Long-billed Gnatwren (Ramphocaenus melanurus)

Races form at least three groups, all perhaps meriting species rank, but while vocal differences between the first two groups are relatively minor, those distinguishing the third may be greater (but recorded material sparse); further research, including molecular work, required. Races rufiventris and griseodorsalis were, until 1931, considered to represent a separate species and may warrant restoration as such, along with ardeleo and panamanensis; they seldom sing at constant pitch (usually initially rising or falling), while other taxa usually sing at constant pitch, but there is much overlap#R. Races obscurus and sticturus share distinctive morphology (white spots on outer rectrices) and seemingly also voice (but see above), and appear to occur in sympatry or near-sympatry (but are not syntopic) with amazonum and badius#R. Distributional limits of N races and of albiventris uncertain; details listed below are tentative. Fifteen subspecies recognized.