MORPHOLOGICAL AND ECOLOGICAL STUDY OF PHYSODERMA DULICHII

A new species of aquatic Phycomycete, Physoderma dulichii Johns, parasitic on the aquatic sedge Dulichium arundinaceum (L.) Britt., is described from northern Michigan. This parasite infects and kills the upper epidermal cells of the host leaves. Macroscopically, infection by P. dulichii is indicated by striking brown bands with irregular margins, at intervals on the upper surfaces of the leaves. Like other species of Physoderma, this organism's development includes two distinct phases, an epibiotic monocentric phase producing asexual zoospores and an endobiotic polycentric phase bearing thick-walled resting spores that germinate after an extensive period of maturation at low temperature to form zoospores. The morphology and development of the two phases and of resting spore germination are reported in detail. Only the immature leaves of the host are susceptible to infection, which may be initiated by the introduction of mature resting spores, zoospores from germinated resting spores, or zoospores from epibiotic sporangia. Resting-spore zoospores may also produce the endobiotic stage directly. Initiation of infection in nature requires that the terminal cluster of immature leaves on the host plant be submerged, but infection of subsequently formed leaves of emergent culms can be accomplished through the agency of zoospores from epibiotic sporangia on older leaves. The relation of infected stands of hosts to their environment is discussed and the importance of standing water to infection noted. The geographical distribution of the parasite shows correlation with the drainage basins of the Great Lakes, the St. Lawrence River, and the northern Atlantic Coastal Plain     

Mycothallic/mycorrhizal symbiosis of chlorophyllous gametophytes and sporophytes of a fern, Pellaea viridis (Forsk.) Prantl (Pellaeaceae, Pteridales)

Gametophytes of Pellaea viridis that appeared spontaneously on the surface of substratum originating from an ultramafic area were found to form mycothallic symbiosis with arbuscular mycorrhizal fungi (AMF) under laboratory conditions. In gametophytes and sporophytes grown with Glomus tenue, abundant arbuscule formation was observed at both stages. In gametophytes, the fungus was found in the region where the rhizoids are initiated. If G. intraradices was added to the soil, the gametophytes were colonised mostly by G. tenue, and roots of sporophytes were colonised by G. intraradices. The presence of AM fungi in both gametophytes and sporophytes of P. viridis resulted in the development of larger leaf area and root length of the sporophyte. The analysis of gametophytes from the Botanical Garden in Krakow (Poland) showed that cordate gametophytes of Pteridales, namely Pellaea viridis (Pellaeaceae), Adiantum raddianum and A. formosum (Adiantaceae), were also mycothallic.     

Shooting of sporidium by "gun" cells in <Emphasis Type="Italic">Haptoglossa heterospora</Emphasis> and <Emphasis Type="Italic">H. zoospora</Emphasis> and secondary zoospore formation in <Emphasis Type="Italic">H. zoospora</Emphasis>

Haptoglossa spp. (Lagenidiales, Oomycetes) have been known to parasitize microscopic animals by means of a "gun" cell that shoots an infection cell, named the sporidium, into the body of the animal. A thallus grown from the sporidium changes into a zoosporangium at maturation to produce a number of zoospores that encyst after a swarming period, and the resulting cysts germinate to produce gun cells. In Haptoglossa zoospora, endoparasitic in nematodes, the cysts of primary zoospores that swam for about 5 min did not develop gun cells but produced secondary zoospores that swam for about 3 h. After encystment of the secondary zoospores, each secondary cyst germinated to produce a gun cell. In the present study, the secondary zoospores of the genus Haptoglossa could be recorded with a videocassette recorder for the first time. The videocassette recording also revealed the infection of a nematodes by H. zoospora and H. heterospora to be composed of two steps of injection of a sporidium by the gun cell, in which the gun cell came in contact with the cuticle of a nematode and produced a spherical adhesorium on the tip of the cell in 0.07–0.1 s in both species. The adhesorium was ∼2 μm in H. zoospora and ∼4 μm in H. heterospora. When the adhesorium infiated to full size, it shot the sporidium into the nematode's body in 0.5–0.65 s and in 0.2–0.5 (or rarely 1.0) s in H. zoospora and H. heterospora, respectively. After shooting, the empty gun cell with an empty cyst case was separated from the cuticle immediately in both species. Received: October 3, 2001 / Accepted: December 13, 2001     

PSEUDULVELLA AMERICANA BELONGS TO THE ORDER CHAETOPELTIDALES (CLASS CHLOROPHYCEAE), EVIDENCE FROM ULTRASTRUCTURE AND SSU RDNA SEQUENCE DATA1

The genus Pseudulvella Wille 1909 includes epiphytic, freshwater, or marine disk‐shaped green microalgae that form quadriflagellate zoospores. No ultrastructural or molecular studies have been conducted on the genus, and its evolutionary relationships remain unclear. The purpose of the present study is to describe the life history, ultrastructural features, and phylogenetic affiliations of Pseudulvella americana (Snow) Wille, the type species of the genus. Thalli of this microalga were prostrate and composed of radiating branched filaments that coalesced to form a disk. Vegetative cells had a pyrenoid encircled by starch plates and traversed by one or two convoluted cytoplasmic channels. They had well‐defined cell walls without plasmodesmata. Asexual reproduction was by means of tetraflagellate zoospores formed in numbers of two to eight from central cells of the thallus. The flagellar apparatus of zoospores was cruciate, with four basal bodies and four microtubular roots. The paired basal bodies lay directly opposite (DO) one another. The microtubular root system had a 5‐2‐5‐2 alternation pattern, where the “s” roots contained five microtubules in a four‐over‐one configuration. A tetralobate nonstriated distal fiber connected all four basal bodies. A wedge‐shaped proximal sheath subtended each of the basal bodies. The ultrastructural features of the zoospores were those of members of the order Chaetopeltidales. Phylogenetic analyses based on SSU rDNA placed P. americana sister to Chaetopeltis orbicularis in a well‐supported Chaetopeltidales clade. Such a combination of features confirmed that this alga is a member of the order Chaetopeltidales.     

The fate of chloroplast DNA during cell fusion, zygote maturation and zygote germination in Chlamydomonas reinhardi as revealed by DAPI staining

Chlamydomonas reinhardi, a haploid isogamous green alga, presents a classic case of uniparental inheritance of chloroplast genes. Since the molecular basis of this phenomenon is poorly understood, an examination of the cytology of the C. reinhardi plastid DNA was made in gametes, newly formed zygotes, maturing zygotes, and at zygote germination.The single plastid per cell of Chlamydomonas contains a small number of DNA aggregates (‘nucleoids’) which can be seen after staining with DNA-binding fluorochromes. In zygotes formed by pre-stained gametes, the fluorescing nucleoids disappear from the plastid of mating type minus (male) gamete plastids but not from the plastid of mating type plus (female) gamete plastids about 1 h after zygote formation. Subsequently, nucleoids aggregate slowly to a final average of two or three in the single plastid of the mature zygote.Quantitative microspectrofluorimetry indicates that gametes of both mating types have equal amounts of plastid DNA, and that zoospores arising from zygotes have 3.5 × as much as gametes. Assuming degradation of male plastid DNA, there must be a very major synthesis of plastid DNA between zygote formation and zoospore release when zygotes produce the typical 8–16 zoospores. That synthesis appears to occur at germination, where there is a massive increase in plastid DNA and nucleoid number beginning just prior to meiosis. The results support the theory that uniparental inheritance results from degradation of plastid DNA entering the zygote via the male gamete and suggest further studies, using mutants and altered conditions, which might explain how male plastid DNA sometimes survives.     

Attraction and attachment of zoospores of the parasitic chytridRozella allomycis in response to host-dependent factors

Summary This study examined the behavior of populations of zoospores of the obligately parasitic, endobiotic chytridRozella allomycis towards young, vegetative thalli of various saprophytic fungi, in order to identify host-dependent factors which control the development ofRozella. An inverted microscope was employed for continuous observation of parasite-host interaction in petri dishes of broth or agar medium. Two factors appear to control the initial stages of invasion byRozella of both susceptible and resistant species of the host genus,Allomyces: (i) a soluble exudate which attractsRozella zoospores, (ii) a receptor on the cell-wall surface which causesRozella zoospores to adhere, and to encyst and to germinate immediately thereafter. A related, nonsusceptible species,Blastocladiella emersonii, also attractsRozella zoospores, but supports very limited attachment.Rozella zoospores neither accumulate around, nor adhere to young thalli of non-blastocladialean fungi. This host-specific behavior pattern is compared with that of saprophytic and facultatively parasitic Phycomycetes, whose zoospores show nonspecific chemotactic responses and require no receptor for attachment, encystment and germination.     

SCHIZOMERIS—A GROWTH FORM OF STIGEOCLONIUM TENUE (CHLOROPHYTA:CHAETOPHORACEAE)1

Schizomeris leibleinii Kütz. was found as an ecophene of Stigeoclonium tenue (Ag.) Kütz. in Centennial Lake, Palmerston North, New Zealand. The Schizomeris form occurred in autumn when the water was polluted by a large number of ducks. Sampling of the plant population of the lake and culture work showed that S. tenue has a high degree of polymorphism. Other forms of it which developed both in the lake and in culture were indistinguishable from Protoderma Kütz. emend. Borzi, from Uronema Lagerheim, or from Pearsoniella Fritsch and Rich, respectively.     

NORTHERN AND SOUTHERN HEMISPHERE HYBRIDS OF MACROCYSTIS (PHAEOPHYCEAE)1

All combinations of individuals of Macrocystis pyrifera (L.) C. Agardh, M. integrifolia Bory, and M. angustifolia Bory hybridized. Gametophyte isolates obtained from 18 individuals were used, including M. pyrifera and M. integrifolia from the extremes of their Northern Hemisphere ranges along the Pacific Coast of North America and M. pyrifera and M. angustifolia from Tasmania, Australia. All combinations of gametophytes produced sporophytes of normal morphology, with the exception of crosses involving three gametophyte isolates. One female (M. integrifolia) and two male (M. pyrifera and M. angustifolia)gametophyte isolates were unable to produce normal sporophytes in combination with gametophytes of the opposite sex. Some cultures of female gametophytes produced abnormally shaped parthenogenetic sporophytes. Gametophytes and sporangia of M. pyrifera had n= 16 chromosomes. The M. integrifolia female gametophyte that was unable to produce normal sporophytes had n = ca. 32 chromosomes. These results show that these species of Macrocystis have not become reproductively isolated. Although these species may be considered conspecific according to the biological species concept, we recommend that they continue to be recognized as separate species based on morphological differences.     

Fungal zoospores are induced to encyst by treatments known to degrade cytoplasmic microtubules

Summary Zoospores of the obligately parasitic chytrid Rozella allomycis encyst and germinate after settling on a hypha of the host, the watermold Allomyces arbuscula. Zoospores deprived of a host also encyst after aging, but do not germinate. Hence, means were sought to induce encystment of young zoospores, in order to test whether they would subsequently germinate in the absence of a host.Zoospore suspensions were harvested and exposed to treatments known to degrade cytoplasmic microtubules and to depolymerize fibrillar structures in other organisms: ice temperature, hydrostatic pressure of 2000–10000 psi, cupric ions, and colchicine. These treatments induced rapid encystement—but no germination.The results suggest that the motility, the flagellated state, and the irregular, elongate shape of fungal zoospores depend on the intactness of their fibrillar skeletal structures. The results also support the hypothesis that contact of Rozella with the host surface has two sequential functions: (i) nonspecific (replaceable by other treatments) triggering of encystment, (ii) specific stimulation of germination.     

Causation of reversal simultaneity for diatom biomass and density of <Emphasis Type="Italic">Phormidium tenue</Emphasis> during the warm season in eutrophic Lake Barato,Japan

The diatom biomass of Lake Barato, as measured from July to September, decreased simultaneously with an increase in filament density of Phormidium tenue after 1997. There was a high negative correlation between the diatom biomass and the densities of P. tenue (r² = 0.928). Although total nitrogen (TN) and total phosphorus (TP) concentrations decreased from 1996, TN:TP ratio increased from 1997 because the TP concentration became markedly lower. The decrease in diatom biomass might have been due to the loss in phosphorus available for algae. Because the increase in density of P. tenue might have been due to the decrease in diatom biomass, experiments using a growth inhibitor for diatoms were performed to examine whether the density of cyanobacteria increases without diatom growth. Samples of the lake water collected in three seasons (August and October 1998, May 1999) were incubated with and without germanium (Ge) as a growth inhibitor of diatoms. The increase in density of P. tenue was inhibited concurrent with the increase in diatom biomass in the first and middle stages of incubation without the addition of Ge in August 1998 and May 1999. In contrast, a higher density of P. tenue was observed in the incubation with diatom growth inhibited by Ge over the same period. These results suggest that diatoms have an effect in restraining the growth of P. tenue.     

OBSERVATIONS ON THE LIFE HISTORY OF PAPENFUSSIELLA CALLITRICHA (PHAEOPHYCEAE,CHORDARIALES) IN CULTURE1

Papenfussiella callitricha (Rosenv.) Kylin from eastern Canada was studied in culture. Zoids from unilocular sporangia develop into microscopic, filamentous, dioecious gametophytes which produce isogametes in filament cells and few-chambered plurilocular gametangia. Unfused gametes germinate to reproduce the gametophytes. Fusion takes place between a settled (“female”) and a motile (“male”) gamete. The zygote gives rise to a filamentous plethysmothallus that reproduces asexually by zoids formed in thallus cells and in few-chambered plurilocular zoidangia. Erect macrothalli are produced on the plethysmothallus, beginning with the formation of upright filaments. Later on, these filaments become the terminal assimilators of the macrothalli. Further assimilatory filaments, rhizoids, and unilocular sporangia are produced in a branching region at the base of the terminal assimilator. Zoids from unilocular sporangia formed in culture germinate to reestablish the gametophyte phase. Chromosome counts yielded n = 19 ± 3 for the gametophytes, and 32 ± 6 for the sporophyte, both plethysmothallus and macrothallus.     

INTERGENERIC HYBRIDIZATION AMONG FIVE GENERA OF THE FAMILY LESSONIACEAE (PHAEOPHYCEAE) AND EVIDENCE FOR POLYPLOIDY IN A FERTILE PELAGOPHYCUS×MACROCYSTIS HYBRID

Hybridization was attempted by combining gametophytes between intergeneric pairs among the following taxa in the Lessoniaceae: Macrocystis pyrifera ( L.) C. Agardh , M. integrifolia Bory, M. angustifolia Bory , Pelagophycus porra ( Leman) Setch ., Nereocystis luetkeana ( Mert.) Post & Rupr ., Dictyoneurum californicum Rupr ., and Dictyoneuropsis reticulata ( Saud.) Smith. Hybrid sporophytes were produced in some combinations involving Macrocystis × Pelagophycus and Macrocystis × Dictyoneurum, and in all combinations of Dictyoneuropsis × Dictyoneurum. This is the first report of intergeneric hybrids involving Dictyoneurum. Gametophytes of P. porra had 16–24 chromosomes. Gametophytes from a fertile Macrocystis-Pelagophycus hybrid were crossed with Macrocystis and Pelagophycus gametophytes. Hybrid male gametophytes and Pelagophycus female gametophytes produced sporophyte progeny, but hybrid males with Macrocystis females did not. A single hybrid female gametophyte did not produce gametophytes in combination with hybrid males , Pelagophycus males or Macrocystis males. The hybrid gametophytes had approximately 30 chromosomes. It is hypothesized that the hybrid is an alloploid, containing a complete set of Macrocystis and Pelagophycus chromosomes, which may have allowed meiosis and sporogenesis to proceed normally in the hybrid sporophyte found in the sea. Thus, reproductive isolating mechanisms appear to operate at both pre- and postzygotic stages, and both can be overcome in intergeneric hybrids .     

Antheridiogen,dark spore germination,and outcrossing mechanisms in Bommeria (Adiantaceae)

Isozymic analyses of the patterns of genetic variability in sporophyte populations have demonstrated that most fern species have outcrossing breeding systems. However, because fertilization takes place during the ephemeral, diminutive gametophyte generation, direct observation of breeding systems in nature has not been possible. Recent discoveries of soil-bound spore banks suggested that genetic diversity could be stored beneath the surface and subsequently released by appropriate chemical cues. Previous studies demonstrated that Bommeria sporophytes are the product of outcrossing, that their gametophytes carry high levels of genetic load, and that they produce and respond to antheridiogen. Research reported here demonstrated that Bommeria spores can survive long-term storage but will not germinate in the dark. Antheridiogen, however, will release spores from this light requirement and stimulate germination. Higher concentrations of antheridiogen result in higher germination rates. Gametophytes grown in the dark on antheridiogen-enriched agar form antheridia and release actively swimming sperms. Thus, spores housed beneath the soil surface could remain dormant until stimulated to germinate by antheridiogen secreted by surface-dwelling, archegoniate gametophytes. Sperm released from these subterranean gametophytes could fertilize eggs on the surface. Because spores housed in the soil are likely to be genetically different than those at the surface, heterozygous sporophytes would be more likely to result. Discovering that Bommeria species contain all of the prerequisites for this proposed outcrossing mechanism provides an explanation for the maintenance of genetic diversity in some fern populations.     

MORPHOLOGY AND LIFE CYCLE OF A NEW CHYTRID WITH AERIAL SPORANGIA

An investigation of the life cycle of Caulochytrium gloeosporii Voos and Olive, a parasite of Gloeosporium, has confirmed the existence of an alternation of generations. Zoospores from sessile sporangia may develop vegetatively into similar sporangia or they may function as isogametes, fusing in pairs to produce cysts (zygotes) that give rise to slender-stalked aerial sporangia. Meiosis is believed to occur in the aerial sporangium, which at germination liberates eight asexual zoospores. The species is homothallic.     

THE DEVELOPMENT AND POSSIBLE RELATIONSHIPS OF A NEW ATKINSIELLA PARASITIC IN INSECT EGGS

Atkinsiella entomophaga is a holocarpic parasite in eggs of various midges and caddis flies. Primary zoospores escape through long discharge tubes and assume an abbreviated period of motility before encysting. Laterally biflagellate secondary zoospores subsequently emerge from the cysts. Coincident with discharge tube formation, the thallus undergoes strong vacuolization giving the protoplast a reticulate aspect with nuclei situated between the vacuoles and connected to one another by protoplasmic threads. Stages in zoosporogenesis resemble those of members of the Lagenidiales. It is proposed that Atkinsiella be included in the Eurychasmaceae along with Eurychasma and Eurychasmidium and that the family be transferred to the Lagenidiales. All members of this family have diplanetic zoospores.     

Shooting of sporidium by “gun” cells in Haptoglossa heterospora and H. zoospora and secondary zoospore formation in H. zoospora

Haptoglossa spp. (Lagenidiales, Oomycetes) have been known to parasitize microscopic animals by means of a “gun” cell that shoots an infection cell, named the sporidium, into the body of the animal. A thallus grown from the sporidium changes into a zoosporangium at maturation to produce a number of zoospores that encyst after a swarming period, and the resulting cysts germinate to produce gun cells. In Haptoglossa zoospora, endoparasitic in nematodes, the cysts of primary zoospores that swam for about 5min did not develop gun cells but produced secondary zoospores that swam for about 3h. After encystment of the secondary zoospores, each secondary cyst germinated to produce a gun cell. In the present study, the secondary zoospores of the genus Haptoglossa could be recorded with a videocassette recorder for the first time. The videocassette recording also revealed the infection of a nematodes by H. zoospora and H. heterospora to be composed of two steps of injection of a sporidium by the gun cell, in which the gun cell came in contact with the cuticle of a nematode and produced a spherical adhesorium on the tip of the cell in 0.07–0.1 s in both species. The adhesorium was ~2 μm in H. zoospora and ~4 μm in H. heterospora. When the adhesorium inflated to full size, it shot the sporidium into the nematode's body in 0.5–0.65 s and in 0.2–0.5 (or rarely 1.0) s in H. zoospora and H. heterospora, respectively. After shooting, the empty gun cell with an empty cyst case was separated from the cuticle immediately in both species.     

DICTYOSTELIUM AUREO-STIPES AND DICTYOSTELIUM TENUE: NEW SPECIES OF THE DICTYOSTELIACEAE

Three new cellular slime molds, Dictyostelium aureo-stipes sp. n., D. aureo-stipes var. helvetium var. n. and D. tenue sp. n., are described which possess characteristics heretofore unrecorded in the Dictyosteliaceae. The two species are unlike in dimensions and complexity of form, yet show a number of features in common, and may in fact be closely related. D. aureo-stipes var. helvetium is relatively large and robust, forming multiple-branched fruiting bodies without the regularity of form found in Polysphondylium, yet tending toward symmetry when well-developed. The golden-yellow stipe is a distinguishing feature of D. aureo-stipes and is even more pronounced in var. helvetium. D. tenue is smaller and simpler in form. The degree of branching is much reduced, and oftentimes a solitary sorus terminates a delicate stipe composed of a single tier of cells. Both species are quite sensitive to environmental conditions, particularly temperature, for optimum development occurs within relatively narrow ranges.     

ON THE LIFE HISTORY OF MONOSTROMA FUSCUM (POSTELS ET RUPRECHT) WITTROCK1

Results of the study of Monostroma fuscum from Son Juan Island, Washington, fully support the separation of the species M. fuscum from Monostroma sensu Wittrock into a taxon including M. obscurum. It would appear from this and previous studies that the M. obscunim-M. fuscum complex is clearly Ulvacean. The characteristics of the complex include (1) alternation of morphologically similar haploid and diploid generations; (2) production of biflagellate gametes and quadriflagellate zoospores; (3) a uniseriate form in early ontogeny; (4) thallus development progressing through a vesicular stage that, as a result of localized degenerative processes, opens at a size of less than I cm into a monostromatic blade; (5) cells elongated perpendicular to the plane of the thallus and with rotund-truncate ends: (6) a single elongate plastid, thickened at the opposite poles of the cell and thinner in the equatorial region of the cell; (7) a thallus composed of cells with relatively inelastic walls; and (8) discrete discharge pores. The chromosome number of Monostroma fuscum is n =9. The first division of the zoosporangium nucleus is meiosis I.     

THE OCCURRENCE AND PHYLOGENETIC SIGNIFICANCE OF A MULTILAYERED STRUCTURE IN COLEOCHAETE SPERMATOZOIDS

Spermatozoid-forming cells of Coleochaete scutata were found in packets of four arranged in concentric internal bands. Spermatozoids, which occur singly in antheridial cells, are spherical to ovoid, approximately 7 μm long by about 3.9 μm wide. As compared to relatively unspecialized zoospores, male gametes undergo a number of specialized cellular changes during development. The spherical nuclei and cytoplasm of mature spermatozoids are increased in density. Posterior plastids are reduced and contain large starch grains. Many small mitochondria are clustered near the cell anterior. The plasmalemma is covered with a layer of flattened, diamond-shaped scales, while body scales of zoospores are pyramidal. The two flagella of both zoospores and spermatozoids are covered with flattened, diamond-shaped scales and hairs. The spermatozoids contain an anterior multilayered structure (MLS) structurally similar to, though smaller than, the MLS observed in zoospores. An asymmetrical cytoskeleton consisting of a band of 30–45 microtubules extends from the MLS down one side of the spermatozoid close to the plasmalemma. An immature MLS was observed in an early stage of spermatozoid development. The finding of an MLS and asymmetrical cytoskeleton in specialized male gametes as well as relatively unspecialized zoospores of Coleochaete strengthens assumptions of homology between MLSs of green algal reproductive cells and those found in flagellated spermatozoids of archegoniate plants. The structure of the spermatozoid of Coleochaete supports the hypothesis that this alga may be relatively close to the phylogenetic line which led directly to archegoniates.     

OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. XI. A PHYSODERMA ON AGROPYRON REPENS

Sparrow , Frederick K. (U. Michigan, Ann Arbor), Joyce E. Griffin , and Robert M. Johns . Observations on chytridiaceous parasites of phanerogams. XI. A Physoderma on Agropyron repens. Amer. Jour. Bot. 48(9): 850–858. Illus. 1961.—A Physoderma has been found in Michigan on Agropyron repens, which produces dark-brown, non-erumpent streaks up to 20 mm (usually 4–6 mm) in length by 0.5 mm in width and very local discoloration of the leaf blades and sheaths. There is no systemic infection, and plants parasitized are normal in size and bear flowers. Resting spores upon germination produce zoospores which may develop either into the endobiotic, poly-centric, resting spore-bearing thallus or into monocentric, epibiotic, ephemeral sporangia. The latter bear either colorless or orange globuled zoospores. These zoospores may give rise to new epibiotic sporangia, or, apparently without fusing in pairs, to the endobiotic system. Comparison with other congeneric fungi reported on Agropyron repens reveals the Michigan fungus to be distinct from them. Whether it can be embraced within Physoderma graminis (Büsgen) de Wild. or other described taxa on grasses awaits the results of future cross-inoculation studies.