Although a number of brachiopod genera have been defined mainly from their internal structures, the fixity of those structures has rarely been investigated. Variability of the rather simple loops of two New Caledonian species of the Recent genus Stenosarina (Terebratulida), one species having a variant with endemic morphology, provides insight into the relationship between the two species. Procrustes methods based on landmarks are used. Intra-population variability is found to be of the same order of magnitude as inter-population variability. Moreover, the morphological distance between the endemic variant and the other specimens is greater than the distance between the two species of Stenosarina. The study also identifies a morphocline between the three forms of Stenosarina under study.