T.K. Goh

Role of fungi in freshwater ecosystems

There are more than 600 species of freshwater fungi with a greater number known from temperate, as compared to tropical, regions. Three main groups can be considered which include Ingoldian fungi, aquatic ascomycetes and non-Ingoldian hyphomycetes, chytrids and, oomycetes. The fungi occurring in lentic habitats mostly differ from those occurring in lotic habitats. Although there is no comprehensive work dealing with the biogeography of all groups of freshwater fungi, their distribution probably follows that of Ingoldian fungi, which are either cosmopolitan, restricted to pantemperate or pantropical regions, or in a few cases, have a restricted distribution. Freshwater fungi are thought to have evolved from terrestrial ancestors. Many species are clearly adapted to life in freshwater as their propagules have specialised aquatic dispersal abilities. Freshwater fungi are involved in the decay of wood and leafy material and also cause diseases of plants and animals. These areas are briefly reviewed. Gaps in our knowledge of freshwater fungi are discussed and areas in need of research are suggested.

Biodiversity of freshwater fungi

There are more than 600 species of freshwater fungi with more known from temperate, as compared to tropical regions. These includeca 340 ascomycetes, 300 deuteromycetes, and a number of lower fungi which are not discussed here.Aniptodera, Annulatascus, Massarina, Ophioceras andPseudohalonectria are common freshwater ascomycetes, which appear to be well adapted for this lifestyle either in their ascospore types or their competitive-degradative characters. The most common genera of wood-inhabiting deuteromycetes includeCancellidium, Dactylaria, Dictyosporium andHelicomyces. They are categorized into four groups depending on their form and life style: the ingoldian hyphomycetes; the aero-aquatic hyphomycetes; the terrestrial-aquatic hyphomycetes; and the submerged-aquatic hyphomycetes. The adaptations of aquatic fungi for their dispersal and subsequent attachment to new substrates are discussed.

Fungi on submerged wood in Lake Barrine, north Queensland, Australia

Results of an investigation into the fungi associated with submerged wood in Lake Barrine, north Queensland, Australia are reported. Thirty-nine fungi were identified, 15 ascomycetes, 23 deuteromycetes and one basidiomycetes. The frequency of occurrence and the effect of the incubation period on the recovery of fungi has also been investigated and is presented. The new species Massarina lunispora and Dactylaria lakebarrinensis, and some other notable species, are described and illustrated.

Fungi on submerged wood in the Palmiet River, Durban, South Africa

Results of an investigation into the fungi associated with submerged wood in the Palmiet River, Durban, South Africa are reported. Fifty eight fungi were identified including 28 Ascomycetes and 30 Hyphomycetes. Three are species new to science, including Annulatascus palmietensis K.D. Hyde, Goh & T.D. Steinke, Endophragmiella bitriseptata Goh, K.D. Hyde & T.D. Steinke, and Phialogeniculata africana Goh, K.D. Hyde & T.D, Steinke, and are described in this paper. The percentage occurrence of the fungi on wood is given and this is compared with other studies.

Fungi on submerged wood from the River Coln, England

Nine ascomycetes, 1 basidiomycete and 15 mitosporic fungi are reported from submerged wood, collected from a single English river site. Ascotaiwania pallida, Neta angliae and Trichocladium englandense spp. nov. and Frigidispora colnensis gen. & sp. nov. are described and illustrated. Most of the species present on the submerged wood appear to have been identified, for the single date and location sampled, because the asymptote of the accumulative curve was reached between 80–100 substrata. The results of this study are compared with those from collections, using similar collection techniques in tropical regions. Results suggest that temperate streams appear to have a lower fungal diversity than in the tropics. Only Acrogenospora sphaerocephala was common to tropical (Seychelles) and temperate (U.K., River Coln) sites.

FUNGI ON SUBMERGED WOOD IN THE RIVIERE ST MARIE-LOUIS, THE SEYCHELLES

Results of an investigation into the fungi associated with submerged wood in the Riviere St Marie-Louis, Seychelles, are reported. Thirty four fungi were identified including 12 ascomycetes, 20 hyphomycetes, one coelomycete and acanthophysis-like structures. The frequency of occurrence of these fungi has also been investigated. The most common species was Jahnula seychellensis K.D. Hyde and S.W. Wong, occurring on 30% of samples, while Verticillium sp. (26%), Annulatascus velatisporus K.D. Hyde (21%), Sporoschisma uniseptatum Bhat and W.B. Kendr. (15%) and Xylomyces chlamydosporis Goos, R.D. Brooks and Lamore (15%) were also common. These common species are compared with common species found in other studies. Astrosphaeriella seychellensis K.D. Hyde and Goh, sp. nov., Cordana abramovii De Hoog var. seychellensis K.D. Hyde and Goh, var nov., Ityorhoptrum verruculosum (M.B. Ellis) P.M. Kirk, and Veronaea coprophila (Subram. & Lodha) M. B. Ellis are described, illustrated and discussed.

New records and species of Sporoschisma and Sporoschismopsis from submerged wood in the tropics

During investigations of microfungi occurring on submerged plant material in tropical streams, seven species of Sporoschisma and one species of Sporoschismopsis were recorded. Three are newly described: Sporoschisma parcicuneatum, S. phaeocentri and Sporoschismopsis australiensis . Each of these species is described and illustrated in detail and a synopsis of remaining species of Sporoschismopsis is provided. Generic concepts and connections to teleomorphs are discussed and a key is provided to accepted species in both genera.

A revision of Dactylaria, with description of D. tunicata sp. nov. from submerged wood in Australia

Dactylaria tunicata sp. nov. from submerged wood in a freshwater stream from Australia is described and illustrated. It differs from all previously described species of Dactylaria in having uniseptate conidia with a hyaline sheath. The 41 species of Dactylaria accepted by de Hoog are listed together with a further 41 validly published species of Dactylaria post de Hoog. A taxonomic key to 37 of the 41 post de Hoog species is provided, based on the literature, together with a composite illustration of their conidial morphology. The other four species are discussed, but they are not considered to be Dactylaria species (sensu de Hoog).

Spadicoides cordanoides sp. nov., a new dematiaceous hyphomycete from submerged wood in Australia, with a taxonomic review of the genus

Spadicoides cordanoides sp. nov. occurring on submerged wood in north Queensland, Australia is described and illustrated. It differs from all previ- ously described Spadicoides species in having predom- inately obpyriform, versicolored, two celled conidia, in which the apical cell is verruculose. The current generic concept of the genus is briefly discussed and the 21 accepted species are illustrated. A key to Spad- icoides species is provided.

Four new species of Xylomyces from submerged wood

Xylomyces is re-examined, the type specimen X. Mamydosporis redescribed and illustrated, and new distribution records are provided. Four new species, X. elegans sp. nov., X. elegans sp. nov., giganteus sp. nov., X. punctatus sp. nov. and X. pusillus sp. nov. are described from wood submerged in freshwater collected in various countries. The chlamydospores of these species are drawn at the same scale as a composite diagram for comparison and each is illustrated with light micrographs. Xylomyces foliicola is regarded as atypical in the genus. A key to the accepted species in Xylomyces is provided.