Development of the perithecium and ascospores of Ceriosporopsis halima

Abstract

At first a central core of uninucleate cells with dense contents can be distinguished from an outer layer of uninucleate cells. The former gives rise to the binucleate ascogenous tissue, croziers and asci, but the method by which plasmogamy occurs was not observed. The outer layer forms the central sterile tissue of large vacuolate cells (which is invaded by the growing fertile tissue and ultimately disappears) and the wall of the perithecium. The neck arises from the outer wall layer and is filled with inwardly growing, turgid periphyses which block its cavity until just before the ascospores are extruded. Ceriosporopsis halima Linder and C. cambrensis Wilson are considered to show similar perithecial development and conform to the Diaporthe-type of Luttrell. They can be classified in Halosphaeriaceae, order Sphaeriales, of Muller & Arx. The wall of the mature ascospore consists of three layers. The appendages are formed at each end of the spore by the extrusion of mucilage, still enclosed in the epispore, through pores in the inner wall layers. The whole spore is enclosed in a sheath. After the breakdown of the asci and the extrusion of the spores through the neck, first the sheath disperses in the sea and then the appendages become softened and stretchable. Minor differences in the development of the appendages within the sheath distinguish C. halima, C. cambrensis and C. hamala Hohnk.