Tadayoshi Ito

Two new Halophytophthora species,H.tartarea and H.masteri,from intertidal decomposing leaves in saltmarsh and mangrove regions

Two new pythiaceous fungi were obtained from decaying leaves submerged in saltmarsh environments of the east coast of the U.S.A., or fringing mangroves in the Bahama Islands, and are described here asHalophytophthora tartarea andH. masteri. The two species have superficially similar zoosporangia whose dehiscence tubes have ragged-looking apices. However, differences in fine structures and development of the dehiscence tube and plug, characteristics of the dehiscence plugs, and presence or absence of vesicles clearly distinguish the two species.Halophytophthora masteri is the only species ofHalophytophthora that has a zoospore release mechanism involving both an extruded plug and a vesicle. Cultural properties concerning growth and asexual reproduction at various salinities and temperatures are also different between the two, probably reflecting adaptation to their respective habitats. Though zoospore release inH. masteri occurs spontaneously from mature zoosporangia, it is remarkably enhanced inH. tartarea and alsoH. masteri by mildly dehydrating mature zoosporangia followed by rewetting with seawater, which suggests a possible relation between the asexual reproduction of these oomycetes and the tidal rhythm in their natural habitats.

Surculiseries rugispora gen. et sp. nov., a new endophytic mitosporic fungus from leaves of Bruguiera gymnorrhiza.

Surculiseries rugispora gen. et sp. nov. is described as an endophytic fungus from leaves ofBruguiera gymnorrhiza in mangrove forests in the Iriomote Is., Okinawa, Japan. This fungus develops peculiar conditiongenous cells that resemble octopus legs with obvious sucker-like scars, and produces lentiform conidia with lines on surface. Sequence analysis of 18S rDNA places this new fungus in the family Xylariaceae and shows its close affinity to the genusAscotricha (anamorph:Dicyma).

Aniptodera salsuginosa, a new mangrove-inhabiting ascomycete, with observations on the effect of salinity on ascospore appendage morphology

Aniptodera salsuginosa sp. nov. from intertidal decomposing mangrove wood is described, and its unique ascospore appendages and ascus apical apparatus are illustrated. The ascospore appendages were functional only when they were submerged in brackish water. The ascus tip is composed of a thickened apical ring (disc) with a pore, which is nonfunctional for ascospore release. Ascospores were discharged through a fissure in the ascus wall at the margin of the apical disc. Evolution and adaptation of the new fungus and related mangrove ascomycetes to aquatic environments from terrestrial habitats are briefly discussed.

Lanceispora amphibia gen. et sp.nov., a new amphisphaeriaceous ascomycete inhabiting senescent and fallen leaves of mangrove.

Lanceispora amphibia gen. et sp. nov. in the Amphisphaeriaceae is described from senescent and fallen leaves ofBruguiera gymnorrhiza in mangrove forests in the Southwest Islands, Japan. The fungus produces immersed ascomata in leaf tissue, cylindrical asci with an apical ring staining blue with iodine, and oblanceolate ascospores with a septum above the middle. Studies on the fungal succession on the mangrove leaves revealed thatL. amphibia infects senescent leaves on the tree and inhabits intertidal fallen leaves, showing the highest frequency of occurrence at the late stage of decomposition. In culture the optimal conditions for hyphal growth were 20 ppt salinity and 30°C, and those for sexual reproduction were 10 ppt salinity and 25°C. Growth at 0 ppt (fresh water) was depressed. The fungus has amphibious habits, growing on the tree and in intertidal water; and it is adapted to the high osmotic conditions in leaf tissues of the mangrove tree and to the subtropical, brackish water environment of mangrove forests.

Retrostium amphiroae gen et sp. nov. inhabiting a marine red alga, Amphiroa zonata.

Retrostium amphiroae gen. et sp. nov. (Spa- thulosporaceae), a fungus inhabiting Amphiroa zon- ata (marine Rhodophyta) in coastal habitats in Japan, is described. This fungus produces mononematous spermatiophores with penicillate phialides and trich- ogynes at the edge of ascomata on the surface of the host alga. The ostiolar canal of the ascoma has a tube- like projection extending into the ascomatal cavity, a feature that is shared only with some species of Chad- efaudia and Haloguignardia. Comparison of the new fungus with Spathulospora and Hispidicarpomyces spe- cies (Spathulosporales) in morphology, life history and host suggests that it has mixed characteristics of the two genera. The new fungus is inferred to be a phylogenetic link between the spathulosporalean fungi and other algae-inhabiting marine fungi in the genera Chadefaudia and Haloguignardia.

A new Halophytophthora species, H. porrigovesica, from subtropical and tropical mangroves

A new oomycete was found from intertidal fallen leaves of mangroves in Japan and Thailand and is described here asHalophytophthora porrigovesica. This species is characterized by having an epapillate, ovate zoosporangium with a lens-shaped dehiscence plug-like material at the apex, and by forming an expanding long cylindrical vesicle prior to zoospore release. A key to 14 species and 2 varieties ofHalophytophthora including the new species is proposed. The subtropical (Iriomote is., Japan) strains and tropical (Thailand) strains were different in physiological properties and especially in the asexual reproduction. The subtropical strains showed a lower optimal temperature and wider range of suitable temperature and salinity for zoosporangium formation, whereas the tropical strains showed a higher optimal temperature and narrower range of temperature and salinity. These differences are explained as adaptations of the strains to the environmental conditions of their respective habitats. From the subtropical mangroves, six strains of the new species have been isolated only from submerged leaves ofSonneratia alba, while several strains have been isolated from tropical mangroves from the leaves of three species of mangrove trees,S. alba, Bruguiera gymnorrhiza andAvicennia alba. This indicates a change of taxon selectivity (host specificity) with the geographical distribution.

Two species of Acremonium section Acremonium: A. borodinense sp. nov. and A. cavaraeanum rediscovered

Two unusual species of Acremonium sect. Acremonium, A. borodinense sp. nov. and A. cavaraeanum, are described and illustrated. They were isolated in Japan from rhizosphere soil of sugarcane and an outer wall of a wooden house respectively. A. borodinense is characterized by forming two kinds of conidia, ellipsoidal rough-walled and cylindrical smooth-walled. Of A. cavaraeanum a second isolate has become available; it forms long chains of fusiform conidia, has a luteous reverse and exudes a livid-red pigment into the medium.

Thielavia aurantiaca, a new species from Japanese soil

A new species ofThielavia (T. aurantiaca) isolated from field soil collected from Osaka is described and illustrated. The fungus is distinguished from other known species by having ascomata covered with yellowish orange mycelium and smaller size of ascomata and ascospores. A chlamydospore-like anamorph is formed.

Zoosporangium development, zoospore release and culture properties of Halophytophthora mycoparasitica

Halophytophthora mycoparasitica, a fungal parasite with unique zoosporangial ornamentation, was isolated from submerged fallen leaves of mangrove collected in the South-west Islands, Japan, since the original description from Malaysia. Isolates were examined for the development of zoosporangia and the process of the zoospore release. Scanning electron microscope observation revealed that the denticulate ornamentation of the surface of the zoosporangium is composed of many sets of assembling spines which are densely covered with mucilage. The mucilage is exuded from the spines and spreads over the zoosporangium as the zoosporangium develops. The mucilage works to gather spines into groups, which are angled towards the center of each assembly. Details were observed on the process from dehiscence plug development, through its ejection, to zoospore release. Mycoparasitic behavior was also observed in a mixed culture with a host fungus. Culture studies showed the species adapts well in its growth and asexual reproduction to brackish and sea water in a mangrove environment.

Taxonomy and ecology of Dactylella iridis: Its redescription as an entomogenous and nematode-capturing hyphomycete

Trinacrium iridis, Dactylella ramiformis, and our own isolates obtained from a dead midge were proved to be a single species by means of morphological, ecological and DNA homology studies. The simple-pore septal ultrastructure and Q-10 (2H) ubiquinone of this fungus revealed its ascomycetous affinity. Morphological and ecological characteristics of this species led it to be accomodated in the genusDactylella. The fungus is redescribed here, because the combined nameD. iridis has been defectively issued. We have corrected nomenclatural errors and described all characteristics of this species.Dactylella iridis produces three types of conidia; Y-shaped aquatic, cylindrical aerial or terrestrial, and ellitical secondary conidia. The production of the former two types of conidia is enhanced by wetting mycellia grown on a sterilized midge body on silkworm, chrysalis extract agar plates. All the strains examined have a predatory behavior on nematodes. Thus, the fungus has versatile talents for aquatic, terrestrial, saprophytic, entomogenous and nematophagous lives.