Morphological changes during the ontogeny of Velapertina indigena (Foraminifera) from the Transylvanian Basin (Romania)

Species Velapertina indigena (Luczkowska, 1955) represents common Upper Badenian planktonic foraminifera in the Western Carpathians region. Correct taxonomic determination is often precluded by the complicated ontogenetic evolution resulted into several distinguished morphological stages. In this study the inner shell structures were observed by using tomographic microscope to identify five ontogenetic stages (sensu Brummer). General morphological features of the shell, such as the chamber shape and number, the aperture position and character, the wall texture, and the chambers coiling direction were documented for each stage. The reconstructed ontogenetic model, composed of five ontogenetic stages, was correlated with the 'five stage concept' of Globigerinoides sacculifer. Our study shows potential of the tomographic microscope visualization in improvement of the correct taxonomic classification of non-adult individuals as well as the foraminifera trophic mechanisms interpretation. (authors)