Sze-Wing Wong

Proboscispora aquatica gen. et sp. nov., from wood submerged in freshwater

A new freshwater ascomycete genus Proboscispora is introduced to accommodate P. aquatica collected on wood submerged in streams in Australia and the Philippines. Proboscispora is characterized by having immersed, ellipsoidal, papillate ascomata, septate tapering paraphyses, cylindrical unitunicate asci with a refractive apical ring, and 3-septate, hyaline ascospores provided with coiled or proboscis-like bipolar filamentous appendages. Proboscispora aquatica is illustrated at the electron microscope level and is compares with Annulatascus, Ceratosphaeria, Ceriospora, Ceratostomella and Rivulicola , with which is shares some common characters.

Cataractispora gen. nov. with three new freshwater lignicolous species

A new genus of freshwater ascomycetes, Cataractisopora , with three new species: C. aquatica, C. appendiculata and C. viscosa , are described. These fungi occur on decaying wood and possess similar characteristics including coriaceous globose ascomata, wide septate paraphyses, cylindrical asci with a relatively massive refractive apical ring and ascospores with polar chambers and filamentous appendages. Appendage material accumulates within the polar chambers and, on release from the ascus, the ascospore appendage unfurls to form long threads. The appendage material is fibrillar at the ultrastructural level, and is derived from episporial projections at the ascospore tip. Although these three fungi are similar to species of Annulatascus , they are assigned to a new genus – Cataractispora based on their unique appendage ontogeny. Annulatascus bipolaris is also assigned to Cataractispora on the basis of its ascospore appendage ontogeny.

Ultrastructural studies on the aquatic ascomycetes Annulatascus velatisporus and A. triseptatus sp. nov.

Annulatascus species are common freshwater ascomycetes in the tropics. In this paper, the type species, Annulatascus velatisporus, and a new species, A. triseptatus, are described and illustrated at light and electron microscope levels. Annulatascus triseptatus differs from A. velatisporus in having three-septate ascospores surrounded by a thin sheath. The asci of both species have bilamellate ascus walls and a bipartite apical ring. The upper part of the apical ring differentiates from the inner ascus wall layer and the lower part elongates downwards during maturation. The mesosporium is the first formed ascospore wall layer followed by the episporium, which is covered with verruculose ornamentations. The mucilaginous sheath of the ascospores is fibrillar or amorphous depending on the fixation methods employed, and appears to be derived from the episporial verruculose ornamentations.

Lignicolous freshwater Ascomycota from Thailand : Micropeltopsis quinquecladiopsis sp. nov.

A new freshwater ascomycete Micropeltopsis quinquecladiopsis sp. nov. was collected on submerged twigs in a stream in Thailand. The fungus is described at the light microscope, scanning and transmission electron microscope level. Distinctive features are the appendaged 1-septate hyaline ascospores. The appendage arises as an outgrowth of the episporium from a basal stalk, then divides into five arms (three long and two short). The episporium and appendages are surrounded by an indistinct (at light microscope level) mucilaginous layer. The fungus is assigned to the Dothideales (Trichothyriaceae). Ascospore appendage ontogeny is compared with those of marine Ascomycota (Halosphaeriales).

Ultrastructural studies on the Myelospermaceae fam. nov., with a new species of Myelosperma

Ultrastructural and morphological studies have been carried out on M. tumidum , the type species of Myelosperma. Asci are provided with a distinctive refractive subapical ring, which differs from that found in other unitunicate families. The ascospores are reniform in all species and surrounded by mucilaginous sheaths of various shapes. Numerous ascomata also develop in a circle around a common central pore. At the Ultrastructural level the ascus apex comprises an electron-transparent thickening incorporating a subapical electron-dense hemispherical ring-like structure and the ascus wall is continuous over the apex. This type of ring is compared with those found in representative species in other related families. Based on these observations, a new family, the Myelospermaceae, is introduced, to accommodate Myelosperma. The rationale behind this is discussed, and M. alata is described to accommodate a remarkable new species from the Seychelles. Arguments for the possible inclusion of Manokwaria, Palmicola and Pemphidium in the Myelospermaceae are given.

Ultrastructure of the dimorphic ascospores in Mamillisphaeria dimorphospora

The ultrastructure of the dimorphic ascospores of Mamillisphaeria dimorphospora are illustrated. The small brown ascospores differ from the larger hyaline ascospores in having a thick melanin layer in the ascospore wall. They are also 2–3 times smaller and do not germinate on PDA. The significance of these observations with respect to dispersal of aquatic fungi is discussed. The large hyaline ascospores may be morphologically adapted to dispersal in streams, while the smaller brown ascospores are thought to be adapted to aerial dispersal. The reasons for this are discussed. The method by which two spore types can be produced in separate asci in one ascoma is hypothesised.

Apiosordaria striatispora, an endophyte of Mesua ferrea and Prunus arborea from Thailand

Apiosordaria striatispora isolated as an endophyte ofMesua ferrea andPrunus arborea is described, and illustrated with interference contrast light micrographs and scanning electron micrographs.