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

Abstract

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.