Wedge-billed Woodcreeper (Glyphorynchus spirurus) - HBW 8, p. 407

Taxonomy: Neops spirurus Vieillot, 1819, South America = “Cayenne”.
An exceptionally small and morphologically distinctive woodcreeper that, despite appearing similar to a Xenops (Furnariidae), is allied with woodcreepers on the basis of both anatomy and pterylosis.Possibility that more than one species is involved suggested by existence of two markedly different song types, combined with several well-differentiated races; however, molecular data suggest gene flow between some neighbouring, morphologically distinctive subspecies. Significant genetic distances have been documented between some populations, but geographical pattern difficult to explain; genetic differentiation inconsistent with subspecific taxonomy, but may better support geographical patterns defined by vocalizations. All birds in C Brazil E from R Tapajós tentatively placed with paraensis, but those from E bank of R Xingu said to be intermediate between that and inornatus; recent records from NE Bolivia (Santa Cruz) also probably attributable to latter race; more work needed to clarify limits of races. Characters of rufigularis possibly lie within range of individual variation of castelnaudii, a highly variable taxon. Described race sublestus (S Central America) synonymized with individually variable pectoralis (birds from Nicaragua and Costa Rica intermediate between the two), which intergrades with pallidulus in E Panama (Caribbean slope in SE Colón). Thirteen subspecies recognized.