Taxonomic relationships in Terebratulina (Brachiopoda) established by multivariate morphometrics

Three morphologically-similar species of Terebratulina can be discriminated by means of a battery of multivariate statistical techniques applied to seven shell traits on 12 sample sets. T. retusa and T. unguicula are most alike morphometrically, whereas T. septentrionalis is equally distant from both of those species. In the light of existing molecular data, the similarity between T. retusa and T. unguicula can be interpreted as an example of symplesiomorphy. The results of the morphometric analyses also suggest that T. unguicula is probably a heterogeneous species, and that T. unguicula rotundata stands up well as a separate taxonomic entity. The data also revealed that one museum-curated sample of T. retusa has been misidentified as T. septentrionalis.