Ultrastructure of ascus and ascospore appendages of the mangrove fungus Halosarpheia ratnagiriensis (Halosphaeriales, Ascomycota)

Halosarpheia Kohlm. et E. Kohlm is a genus of eighteen species, all of which have septate ascospores with unfurling polar appendages. Asci and ascospores of Halosarpheia ratnagiriensis Patil et Borse were examined at the scanning (including freeze-fracture) and transmission electron microscope levels. The ascus wall has two well-defined layers and the apical apparatus comprises a refractive, electron-dense, lens-shaped disk embedded within a less electron-dense thickening. The ascospore wall comprises an episporium and a bipartite mesosporium, and the appendages are formed by extrusion of mucilaginous material through an episporial pore field. Ascospore appendage ontogeny is compared with other genera with unfurling polar appendages: Cataractispora, Diluviocola, Tunicatispora, Tirispora, and Halosarpheia aquadulcis Hsieh, H.S. Chang et E.B.G. Jones and Halosarpheia heteroguttulata S.W. Wong, K.D. Hyde et E.B.G. Jones.Key Words: ascospore appendage ontogeny, marine ascomycetes, unfurling polar appendages, ultrastructure.

Mucilage sheaths of spores of red algae

If newly released spores of red algae are placed in a suspension of Indian ink in sea water, a clear halo of mucilaginous material will be seen. A similar mucilage cover is also a well-known feature with certain phytoplankton organisms, in which cells of spiny appearance (e.g. freshwater desmids) assume a spherical form in Indian ink when the mucilage cover is also observed (Lund, 1959). The attachment of red algal spores is a process in which mucilage clearly plays some part (Suto, 1950; Nakazawa, 1958; Matsumoto, 1959; Boney, 1966; Linskens, 1966; Moorjani & Jones, 1972; Charters, Neushul & Coon, 1972; Chamberlain & Evans, 1973). Studies on the sinking rate and dispersal of red algal spores have been described (Suto, 1950; Boney, 1965, 1966; Coon, Neushul & Charters, 1972). There appears to be little information on the sizes of the spore mucilage sheaths, and on their likely significance in the planktonic phase of the spore's existence immediately after release. The present work gives the results of an investigation of the spore mucilage of fourteen species of red algae.

Lophodermium pinastri: certain fine-structural features of ascocarp morphology

As viewed by the electron microscope, the 'carbonaceous' appearance of the ascocarp clypeus in Lophodermium pinastri (Schrad) Chev. is due to a dark substance in the interhyphal spaces; this substance is believed to originate within the hyphae since the latter contain dark inclusions of the same electron density. The mucilaginous material in the ascocarp cavity is primarily in the nature of an acid mucopolysaccharide, together with minimal amounts of carbohydrates and proteins. Examination of the interthecial hyphae by means of scanning electron microscopy (SEM) shows them to be true paraphyses, not pseudoparaphyses as previously supposed.