Diversification and species limits in scale-backed antbirds (Willisornis: Thamnophilidae), an Amazonian endemic lineage Author Quaresma, Tânia Fontes Author Cronemberger, Áurea A. Author Batista, Romina Author Aleixo, Alexandre text Zoological Journal of the Linnean Society 2022 2022-04-20 196 4 1408 1430 http://dx.doi.org/10.1093/zoolinnean/zlac011 journal article 10.1093/zoolinnean/zlac011 0024-4082 1719CE06-0D0E-4E8E-94E8-37AC811AED10 WILLISORNIS POECILINOTUS LEPIDONOTA ( SCLATER & SALVIN, 1880 ) Taxonomy Genetic lineages with plumage characteristics described below are apparently related to W. p. lepidonota ( type locality: Sarayacu, Pastaza , Ecuador ; Peters, 1951 ; Isler & Whitney, 2011 ), distributed in southern Colombia , eastern Ecuador and eastern Peru ( Isler & Whitney, 2011 ; Gill et al. , 2022 ). Plumage attributes Due to logistical constrains (see Discussion), we analysed the plumage of only one female specimen within the known range of W. p. lepidonota . This particular specimen presents an intense rufous colour above, but with slightly paler underparts, resembling females of W. p. gutturalis . In comparison with females of W. p. duidae , the rufous colour of the examined specimen is noticeably less intense. The ‘lace’ is present and is similar to those in males (i.e. in black-white colour; as in Zimmer et al. , 2020 ). Tail rufous, with terminal and intermediate white dots. Genetic differentiation The female plumage characteristics described above belong to a specimen (MPEG 54179) obtained from a locality ( Peru , Amazonas, Rio Comaina) within the range of W. p. lepidonota lineage A (Fig. 1). Along with W. p. lepidonota B (which apparently replaces W. p. lepidonota A across the Huallaga River), these lineages are completely sorted for their mtDNA, but less so for the nuclear genes (Fig. 1). Together, they occupy the foothills of the Andes from eastern Ecuador to central Peru eastward to the Ucayali and possibly the Napo rivers, respectively, in southern and northern Amazonia (Supporting Information, Table S1 ; Fig. 1). Plumage variation Because only one female specimen was examined, no plumage variation within and between W. p. lepidonota A and W. p. lepidonota B could be assessed. As discussed above, four Peruvian specimens sequenced by us from the north bank of the Amazon and Napo rivers (and thought previously to belong W. p. lepidonota ; Isler & Whitney, 2011 ) grouped, in fact, with W. p. duidae C, suggesting either introgression or lack of consistent plumage diagnoses between these taxa.