New evidence on the previously unknown gynoecium of Araripia florifera (Araripiaceae, fam. nov.), a magnoliid angiosperm from the Lower Cretaceous (Aptian) of the Crato Konservat-Lagerstätte (Araripe Basin), northeastern Brazil

Abstract

The angiosperm Araripia florifera was originally described based on a fossil specimen including a few lobed leaves and floral buds. Although nothing was known of the internal structure of the flowers, based on the external similarity of the flower buds, it was compared with Calycanthaceae (Laurales). A new fossil from the type locality provides the first morphological evidence for the gynoecium of A. florifera. An androecium was not found, but new evidence is still needed to determine whether the flowers are unisexual. The gynoecium of this fossil species is syncarpous or monomerous, the ovary is superior, globose and distinctly stipitate, and the style is elongated and relatively thick. This new floral information disagrees with suggestions that Araripia belonged to the family Calycanthaceae, because this extant family is characterized by perigynous flowers, with apocarpous gynoecium and ovaries that are never stipitate. We also question the leaf arrangement, originally proposed as opposite, but alternate in this new fossil. We provide a phylogenetic hypothesis combining morphological and DNA sequence data using Bayesian inference. Our phylogenetic analyses indicate that A. florifera is more likely an extinct lineage of Laurales, and is hereby placed in its own family Araripiaceae.