Systematic updates of the agglutinated foraminiferal genus Colominella Popescu, 1998: insights from sectioned specimens

Abstract

Abstract The occurrence of agglutinated foraminiferal specimens belonging to the Badenian (middle Miocene) genus Colominella Popescu, 1998 was recently documented for the first time in a lower Pliocene succession of the western Mediterranean area. Direct comparisons with topotype specimens of Colominella paalzowi (Cushman 1936), sampled in the Badenian type section of Lăpugiu de Sus (Transylvania), show that the Pliocene individuals from the western Mediterranean morphologically resemble the type species C. paalzowi, but they also differ in possessing a longer biserial chamber arrangement with a higher number of internal chamber partitions, in lacking a clear early triserial stage and in having a more complex microstructure of the agglutinated wall, thereby supporting the idea that the Pliocene Mediterranean specimens represent a new, more highly evolved species. The fact that the Pliocene individuals from the Mediterranean appear to be more evolved with respect to the Badenian specimens from Paratethys represents an interesting evolutionary development of the genus Colominella that also permits the known stratigraphical and geographical range of the genus, previously limited to the middle Miocene (Badenian) of the Paratethys, to be extended.