A New Fossil of Cystodium (Cystodiaceae) from the mid-Cretaceous Myanmar amber

The only known fossil of Cystodium (Cystodiaceae) is C. sorbifolioides from mid-Cretaceous Myanmar amber. Here we describe a new fossil species of Cystodium, C. parasorbifolium, also from amber collected in Myanmar. This new species belongs to Cystodium based on pinnate fertile lamina segments, terminal sori protected by a reflexed lobe of the lamina (outer or false indusium), free veins, vertical annuli interrupted at the stalk, trilete spores, and striate perines. It differs from C. sorbifolioides by reflexed ovate-conical indusia and spores with clear striate perines. This new fossil species suggests that Cystodium was more diverse in the forests of Myanmar during the Cretaceous.