Re-examination of Teladorsagia hamata (Mönnig, 1932) Durette-Desset, 1989 reported from grey rhebuck, Pelea capreolus (Forster, 1790) proved it to be a new species of Ostertagi Ransom, 1907. The new species, for which the name Ostertagia triquetra n. sp. is proposed, differs from Teladorsagia hamata in the configuration of the bursal rays (2-1-2 in the former, 2-2-1 in the latter), and in that the interno-dorsal branch of the spicules bears a process that is triangular and convex in the new species, but concave and shaped like an ice-cream scoop in Teladorsagia hamata. Ostertagia triquetra has so far been found only in grey rhebuck in the Eastern Cape Province while Teladorsagia hamata was recorded from springbok, Antidorcas marsupialis (Zimmerman, 1780) and gemsbok, Oryx gazella (Unnaeus, 1758) in the western part of the country.