DEVONIAN SPORE ULTRASTRUCTURE - RHABDOSPORITES

The fine structure of in situ Rhabdosporites langii miospores is descr ibed. The trilete spores are characterized by an irregular pseudosaccu s that is conspicuous on the distal surface of the grain; ornamentatio n consists of narrow coni. The central body of the spore is constructe d of superimposed lamellae, each up to 50 nm thick. Pseudosaccus forma tion occurs as a result of a separation of the outer one third of the sporoderm of the central body. As development continues small perforat ions are formed in the pseudosaccus wall where lamellae separate. The development of the saccus, protosaccus and pseudosaccus is compared, a nd the biological significance of camerate grains discussed.