Isleria

Isler, Morton L., Chesser, R. Terry, Stryjewski, Katherine Faust & Whitney, Bret M., 2025, Systematics of three pan-Amazonian antwren lineages (Aves: Passeriformes: Thamnophilidae: Myrmotherula and Isleria), Zootaxa 5722 (1), pp. 45-78 : 69-70

Isleria h. hauxwelli

Includes the population designated hauxwelli- W in the analysis.

Diagnosis. Song differs from those of other subspecies of I. hauxwelli by the frequency modulation of individual notes. Plumage differs from that of I. h. hellmayri by having a white interscapular patch.

Distribution. Bounded on the north by the Rio Japurá, Brazil, from its mouth north to the vicinity of Rio Guainía, Colombia, thence west to near the base of the Andes in Meta, Colombia; on the west by the Andes from Meta, Colombia, south to the vicinity of the Rio Cushabatay, Peru; and on the east by the Rio Ucayali from the mouth of the Rio Cushabatay north.

Remarks. Although initially the type locality of nominate hauxwelli was identified simply as “e. Peru ” ( Sclater 1857), a subsequent publication by the same author ( Sclater 1858) pinpointed the locality as Chamicuros, which is south of the Río Marañón and west of the Río Ucayali. The frequency modulation distinguishing Songs recorded in this region was characteristic of Songs recorded north of the Rio Marañón, the region currently ascribed to I. h. suffusa. Furthermore, no morphological differences were found between populations north and south of the Rio Marañón. Consequently, suffusa is considered a synonym of the nominate form, a conclusion supported by the phylogeny. The nominate subspecies differs by 2.5–3.0% in mtDNA from other subspecies of I. hauxwelli .