Paralygodium vancouverensis sp. nov. (Schizaeaceae): Additional Evidence for Filicalean Diversity in the Paleogene of North America

Several fertile pinnules with abaxially borne sporangia have been discovered in calcareous marine nodules from the Middle or Late Eocene Appian Way locality on the east coast of Vancouver Island, British Columbia, Canada. Fertile pinnules are attached in groups of two or three. They are deeply lobed, with each lobe rolled toward the abaxial surface and the entire pinnule rolled toward the abaxial surface to form an irregularly globose structure. Sporangia occur abaxially and form two rows over the entire surface of each pinnule lobe. The midrib of each pinnule lobe is thickened, forming a receptacle from which broadly attached sporangia and numerous paraphyses diverge. As is characteristic of many schizaeaceous ferns, sporangia of the fossil are flask shaped with a short stalk and have a uniseriate, transverse annulus at the apex. Spores are tetrahedral and trilete, like those of the type species for the extinct genus Paralygodium. The new specimens are described as Paralygodium vancouverensis sp. nov. and are compared to both living genera of schizaeaceous ferns and the extinct species Paralygodium yezoense and Anemia poolensis. The unique combination of characters displayed by each of the fossil species reveals the presence of several extinct schizaeaceous lineages and supports interpretations that the diversity of Schizaeaceae s.l. was greater during the Cretaceous and Paleogene than it is today.