Slavicekia gen. nov., a New Member of the Normapolles Complex from Late Cretaceous Sediments of the Czech Republic

Abstract

Premise of research. The Klikov Formation in South Bohemia, Czech Republic, is well known as a rich source of Late Cretaceous mesofossils including numerous angiosperm reproductive structures. In this study, we restudy and reevaluate all flower and fruit specimens from this formation that were earlier referred to the species Vangerowia tricornuta Erw.Knobloch et Mai, and on the basis of a detailed morphological analysis, we describe and establish the new genus Slavicekia and the new species Slavicekia inaequalis. Methodology. Morphological and anatomical investigations of the fossil fruits were carried out using scanning electron microscopy and X-ray micro–computed tomography. Pivotal results. Flowers of Slavicekia exhibit a unique combination of floral characters. Flowers are structurally bisexual and epigynous. The perianth comprises five small tepals arranged in one whorl of two and one whorl of three tepals. The androecium consists of five stamens placed opposite to the tepals (i.e., also the stamens are arranged in two anisomerous whorls). Pollen grains are triangular-oblate and triaperturate. The gynoecium is tricarpellate-syncarpous with an ovary that contains two unequally sized locules, each producing one ovule, but only the one in the larger locule matures into a seed. Conclusions. The type of pollen is characteristic for Normapolles plants, and we therefore propose Slavicekia as a new member of the Normapolles complex in the order Fagales. In addition to the pollen features, other characters, including epigyny, a reduced perianth, and a single seed per fruit, link Slavicekia with the Normapolles complex and the order Fagales. On the basis of a comparison with other Normapolles fossils and extant taxa, we discuss the potential systematic affinities of Slavicekia within core Fagales.