Morphological analysis of air sacs in red-winged tinamou (<i>Rhynchotus rufescens</i> Temminck, 1815)

Anatomical descriptions of partridges' air sacs of the species Rhynchotus rufescens are scarce. This study aimed to evaluate the air sacs of this species. Ten cadaveric specimens of adult partridges, approximately 1 year old, were collected, and latex perfusion was used to solidify the material. The cervical air sac of a red-winged tinamou is smaller and has a more irregular conformation than other air sacs. The thoracic air sacs are symmetrical, and the cranial thoracic air sacs are smaller than the caudal ones. The abdominal air sacs are asymmetrical, and the largest ones extend themselves to the cloaca. Only one clavicular air sac was found, with three subdivisions: right, left, and medial. Additionally, right and left extrathoracic portions were found, passing under the clavicle. In one of the animals, the latex-filled humeri were found, and in three other ribs, vertebral diverticula were present. There is no clear relationship between taxonomy and biology versus the quantity and conformation of air sacs, because different animals with taxonomic proximity present differences. This study enhances species-specific anatomical knowledge of this species of partridge.