The redescription of Serratospiculum tendo is based on specimens taken from 4 female and 6 male peregrine falcons (Falco peregrinus Tunstall). This redescription was necessary since previous morphological characterizations were only based on single nematodes, and important details such as the position of the excretory pore in males and females, description of the female reproductive system, and the size of the posterior caudal disc of males were not given. Serratospiculum tendo differs from its 2 congeners (Serratospiculum seurati and Serratospiculum guttatum) by a longer body length of males and females (113–166 and 293–340 mm, respectively) and longer right and left spicules (452–531 and 1,104–1,341 µm, respectively). In comparison, the body length of male and female specimens of S. seurati is 30–79 mm and 165–220 mm, respectively, and the spicules of the males measured 312–415 and 674–887 µm, respectively. The absence of cuticular bosses in S. tendo and S. seurati is a criterion to differentiate these species from S. guttatum.