Sclateria

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 : 485-486

Sclateria clade

Phylogenetic relationships.— Sclateria naevia (Gmelin) is sister to species currently placed in the genus Schistocichla , among which Myrmeciza hyperythra (Sclater) is nested ( Figs. 1 and 2 ). In the following morphological analysis, data for Sclateria naevia , Myrmeciza hyperythra , and Schistocichla caurensis (Hellmayr) are separated because of their larger size, but given their similarity, the plumage and morphometrics of Schistocichla leucostigma Pelzeln, S. saturata (Salvin), S. humaythae (Hellmayr) , S. brunneiceps (Zimmer) , S. rufifacies (Hellmayr) , and S. schistacea (Sclater) are combined as the schistacea group. Until recently (Isler et al. 2007) leucostigma , humaythae , brunneiceps , and rufifacies were considered conspecific.

Biogeography. —Together leucostigma , humaythae , brunneiceps , and rufifacies cover much of Amazonia along with naevia with which they are sympatric. Ranges of schistacea and hyperythra are limited to western Amazonia where they are sympatric with subplumbea and naevia , and caurensis is restricted to the tepuis region.

Plumage.—Males of all species are gray with white wing covert spots; hyperythra has a pale blue periorbital skin patch and naevia a whitish supercilium (variable in intensity) and underparts variably streaked white or extensively white. Females of the schistacea group and caurensis are reddish brown (paler below) with cinnamon tinged wing spots and head variably gray. The underparts of females of hyperythra are similar, but their upperparts are gray, and they have white wing spots and periorbital skin patches like the males. Females of naevia have a supercilium and underparts pattern similar to that of the males, but their upperparts are grayish-brown.

Morphometrics.—The size ( Table 2 ) and proportions ( Table 3) of naevia are similar to those of the schistacea group, but its long slender bill is unique among the Pyriglenini. Except for tail length, hyperythra and caurensis are similar to one another in measurements and proportions, and their proportions are similar to the smaller schistacea group.

Loudsongs.—All species deliver long trills except for schistacea , whose loudsong is a short countable series of clear notes, and caurensis , whose loudsong is a slightly longer countable series of buzzy notes.

Habitat.—The schistacea group inhabits evergreen terra firme forest in lowlands and foothills. Others in the clade occupy more specialized habitats: naevia is found in seasonally flooded forest and sluggish streams in terra firme; hyperythra in seasonally flooded and transitional forests; and caurensis on boulder-strewn tepui slopes.

Foraging behavior.—All species forage on the ground and on low substrates mostly <1 m, hop deliberately, rummage in leaf piles on the ground, and pick prey off low substrates. Specialized foraging behavior includes naevia picking prey off water and caurensis probing in boulder mosses and litter.

Tail and wing movements.—All species except naevia flick their tails up and drop them to ca 30° below horizontal; naevia jerks its tail from side to side. In an earlier publication (Zimmer & Isler 2003) hyperythra was said to pound its tail downward, but video documentation (K. J. Zimmer, pers. comm.) shows that its tail movements are the same as those of other species in the group except naevia .

Nest architecture.—Few nests are known for species in this clade. Conflicting accounts for leucostigma include an open cup (Belcher & Smooker 1936; Greeney et al. 2013) and a nest under a log (O. Tostain pers. comm.). The only nest reported for naevia was an open cup over a stream (David & Londoño 2011). Two nests described for hyperythra were open cups, one attached to a spiny palm and the other to ferns (Londoño 2003).

Discussion.—The first issue is whether to maintain Sclateria as a monotypic genus. Its sister relationship with the rest of the clade is well supported in the molecular analysis. Its maintenance as a monophyletic genus is buttressed by plumage distinctions and bill morphology unique among the Pyriglenini. Differences in tail movements between Sclateria and the remaining species in the clade strongly indicate they should not be considered congeneric, a position supported by the specialized foraging behavior of Sclateria .

The second issue is whether to place in the same genus three subsequent clades consisting of schistacea / saturata , hyperythra , and rufifacies / brunneiceps / leucostigma / humaythae and presumably caurensis . The principal consideration is that hyperythra is nested in the phylogenetic tree between two clades of species currently placed in Schistocichla , some of which are similar morphologically and have been considered conspecific. The pale blue periorbital skin of hyperythra occurs in multiple thamnophilid clades and should not necessitate generic distinction. Otherwise, outside of the more extensive gray upperparts of the female, hyperythra is a large version of the Schistocichla species morphologically. Behavioral characteristics of hyperythra are also consistent with those of Schistocichla species although more needs to be known of nest architecture. The evidence points to placing Schistocichla species and hyperythra in the same genus.

Taxonomic Recommendations.—We recommend that Sclateria be maintained as a monotypic genus and that hyperythra and species currently placed in Schistocichla be merged. Myrmelastes Sclater 1858 a has priority for this reconstituted genus. Thus, Schistocichla becomes a junior synonym of Myrmelastes .

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).