M. melanurus (Sclater and Salvin) , M. myotherinus (Spix) , M. leucophrys (Tschudi) , and M. lugubris (Cabanis) . Data for the morphologically similar Myrmoborus species are combined as the myotherinus group. Percnostola lophotes is identified by its specific name. The Gymnocichla clade includes Gymnocichla nudiceps (Cassin) (hereafter nudiceps ); the genus Pyriglena including P. leuconota (Spix) , P. leucoptera (Vieillot) , and presumably (Maldonado-Coelho 2012) P. a t r a (Swainson); the genus Percnostola including P. rufifrons (Gmelin) and P. arenarum Isler, Alvarez, Isler , and Whitney; and two clades currently placed in Myrmeciza —the immaculata clade including M. immaculata (Lafresnaye) , M. zeledoni Ridgway , and M. fortis (Sclater and Salvin) , and the melanoceps clade including M. melanoceps (Spix) and M. goeldii (Snethlage) . Relationships among Percnostola , the immaculata clade, and the melanoceps clade are not resolved with high support. Although not included in our analysis, Rhopornis ardesiacus (Wied) is also a member of the longipes clade (Bravo et al. in prep.).

Biogeography. —Most species are Amazonian in distribution. However, longipes is patchily distributed west of the Andes and east of the Andes north of the Amazon, nudiceps and immaculata are trans-Andean, and the ranges of Pyriglena species extend to both Pacific slope of the Andes and the Atlantic coast of Brazil south to northern Argentina. Most species have limited geographic ranges and are allopatric within clades except myotherinus and leucophrys whose ranges are extensive and overlap most other cis-Andean species. Also, longipes is sympatric only with leucophrys in the Guianan region; fortis is sympatric with the melanoceps clade; and immaculata is only narrowly sympatric with nudiceps , as are Pyriglena and Percnostola species with fortis , melanoceps , and goeldii .

Plumage.— Pyriglena , Percnostola , and Myrmoboru s species exhibit distinctive plumage features. Males of all species are black, gray, and white although plumages of some Pyriglena subspecies also include dark chestnut. Males of Pyriglena species have bright red eyes and white interscapular patches. The gray males of the two Percnostola species have distinctive black throats and dark crowns. The gray males of most species in the Myrmoborus clade have a distinctive face and throat patch edged with a white or pale gray superciliary although those of melanurus and lophotes are altogether black or blackish. Females are primarily brown with the following features: Pyriglena species have blackish tails; females of Percnostola species are gray or cinnamon-gray above; most females in the Myrmoborus clade have black or blackish lores and ear-coverts forming a distinctive patch although these are lacking in one lugubris subspecies and lophotes . The distinct plumage of longipes is distinguished by a number of characters including the rufous upperparts of males and the black subapical spots on wing coverts of females and most male subspecies. Males of nudiceps and the immaculata and melanoceps clades are black or blackish with bare bluish periorbital patches (extending to the forecrown in nudiceps ); the presence of white patches differs among species except that immaculata and fortis share mostly concealed white patch at the bend of wing. Females of nudiceps and the immaculata and melanoceps clades are yellowish-brown to reddishbrown with bare bluish periorbital patches and pale wing covert edges (variable), the presence and extent of black or gray differing among species.

Morphometrics.—The most notable differences in measurements are the large sizes of species in the immaculata and melanoceps clades ( Table 2 ). However, these two clades differ in opposing directions in wing and tail lengths, leading to a large difference in tail/wing ratio ( Table 3). Other noteworthy differences in size involve the relatively short bills and long tails of Pyriglena species which result in significant differences in bill length/total length and tail length/wing length ratios with the myotherinus clade, nudiceps , Percnostola species, and the melanoceps clade.`

Loudsongs.—Loudsongs of all species are structurally similar, consisting of a 2–4 second series of similar notes (typically an inverted V or U shape, less often down-slurred) that are repeated in a regular pattern (only species in the immaculata clade show a slight shift in pattern).

Habitat.—The most distinct types of habitat are occupied by longipes which is found in semideciduous and gallery forest, second growth woodland, and shrubby borders. Other species principally occur in evergreen forests, although some Pyriglena leuconota subspecies occupy deciduous forests. Nearly all species in the longipes clade show a predilection for dense tangles and thickets, especially in forest openings and borders. Specialties include water-related habitats for some Myrmoborus species, sandy soil forest for Percnostola species, and floodplain and transitional forest for the melanoceps clade and lophotes .

Foraging behavior.—All species forage primarily on the ground and on low substrates mostly within 1–2 m of the ground. All species, except perhaps for lophotes and arenarum , follow army ant swarms to some extent. Most are considered “regular” ant-followers, and fortis is considered an obligate follower.

Tail and wing movements.—All species ( arenarum unknown) pound the tail downward and slowly raise it to horizontal or slightly higher.

Nest architecture.—Except for longipes all species ( arenarum unknown) build domed or partially domed nests atop leaf litter on the ground or to 1 m off the ground among fallen limbs or leaf rachides of understory palms (recent additions: Greeney et al. 2004, Lebbin et al. 2007). Myrmeciza longipes builds an open cup just off the ground; said to be placed on supports rather than slung from them.

Discussion.—Consistency of behavioral characteristics, including loudsong structure, tail and wing movements, and foraging behavior, reinforces the molecular finding of common ancestry for species in the longipes clade. An exception is Myrmeciza longipes which differs from other species in the clade in its nest architecture and habitat preferences. Existing genera within the group, Gymnocichla , Myrmoborus , Pyriglena and Percnostola , have, however, long been recognized as distinct in plumage and morphometrics from each other and from longipes , and placing them in a single genus is clearly inappropriate. This leaves questions of lophotes and the immaculata and melanoceps clades. Regarding lophotes , the phylogeny places it within Myrmoborus , and its plumage resemblance to Myrmoborus melanurus (not noted previously in the literature) became obvious after the genetic study showed that they are sisters. The morphologically similar immaculata and melanoceps clades form a polytomy with Percnostola ( Figs. 1 and 2 ) and, therefore, cannot be placed in the same genus. The two clades differ principally in tail length and wing length and consequently in wing/tail proportions. Given the choice of uniting the immaculata and melanoceps clades with the morphologically dissimilar Percnostola or recommending that they be placed in three genera, the latter course is most consistent with previous generic decisions in the Thamnophilidae , such as the purely morphological basis for the maintenance of Gymnocichla and Pyriglena .

Taxonomic Recommendations.—We recommend that Myrmeciza longipes be maintained in a monotypic genus, that Gymnocichla , Myrmoborus , Pyriglena , and Percnostola be maintained as genera, and that Percnostola lophotes be transferred to the genus Myrmoborus . We also recommend that species in the immaculata and melanoceps clades be considered distinct from the foregoing and that they be placed in different genera given their uncertain phylogenetic relationship and the morphometric characters that distinguish them.

Figures

FIGURE 1. Maximum-likelihood tree of a subset of the Thamnophilinae, showing that Myrmeciza is polyphyletic (species names in these clades are emboldened). Members of Myrmeciza are placed in eight different well-supported clades in the Microrhopiini, Pithyini, and Pyriglenini. The color of the circles at nodes indicates bootstrap support values,> 70 % (black), 50 - 70 % (gray), <50 % (white).

FIGURE 2. Bayesian consensus tree of a subset of the Thamnophilinae, showing that Myrmeciza is polyphyletic (species names in these clades are emboldened). Members of Myrmeciza are placed in eight different well-supported clades in the Microrhopiini, Pithyini, and Pyriglenini. The color of the circles at nodes indicates posterior probability support,> 0.95 (black), 0.95 – 0.75 (gray), <0.75 (white).