Willisornis vidua, NIGRIGULA (SNETHLAGE, 1914)

Quaresma, Tânia Fontes, Cronemberger, Áurea A., Batista, Romina & Aleixo, Alexandre, 2022, Diversification and species limits in scale-backed antbirds (Willisornis: Thamnophilidae), an Amazonian endemic lineage, Zoological Journal of the Linnean Society 196 (4), pp. 1408-1430 : 1421

WILLISORNIS VIDUA NIGRIGULA ( SNETHLAGE, 1914)

Taxonomy

Genetic lineages possessing plumage characteristics described below can be assigned to W. v. nigrigula (type locality: Boim, on the left/western bank of the Tapajós River; Peters, 1951), distributed in the lower Madeira–Tapajós interfluve and between the Tapajós and Xingu rivers in the Brazilian states of Amazonas, Mato Grosso and Pará ( Isler & Whitney, 2011). Plumage attributes: males similar to W. p. gutturalis , with both taxa sharing a conspicuous black throat patch not found in males of any other Willisornis taxa. However, W. v. nigrigula males have ventral and dorsal parts paler grey. Females, on the other hand, are similar to those in W. p. griseiventris , with pale rufous colouring throughout the dorsal region and a missing ‘dark-light lace’ from the back and wings. However, in W. v. nigrigula females, the dorsal colour does not extend to the sides of the head, being limited to the crown, forehead and supercilium. The ventral grey colour extends to the sides of the head, with the throat presenting a pale grey colour.

Genetic differentiation

Specimens sharing the plumage characteristics above belong to two distinct genetic lineages that are completely sorted for their mitochondrial DNA, but less so for the nuclear genes, and which are distributed from the lower east bank of the Madeira to the left bank of the Xingu River (Fig. 1). These lineages replace each other across the Tapajós River and are referred herein as W. v. nigrigula A and W. v. nigrigula B (Fig. 1).

Plumage variation

Specimens of W. v. nigrigula differ with respect to the size of the gular patch. In W. v. nigrigula A (distributed in the northern part of the Tapajós– Madeira interfluve), the black throat patch tends to be slightly smaller and narrower than in W. v. nigrigula B (from the Tapajós–Xingu interfluve). However, some individuals in both groups deviate from this general pattern and, therefore, this phenotypic variation is not exactly congruent with the lineages recovered in molecular analyses.