BIOMETRICAL INDICATION OF A SYSTEMATIC-TAXONOMICAL SIGNIFICANCE OF UVIGERINID CHAMBERS

By investigating specimens of Uvigerina grilli, U. semiornata and U. v enusta from the Neogene of the Vienna Basin, and of U. pygmea, the typ e-species of the genus, from the Pliocene of Northern Italy, the syste matic-taxonomical significance of uvigerinid chambers is verified by b iometrical methods using chamber height and breadth. Two basically dif ferent types of chambers are distinguished, confirming the existence o f two species-groups previously observed and established by other work ers: One named after U. semiornata, characterized by large and distinc tly overlapping chambers with somewhat angled basal sutures, a second named after U. peregrina, exhibiting more or less inflated, not explic itly overlapping chambers with straight basal sutures. Uvigerina grill i and U. semiornata are recognized as members of the U. semiornata-gro up, U. pygmea and U. venusta as members of the U. peregrina-group. The findings of this study bear consequences for the traditional systemat ics of uvigerinids from the Vienna Basin, which so far have relied pre dominantly on the ornamentation of tests: For example, Uvigerina grill i cannot be ranked as the parental form of U. venusta any longer, but has to be classified with the U. semiornata-group instead, because of its basically different type of chambers. Moreover, the biometrical re sults of this investigation support the concept of a number of workers , that virtually all uvigerinid species, fossil and recent, can be ass igned to only two lineages by their characteristically different chamb er-types. The actual existence and the postulated strict separation of these two lineages is supported by this study.