Preliminary observations on differences of scale morphology at various stages in the life cycle of ‘Apistonema-Syracosphaera’ Sensuvon Stosch

A preliminary study of the fine structure of various stages in the life cycle of von Stosch's solate of ‘Syracosphaera carterae’ has been made by means of sections and whole mounts. Protoplast structure appears to be similar throughout the cycle. However, the Apistonema thallus possesses a cell wall composed of numerous layers of closely adpressed rimless unmineralised scales. Two types of asexual swarmers are shown to be covered with one or two layers of somewhat similar scales. One type of swarmer possesses a short haptonema which is covered with small scales. In addition the coccolith-bearing stages are shown to be identical with Hymenomonas carterae sensu Manton and Peterfi (1969) and this isolate has therefore been transferred to H. carterae.