Variable Antshrike (Thamnophilus caerulescens) [XC348316]
by Marco Cruz from Jardim Melvi, Praia Grande, S\u00e3o Paulo, Brazil (call)
Variable Antshrike (Thamnophilus caerulescens) [XC334811]
by Robson Silva e Silva from Parque Estadual Intervales, SP, Brazil (call)
Subspecies
Thamnophilus caerulescens (Sibley and Monroe 1990, 1993) was provisionally split into Thamnophilus caerulescens and Thamnophilus pernambucensis by Ridgely and Tudor (1994), but this treatment is not followed by the BirdLife Taxonomic Working Group because caerulescens is "exceptionally variable in appearance", which, together with the fact that several taxa of uncertain status are involved, not just pernambucensis (one of them, cearensis, would have to be separated off together with pernambucensis) indicates that a very thorough museum study is called for to help resolve the issues raised, and that this work needs to be supplemented by audio evidence. Specific status is, therefore, not presently adopted by the BirdLife Taxonomic Working Group.
Relationships uncertain. Has been treated as forming a superspecies with Amazonian Antshrike (Thamnophilus amazonicus), but such a relationship considered unlikely. Complex plumage variation and unusual geographical distribution suggest that this species is a prime candidate for systematic study. Other described subspecies seem indistinguishable or have plumage differences that appear to be clinal. Thus, subandinus (northern Peru) synonymized with melanochrous, connectens (east-central Bolivia) with dinellii, albonotatus (east-central Brazil) with nominate, and pernambucensis (north-eastern Brazil) with cearensis. Documentation needed in order to establish whether any parapatry without intergradation exists among subspecies listed.
The following 8 subspecies are recognised:
melanchrous Sclater, PL & Salvin, 1876 - Eastern slope of Andes in Peru (from Amazonas south of R Marañón south to northern Puno).
aspersiventer d'Orbigny & Lafresnaye, 1837 - South-eastern Peru (south-eastern Puno) and west-central Bolivia (northern slope in La Paz, Cochabamba and Santa Cruz).
dinellii von Berlepsch, 1906 - East-central and southern Bolivia on southern and eastern Andean slopes (Santa Cruz south to Tarija), and north-western Argentina (eastern slope from Jujuy south to La Rioja and, at lower elevations, east to Formosa and south to northern Córdoba and Santa Fe).
paraguayensis Hellmayr, 1904 - South-eastern Bolivia (lowlands of Santa Cruz), north-western and north-central Paraguay (west of R Paraguay and, to east, in Concepción, Amambay and San Pedro) and southern Brazil (Mato Grosso do Sul).
gilvigaster Pelzeln, 1868 - North-eastern Argentina (east of R Paraná except Misiones), extreme south-eastern Brazil (eastern Paraná and south-eastern Sío Paulo south to Rio Grande do Sul) and Uruguay.
caerulescens Vieillot, 1816 - South-eastern Paraguay (east of R Paraguay except Concepción, Amambay and San Pedro), extreme northern Argentina (Misiones), and northern part of south-eastern Brazil (Minas Gerais and south-eastern Bahia south to western Paraná, western and north-eastern Sío Paulo and Rio de Janeiro).
ochraceiventer Snethlage, E, 1928 - East-central Brazil (southern Tocantins, Goiás, Distríto Federal, south-central Bahia).
cearensis (Cory, 1919) - North-eastern Brazil (Ceará, Pernambuco, Alagoas).
BirdLife International Species Factsheet