Comparative morphometrics for species discrimination and analysis in the tabulate coral Catenipora from Baltoscandia

Transverse thin-section images of 12 species of Catenipora from the Ordovician and Silurian of Baltoscandia are analyzed in detail by a comparison of multivariate and two-dimensional geometric morphometrics. The corallites are described by 17 quantitative and qualitative morphological characters, and by 28 landmarks and centroid size. The statistical methods confirm that C. distans, C. elegans, C. exilis, C. maxima, C. obliqua, C. quadrata, C. rubraeformis, C. tapaensis, C. tractabilis, C. vespertina, and C. wrighti are valid species, and that C. monstruosa is a synonym of C. maxima. Geometric morphometrics is shown to be more effective than multivariate analysis in the discrimination of species. Relative warp analysis and thin-plate spline deformation grids are especially useful for characterizing corallite shape. Possible evolutionary relations and trends recognized among the species suggest that diversification in Catenipora may have involved niche partitioning with differences in the polyps size and shape. This study provides methods on evaluating the type specimens through individual corallites.