Divergence in wing‐whirring, vocalizations and morphology supports species status for the Santa Marta Guan ( Penelope colombiana )

The Band‐tailed Guan Penelope argyrotis is a polytypic species of humid montane forest with three currently recognized subspecies: nominotypic argyrotis in the main Andes of Colombia and in the Andes and northern mountain ranges of Venezuela; albicauda in the Sierra de Perijá in Colombia and Venezuela; and colombiana in the Sierra de Santa Marta, Colombia. Here, we assessed the species limits in P. argyrotis using bioacoustic and morphological data. We found numerous diagnostic external features between the argyrotis (including ssp. argyrotis and albicauda ) and the colombiana groups: argyrotis had dark brown iris, broader, blunter and browner crown feathers, only those on the forehead partially margined with greyish white, bluish facial skin with conspicuous and bright silvery white superciliary and malar stripes, hindneck and mantle less profusely marked with pure white lateral edges, longer wings, less extensive and paler tail tips (cinnamon argyrotis ; dingy buff albicauda ) and dull pinkish tarsi, whereas colombiana had golden ivory iris, slimmer and acuminate crown feathers all margined with greyish white for their entire length, dark grey facial skin with indistinct and subdued ashy greyish superciliary and malar stripes, hindneck and mantle more profusely marked with buffy white lateral edges, shorter wing, more extensive and darker (auburn) tail tips, and brighter red tarsi. The dawn song of argyrotis was a series of shorter, less spaced (faster) and narrower‐band upswept notes without frequency jumps (lacking yodelling quality) whilst in colombiana, it was a longer series with more spaced (slower) and broader‐band upswept notes with obvious frequency jumps (with yodelling quality). The wing‐whirrs of argyrotis had two segments separated by a clear pause, whilst colombiana had a single segment; wing‐whirrs of argyrotis had significantly more notes, were significantly longer in total and net duration, and had a significantly slower gross rate (but not net rate) than those of colombiana . The striking differences between them exceed those typical of taxa currently ranked as species in Penelope and thus support the recognition of two species, the Silver‐eared Guan P. argyrotis (with ssp. argyrotis and albicauda ) and the Santa Marta Guan P. colombiana , separated by ca. 120 km across the dry portion of the Cesar–Ranchería basin. Our work highlights the importance of bioacoustics as a taxonomic tool in guans, and the utility of photo archives and detailed field observations in understanding intertaxon differences in bare parts coloration.