Cunninghamia beardii sp. nov. (Cupressaceae: Cunninghamioideae), Anatomically Preserved Pollen Cones from the Eocene of Vancouver Island, British Columbia, Canada
Abstract
Premise of research. A large pollen cone cluster attached to a cunninghamioid twig and surrounded by leaves has been identified from Eocene calcium carbonate marine concretions from the Appian Way locality on Vancouver Island, British Columbia, Canada. The cluster preserves 18 cones but probably bore at least 24 pollen cones based on cone placement in the cluster.
Methodology. Specimens were studied using the cellulose acetate peel technique, and reconstructions were made with ImageJ visualization software. Pollen was examined using SEM.
Pivotal results. Cones are helically arranged around the tip of an ultimate leafy branch that terminates in scale leaves, each showing a central resin canal. Vegetative leaves on the twig are amphistomatic, showing typical cunninghamioid anatomy, with a large central resin canal abaxial to the vascular bundle, an elongate zone of transfusion tissue, a nonplicate mesophyll, and a hypodermis three to four cells thick. Each pollen cone is produced in the axil of a bract and has three scale leaves surrounding the base of the cone axis. Individual pollen cones have helically arranged microsporophylls, each with three elongate abaxial pollen sacs. While the cones are immature, pollen sacs with pollen are present in several cones. The exine is scabrate, with numerous orbicules, and no papilla is evident.
Conclusions. This cluster provides the first detailed anatomically preserved fossil evidence for the pollen cones of Cunninghamia. It shows a large number of similarities to the pollen cone clusters of extant Cunninghamia lanceolata and Cunninghamia konishii and the Late Cretaceous Cunninghamia taylorii, strengthening hypotheses for a basal position of cunninghamioids within the Cupressaceae and further demonstrating that some characters of Cunninghamia have remained relatively unchanged since at least the mid-Cretaceous.