Article: Spermatophyte preovules from the basal Carboniferous of the Avon Gorge, Bristol
Aglosperma avonensis is a new acupulate species of Early Carboniferous preovule from the VI miospore biozone of the Avon Gorge near Bristol. It is closest in morphology to the slightly older Aglosperma quadrapartita from the Taff Gorge near Cardiff, although distinction can be made on the characteristics of the integument, the nucellus and on general size. The possibility that the new preovule represents an ontogenetic stage of A. quadrapartita is discounted. The new species displays characteristics of the nucellar apex not observed in the type species, possessing a distinct pollen chamber and tubular salpinx, most probably evidence of a hydrasperman pollen chamber. The distribution of Aglosperma and other similar preovulate structures indicates that acupulate preovules were perhaps as cosmopolitan as the previously more widely known cupulate forms during this early period of spermatophyte radiation.