I don't know if this has been mentioned here before, but xeno-canto has recordings of three undescribed Herpsilochmus antwrens.
'Inambari-Tambopata' Antwren (a photo of which currently graces the xeno-canto americas homepage)
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.99
'Madeira-Purus' Antwren
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.85
'Aripuana-Ji-parana' Antwren
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.95
'Inambari-Tambopata' Antwren (a photo of which currently graces the xeno-canto americas homepage)
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.99
'Madeira-Purus' Antwren
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.85
'Aripuana-Ji-parana' Antwren
http://www.xeno-canto.org/XCspeciesprofiles.php?species_nr2=2090.95