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The new genus Rodaucea is created for a new species of Laboulbeniales parasitic on carrion beetles from Ecuador. The new genus is characterized by the presence of two unequal secondary receptacles flanking cell II on opposite sides. The perithecia have the wall cells arranged in four tiers distinctly unequal in height and the antheridia are phialid-like struc- tures borne terminally on branches of primary and secondary appendages.

A new species of Pythium isolated from soybean in Ohio is described. Pythium delawarii sp. nov. is characterized by globose internally proliferating sporangia, aplerotic oospores and diclinous antheridia that make broad lengthwise contact. Sporangia produce conspicuous papilla and germinate indirectly by producing zoospores via a vesicle and proliferate internally or the sporangia germinate directly with either one or more germ tubes. Pythium delawarii is pathogenic on soybean causing damping-off of seedlings. This oomycete can grow at 10-34 C with an optimum of 28 C. The sequence of the ITS1, 5.8S and ITS2 region of the rDNA did not match the sequence of any known Pythium species but was similar to P. citrinum, P. litorale and P. sterilum. P. delawarii can be distinguished from these three species based on the presence of aplerotic oospores and diclinous antheridia and the absence of hypogynous antheridia. Therefore biological, morphological and molecular data support the recognition of a new species.

Asexual and sexual reproductive structures of Peronospora viciae, which causes downy mildew of pea (Pisum sativum), were studied using low temperature scanning electron microscopy. Sporangiophores ...

Two distinct subgroups (L2 and A(-2)) were recovered from irrigation reservoirs and a stream in Virginia, USA. After molecular, morphological and physiological examinations, the L2 subgroup was named Phytophthora aquimorbida and the A(-2) designated as Phytophthora taxon 'aquatilis'. Both taxa are homothallic. P. aquimorbida is characterized by its noncaducous and nonpapillate sporangia, catenulate and radiating hyphal swellings and thick-walled plerotic oospores formed in globose oogonia mostly in the absence of an antheridium. P. taxon 'aquatilis' produces plerotic oospores in globose oogonia mostly with a paragynous antheridium. It has semi-papillate, caducous sporangia with variable pedicels, but it does not have hyphal swelling. Analyses of ITS, CO1, beta-tubulin and NADH1 sequences revealed that P. aquimorbida is closely related to P. hydropathica, P. irrigata and P. parsiana, and P. taxon 'aquatilis' is related to P. multivesiculata. The optimum temperature for culture growth is 30 and 20 C for E aquimorbida and P. taxon 'aquatilis' respectively. Both taxa were pathogenic to rhododendron plants and caused root discoloration, pale leaves, wilting, tip necrosis and dieback. Their plant biosecurity risk also is discussed. National Institute of Food and Agriculture (U.S.) - 2005-51101-02337 National Institute of Food and Agriculture (U.S.) - 2010-51181-21140

Self-sterile isolates of Pythium (type S or Pythium group HS) that possessed cultural growth characteristics and morphologies similar to P. ultimum var. ultimum produced antheridia and mated success? fully when paired with self-fertile (type O or homo? thallic) isolates of this species and P. ultimum var. spo- rangiiferum. The self-sterile isolates produced antheridia that fused with oogonia produced by self- fertile isolates of P. irregulare but the oogonia aborted. The self-sterile isolates were identified as male forms of P. ultimum, since they exclusively formed antheridia when paired with self-ferile isolates of this species. Progenies from crosses between male and self-fertile isolates displayed traits of recombination in culture, indicating normal sexual reproduction occurred dur?

Two new species of Pythium, pathogens of corn and soybean in Ohio, are described. Pythium schmitthenneri sp. nov. and Pythium selbyi sp. nov. both have morphological and sequence characteristics that place them in clade E1 of the genus Pythium. Morphology and sequence analysis of the ITS1-5.8S-ITS2 regions of these species were different from previously described species. The ITS region of Pythium schmitthenneri was 99.9% similar to P. acrogynum and 99.8% similar to P. hypogynum. All three species are characterized by globose to limoniform sporangia and plerotic oospores. Pythium schmitthenneri has mostly diclinous antheridia, compared to the strictly hypogynous antheridia of P. acrogynum and P. hypogynum. The temperature for growth of P. schmitthenneri is below 4 C to 32 C, and optimum growth is 18-25 C compared to 31-34 C for P. hypogynum. The ITS region of P. selbyi was 97.1% similar to P. longandrum and 97.5% similar to P. longisporangium. All three species are characterized by globose sporangia, mostly plerotic oospores, with one to two oospores per oogonium, and hypogynous or monoclinous antheridia. The temperature for growth of P. selbyi is below 4 to 32 C, with an optimum 18-25 C. These new species were widely dispersed throughout the soybean- and corn-producing regions in Ohio, making their characterization critical for managing the Pythium complex that causes seedling and root-rot disease in Ohio soybean and corn fields.

A root rot disease of cultivated tobacco called yellow stunt has been observed in the burley tobacco production areas of Brazil since the early 1990s. Root infecting fungi and straminipiles were isolated from the roots of diseased tobacco plants, including a semi-papillate, homothallic, slow growing Phytophthora species. Pathogenicity trials confirmed that Phytophthora sp. caused root rot and stunting of burley and flue-cured tobaccos. Morphological characteristics of the asexual and sexual stages of this organism did not match any reported Phytophthora species and were very different from the widely known tobacco black shank pathogen P. nicotianae. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA, β-tubulin and translation elongation factor 1-α regions indicated that this organism represents a previously unreported Phytophthora species that is significantly supported in clade 2 and most closely related to P. capsici. However P. glovera differs from P. capsici in a number of morphological characters, most significantly P. glovera is homothallic and produces both paragynous and amphigynous antheridia while P. capsici is heterothallic and produces only amphigynous antheridia. In this paper we confirmed pathogenicity of this species on tobacco and describe the morphological and molecular characteristics of Phytophthora glovera sp. nov.

A homothallic, papillate Phytophthora species causing foliar and fruit blight of noni (Morinda citrifolia var. citrifolia) in Hawaii was identified. The asexual phase of this species is characterized by the production of umbellate sporangiophores and papillate sporangia that are ellipsoid and obpyriform with conspicuously tapered bases and possess caducous, medium to long pedicels. The sexual phase is characterized by the production of oogonia with tapered bases, small amphigynous antheridia and thick-walled, plerotic oospores. The morphology of the taxon does not match any of the valid 95 Phytophthora species described to date. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA region (ITS) and the translation elongation factor 1 alpha (EF-1 alpha) of this taxon and those from other Phytophthora species from GenBank and the Phytophthora database indicates that the new taxon is most closely related to species in ITS clade 10, including P. kernoviae, P. boehmeriae and the recently described P. gallica. The most closely related species is P. kernoviae, an invasive plant pathogen causing bleeding stem lesions on forest trees (beech, Fagus sylvatica) and foliar necrosis of ornamentals (rhododendron, pieris and magnolia) in the UK, and isolated in New Zealand from necrotic cherimoya shoots and fruits and soil. Although the morphological characters of the sexual phase of P. morindae and P. kernoviae are similar, the umbellate sporangiophores produced by the new taxon marks the main morphological distinction. In this paper we describe the morphological characteristics, the phylogenetic relationships and pathogenicity characteristics that support the description of this taxon as a new species with the proposed name Phytophthora morindae sp. nov.

Isolates from avocado tree cankers have been recognized as a distinct subgroup within the P. citricola complex since 1974, both morphologically and molecularly (isozyme and amplified fragment length polymorphism [AFLP] analyses). This subgroup is formally separated from P. citricola after comparative DNA fingerprinting and sequence analyses of the ITS region, as well as by morphological examinations. This new taxon is homothallic, produces plerotic oospores with paragynous antheridia and noncaducous semipapillate sporangia. Morphologically it differs from other species of Waterhouse group III by producing many large bizarre-shaped sporangia and smaller oogonia with asymmetric capitate antheridia. It belongs to clade 2 and is phylogenetically closer to P. siskiyouensis, P. capsici and P. tropicalis than to P. citricola. P. mengei can be easily differentiated from its relatives in the same clade and other species of this morpho-group by DNA fingerprints and sequence analysis. This new taxon is named Phytophthora mengei sp. nov.

An unknown Phytophthora species was recovered in southwestern Oregon from rhododendron and tanoak leaf baits used for monitoring streams and soils for the presence of Phytophthora ramorum, from a blighted shoot of myrtlewood and from tanoak bark cankers. Isolates of this species yielded ITS-DNA sequences that differed substantially from other Phytophthora sequences in GenBank. Morphological features also differed from available descriptions of known Phytophthora species. Based on the combination of unique morphology and unique ITS sequences a new species is proposed. The new species, Phytophthora siskiyouensis, is homothallic with globose to subglobose oogonia, which may be terminal, sessile or laterally intercalary. Antheridia are capitate and mostly paragynous but sometimes amphigynous. Oospores are mostly aplerotic. Sporangia are variable but commonly ovoid to reniform, with apical, subapical or lateral semipapillae (occasionally more than one). Sporangia are terminal, subterminal or occasionally intercalary on unbranched sporangiophores, with basal, subbasal or lateral attachment. Sporangia are weakly deciduous, with variable length pedicels. This combination of characters clearly separates Phytophthora siskiyouensis from other known Phytophthora species.

One isolate of water mold from field soil in Shikoku Island, Japan, was Plectospira myriandra, rediscovered 59 years after its original description by Drechsler in 1927. During a survey of pythiaceous fungi in Japanese soils, an interesting fungus was isolated from a field in which bamboo had been grown in Nangoku City of Shikoku District (Island), Japan. This fungus was very similar to Aphanomcyes, but unlike Aphanomyces, it featured lobulate sporangia with uniseriate production of zoospores inside long evacuation tubes. Also, there were numerous antheridial elements per oogonium, and oospores and parthenospores borne in oogonia with and without antheridia, respectively. The morphology and taxonomy of the fungus identified as Plectospira myriandra Drechsler is described in this report. A preliminary report has been published (Watanabe, 1986).

The majority of the ascogonia which produced ascogenous hyphae did so after the trichogyne failed to complete plasmogamy in cultures of two isolates of Pyronema domesticum, a discomycete. Most of the ascogonia reproducing in this manner bore a trichogyne which failed to unite with a fertilizing element. Some of the trichogyne tips fused and established cytoplasmic continuity with an antheridium, sterile hypha, or the ascogonium which produced it, but cytoplasmic continuity was not established between the trichogyne base and ascogonium. Ascogenous hyphae were subsequently produced by these unfertilized ascogonia. Infrequently, plasmogamy involving an antheridium, sterile hypha, or ascogonium was completed. Further development of the apothecium followed the pattern established for an isolate of P. domesticum in which plasmogamy regularly occurred.

that, however, are larger in size, have a stouter perithecial stalk, flatter receptacle cells, and appendages and antheridia that are more numerous and differently shaped. Since Laboulbeniales occurring on many species of Orotrechus are still unknown or belong to the genus Laboulbenia, it does not seem possible, at present, to draw any conclusion about host phylogeny from the parasitic fungi, as has been recently done for Duvalius in Italy (2). It seems likely that because of the limited distribution of the genus Orotrechus, endemic in the eastern part of the Prealps, the various species have repeatedly come into contact with each other during their evolution. In any case, the presence of three so well-differentiated species of Rhachomyces suggests that the evolutionary history of the genus Orotrechus is rather ancient and complex. We wish to express our gratitude to I. Bucciarelli, G. and M. Etonti, R. Sciaky and A. Vigna Taglianti who, together with other entomologists too numerous to mention, supplied us with parasitized insects. We also wish to thank L. Cajani for the Latin translation of the diagnosis, G. Biagiotti and L. Zenobi for their help with the photographic plate, and I. Tavares for her critical reading of the manuscript.

Phytophthora humicola, a new species which forms large hyphal swellings with radiating hyphae, was isolated from soil of a citrus orchard in Taiwan. The fungus produces nonpapillate, nondeciduous sporangia and relatively large oogonia with predominantly paragynous antheridia, both with long stalks. Phytophthora humicola and P. insolita isolated from soil of a nearby citrus orchard were pathogenic to fruits of apple and cucumber but not sweet orange and eggplant.

Soil, mummified cocoa pods on trees, and pods from husk piles were examined for species of Phytophthora in several experimental cocoa field plots in Brazil. Phytophthora capsici and P. citrophthora were recovered from soil and from husk piles. Compatibility types Al and A2 of P. capsici were isolated from a single pod. Plerotic oospores of Phytophthora with amphigynous antheridia still attached to the oogonial stalk were found in pods from husk piles. Fifteen percent ofthe oospores removed from pods germinated. Twenty single-oospore isolates were compared with respect to colony and sporangia morphology, sporangium production, stalk lengths, and compatibility type. Most cultures from ger? minated oospores resembled P. capsici but some had unique characteristics that included noncaducous sporangia and large (> 50 /nm in length) sporangia. The majority of single-zoospore isolates from singleoospore cultures were similar to their respective parent cultures. However, some differed with respect to size of sporangia, caducity of sporangia, and compatibility type.

Cleistothecia of Monascus purpureus were initiated by formation of antheridia and ascogonia. A trichogyne protruded from the ascogonium and fused with the antheridium. Dichotomously branching ascogenous hyphae arose from the ascogonium and were covered by anastomosed flattened sterile hyphae from the stalk of the ascogonium. Crozier formation was followed by typical ascus development. Cellular structures within the centrum of the cleistothecium were wall-less with occasional exceptions. Typical ascospore-delimiting double membranes were formed interior to the ascus plasma membrane and developed toward the center of the ascus to delimit the ascospores. Sterile structures within the centrum became vacuolate, probably nourishing the asci and ascospores. Mature cleistothecia contained numerous smooth-walled ascospores protected only by the outer cell wall of the peridium.

(1987). A New Species of Pythium with Ornamented Oogonia from Algeria. Mycologia: Vol. 79, No. 5, pp. 797-802.

Light and electron microscopy of sexual reproduction in the endoparasite Olpidiopsis varians is discussed and compared with existing accounts of other oomycetous fungi. Thalli that develop sexually are smaller than thalli that develop apogamously. Oogonial thalli are attended by adjacent unicellular antheridial thalli and surrounded by a reticulate network of electron-opaque wall ornamentation. En? zymatic digestion revealed that the wall ornamentation is partially proteinaceous. Nuclear divisions, interpreted as meiotic, occur in the antheridium and oogonium prior to sexual fusion. Meiotic nuclei possess axial filaments during prophase I and a subsequent metaphase plate. The products of meiosis are four closely associated nuclei surrounding a dictyosome-ER complex. Some ofthe nuclei in sexually reproducing thalli degenerate during meiosis. Peripheral vacuoles within the antheridium expand and compress the cytoplasm while a pore develops between the antheridium and oogonium. The multi? nucleate antheridial cytoplasm enters the oogonium through the pore and retains its integrity for an undetermined period of time. A plug of wall material fills the antheridial/oogonial pore after sexual fusion. It is proposed that O. varians possesses a diploid life cycle with gametic meiosis.

Gonimochaete lignicola is described as a new species of nematode-destroying endopar? asite recovered from rotting wood. Segments of the infection thallus function as sporangia and produce solitary aerial evacuation tubes. The protoplasm in the sporangium migrates to the swollen tip of the evacuation tube where it differentiates into spores. The tip of the evacuation tube is cut off by a septum from the vacuolated remainder either before or after spore formation. Some thalloid segments function as antheridia or oogonia. The protoplasm migrates from the antheridium into the oogonium and a solitary, thick-walled, pitted oospore is produced. This is the first time the sexual state has been described for a species of Goni? mochaete and supports placement of this genus in the Lagenidiales. The genus Gonimochaete was erected by Drechsler (1946) based on a single species, G. horridula Drechsler, which parasitized nematodes in decomposed leaves of red maple, gathered near a pond in Delaware. Later, Barron (1973) described G. pyriforme as a parasite of the nematode Diploscapter in greenhouse soil. A third species, G. latitubus, was discovered by Newell et al. (1977) attacking rhabditid nematodes inhabiting the marine littoral zone in southeastern Florida. The sexual state was not reported for any of the described species. Gonimochaete horridula is remarkable in producing non-motile spores which gather in clusters at the mouths of aerial evacuation tubes. Each aplanospore produces an adhesive knob which may attach to the host and infect it by direct penetration through the cuticle. As it develops, the infection thallus breaks up into segments each of which eventually functions as a sporangium and produces a solitary evacuation tube which is elongate and oriented more or less vertically. The body of the sporangium becomes vacuolate and the dense protoplasmic contents are pushed up the evacuation tube. Spores are formed by horizontal cleavage of the protoplasm inside the tube and the mature spores are pushed to the exterior through an exit at the tip to form an aerial cluster of aplanospores. The evacuation tube now functions as a support stalk for the ejected spore mass. Turgidity of the evacuation tube is maintained by the formation of a cross wall at its tip. Thus the sporangium and associated support stalk probably remain alive for some time after spore release. A previously undescribed species of Gonimochaete was recovered during a study of parasites of rotifers and nematodes in rotting wood. In the size and shape of the spores, and in their manner of production, this species differs significantly from previously described species. Moreover, it produces oogonia, antheridia, and oospores similar to those found in some species of Mycocytium (Lagenidiales). Methods used to recover this fungus and study its life cycle have been described previously (Barron, 1977b).

Koralionastes Kohlm. & Volkm.-Kohlm., gen. nov. with the new species K. angustus, K. ellipticus and K. ovalis is described from coral slabs. These ascomycetes occur subtidally in shallow water of back reefs near small islands off the coast of Belize, Central America. Ascomata are attached to corallinecovered corals and are often enclosed by crustose sponges. Ascospores of all three species are thickwalled and germinate into hyphae bearing phialidic antheridia with enteroblastic spermatia. Because Koralionastes cannot be assigned to any known family, Koralionastetaceaefam. nov. (class Ascomycetes) is proposed.

SUMMARY Single-spore strains from six isolates of Dictyuchus monosporus exhibited the following types of behavior when mated to their respective parental strains and to tester strains of opposite mating reaction to that of the parental strains: (1) heterothallism, in which one of the strains reacted as male and produced antheridia which became applied to oogonia produced by the female-reacting strain; (2) heterothallism, preceded by homothallism in one of the strains in the region of contact between the paired strains, the homothallic strain reacting as male and the opposing strain as female; (3) homo-heterothallism, in which both strains were homothallic in areas adjacent to one another and both were involved in reciprocal cross reactions. With only one exception, there was no sexual reaction between the male isolates and the single-spore strains derived from them. The reactions of the single-spore strains derived from female isolates and mated to their respective parental strains were varied and differed according to the origin of the strains. Variations in sexual behavior also occurred among single-spore strains from some sporangia.

The genus Brevilegnia was established by Coker (1) on the basis of the following characters: (1) the presence of a depauperate dense mycelium; (2) the development of zo6sporangia which behaved "about as in Thraustotheca " (1, p. 212), i.e., discharged the spores by an irregular rupture of the sporangium wall, which disappeared after maturity; (3) the variability in sporangiospore size and the frequent failure of these spores to emit secondary swarmers; and (4) the formation of small, monosporic o6gonia. The type species was B. unisperma Coker, the distinguishing characters of which were the presence of many large, long-cylindrical sporangia; the complete disappearance of the sporangial wall simultaneous with the escape of the spores; the development of small, spherical, irregular, one-spored o6gonia; the formation of androgynous, profusely branched and irregular antheridia; and the occurrence of zo6spores. Other species and varieties were later described by Coker and others, separated from the type on the basis of such properties as the size and shape of the sporangia, the presence or absence of antheridia, the motility or lack of motility of the zo6spores, and the formation or absence of gemmae. When an isolate of Brevilegnia was obtained by the writer, attempts were made to determine to what species the fungus belonged. However, this was found impossible because of the wide variations in the morphology of the mycelium, asexual structures

SUMMARYAntheridal production was induced by the addition of 1,000 units/ml of hormone A to hyphae of Achlya ambisexualis. Electron microscopy of nuclear divisions within hyphae demonstrated the pre...

Investigations on the nature of the thallus in the Peronosporales have been confined to Phytophthora and Peronospora, in both of which complicated conditions exist within a single species. Studies on the sexual relations of species of Pythium with single zo6spore cultures have not been reported. Long cultural experience with the genus Pythium, however, has given no indication that heterothallism exists in the group. In spite, therefore, of investigating the obvious homothallism of Pythium, preliminary studies on single zo6spore cultures were undertaken. The majority of species of this genus are monoclinous, that is, the antheridia arise in more or less close proximity to the o6gonium; in the diclinous species the antheridia arise from hyphae showing no traceable connection with the hypha bearing the oogonium or only extremely rarely. If heterothallic forms exist they would more likely be diclinous. The work of Ashby (1, 2, 3), Narasimhan (9), Leonianr (7) and others shows that in Phytophthora though some species are definitely homothallic others, such as the P. palmlivora Butler group, may possess definitely homothallic strains, homothallic strains with heterothallic tendencies, heterothallic strains, and neutral or apparently sterile strains. More recently, Helena de Bruyn (4) has reported similar complicated conditions in the thallism of Peronospora parasitica (Pers.) Tul. De Bruyn inclines to the view, held by Leonian and others, that the heterothallic strains are not strictly unisexual, but possess the potentialities of both sexes, one sex being ordinarily dominant. It is not intended here to discuss the views or evidence on the r6le chemical substances may play in heterothallism in Phytophthora (cf. 6, 8). The following table gives information on the species studied in the present investigation.

Achlya DeBaryana Humphrey is the Achlya polyandra of DeBary, not of Hildebrand, as Humphrey has shown;1 and as Hildebrand's name is the older and applies to another plant, Humphrey's name should be used. Recent writers on the morphology of this species have ignored this and still call the plant Achlya polyandra DeBary. There are now recognized three very closely related species, forming what was called by Humphrey the prolifera group, which from the work of recent writers are becoming more and more difficult to separate. They are Achlya prolifera (Nees) DeBary, A. DeBaryana Humphrey, and A. anmericana Humphrey. Humphrey was himself aware of the very close resemblances of these species and remarked upon it; but on account of DeBary's assurance of the autonomy of the first two, felt called on to continue the distinction. According to DeBary,2 A. DeBaryana (his A. polyandra) has antheridial branches that arise from the same main hyphae that bear the oogonia, and then branch and extend out to the o6gonia on the branches from which they arose (which is most common) or to o6gonia on other threads. In A. prolifera, on the other hand, he says that the antheridial branches are diclinous, always arising from other hyphae than the ones that bear the o6gonia and that all o6gonia are furnished with antheridia. He also says that while A. prolifera has o6gonia with abundant pits, the oogonia of A. DeBaryana is without them. Achlya americana has antheridial branches that arise from the same hyphae as the o6gonia, and it also has

Nees von Esenbeck ('23) first separated the then known forms of water molds into two genera, Achlya and Saprolegnia, but, until the time of de Bary's first paper ('52) in I852, this distinction was not recognized by subsequent workers; de Bary revived the classification of the older author. Meanwhile all forms of water molds had been called Saprolengia ferax or Achlya prolifera, without any clear distinction being made between these genera. In I850, Thuret ('50) described the swarm spores of a form that he called S. ferax Kiitz., and he figured, for the first time, the oogonia. Later de Bary ('8I) referred to this figure when he renamed S. ferax, S. Thureti. In 1857 Pringsheim (57) contributed to the literature the description of S. monoica with excellent figures; other forms of Saprolegnia, those without antheridial branches, he considered as belonging to S. ferax. In 1873 he stated that further observation had convinced him that there was no true specific distinction between the forms with an antheridium on every oogonium and those in which the antheridia are almost or quite wanting. They differ, he says, "only in the relative number of antheridia." He therefore grouped all forms of Saprolegnia with round, pitted, many spored oogonia into the "ferax" group. In I88I, there appeared a paper by de Bary ('8I) in which he united S. monoica, S. torulosa, and S. Thureti (S. ferax) into a group which he called the ferax group. He had not yet distinguished S. mixta. In his description of S. monoica, de Bary followed Pringsheim, but added that in some cases the antheridial branches arise from hyphae remote from the oogonium, or, in other words, are not androgynous. 1 Contribution from the Botanical Laboratory of the LTniv. of Mich. No. I47. 307

There are no known reports of the occurrence of Saprolegnia australis Elliott since its initial isolation (Elliott, 1968). Saprolegnia australis is prevalent, however, in small streams feeding Bradley Creek, Wilmington, North Carolina. The most striking dissimiliarity of the present isolate (UNC-W No. WlOb, ATCC No. 32940) from the type species is sporangium size (FIGS. 1-4). Elliott reported the median primary sporangium length to be 40-80 tm, while those of W-lOb are 189-243 t/m (median 70%). Secondary sporangia in W-lOb, like the type species, usually are short and arise by internal proliferation; but in W-lOb secondary sporangia up to 600 tm in length are not uncommon at the tips of robust hyphae (FIG. 5). In 6-da-old cultures several sporangia exhibited dictyoid spore discharge, a characteristic not noted by Elliott. Although W-lOb is clearly an isolate of S. australis several aspects of its sexual morphology serve to broaden the species concept. Neither the antheridial branches no antheridia are persistent (FIGS. 6-7) while the reverse was true in Elliott's isolates. Fertilization tubes were found in three cases in W-lOb, (e.g., FIG. 8), but none were noted by Seymour (1970) in preserved slides of the type culture. O6spheres are variable in size as in Elliott's isolates, the smaller ones being produced by budding of large o6spheres (FIGS. 9-12). Mature subcentric o6spores of greatly varying sizes thus can be found in the same o6gonium (FIG. 7), but

A discomycete, Pyronema domesticum, was grown on medium containing 500 ppm 2,4-dichlorophenoxyacetic acid. Although many gametangia and apothecia appeared to develop normally on this medium, abnormalities were commonplace. Abnormalities included a reduction in the total number of ascogonia and antheridia formed in a gametangial cluster, malformed gametangia, fusion of the trichogyne with a structure other than the antheridium, failure for plasmogamy to be completed, the apomictic production of ascogenous hyphae, and the conversion of apothecia into sterile sclerotium-like structures. In addition, the 2,4-D caused a 2-5 day delay in the maturation of all apothecia.

Hyphae rather stout, branched, not long. About 40-45 mu in diameter at base and tapering to slender tips about I2 mu in diameter at base and tapering to slender tips about 12 mu in diameter. At maturity, the main hyphae strongly incline to segment into elongated sections with dense protoplasm, but the slender apical section is apt to remain almost empty (fig. I). Zo6sporangia almost cylindrical, inclined to be somewhat irregular and often opening by a bent papilla (fig. 2). Oogonia abundant, approximately spherical, without pits; completely covered with short, blunt irregular warts (fig. 3). Oogonia borne on the tips of very slender and delicate, but contorted lateral branches that are either simple, in which case there is but one oogonium (fig. 3), or more or less intricately branched, in which case there are a number of oogonia borne on the tips of the group of branches (figs. 4, 5, and 6). Oospores single or very rarely two in an oogonium; their diameter 15-23 mu, averaging about 20 mu. Antheridia absent from a good many o6gonia, when present, club-shaped; borne on the tips of branches from the same glomerulus and one or several on an o6gonium (fig. 5).

Ascospores of Spathulospora lanata form a short germ tube with a lobed appressorium from which the crustose thallus develops. Phialide- like antheridia originating on hairs give rise to spermatia t...

The early stages in the development of the oogonium and the antheridium of Sclerospora graminicola were found to be similar to those described for other members of the Peronosporales. A distortion,...

Very few fungi belonging to the Lagenidiaceae have been reported from North America. The two species which are the subject of this note were found attacking a large species of Cladophora in West Okoboji Lake, Dickinson County, Iowa, during the summer of 1925. In both instances a relatively small number of cells of the host were attacked, but the fungi are so distinctive as to leave no doubt of their identity in spite of the small number of individuals observed. These species have been known heretofore only from a few isolated localities in Europe. Myzocytium proliferum A. Schenk (Figs. 1, 2) was first de? scribed from Germany in 1857 as a Pythium. The following year Schenk established the genus Myzocytium to contain it. It has since been noted from several European localities on various filamentous green algae and desmids. The primitive mycelial filament breaks up into a chain of bead-like cells, some of which function as zoosporangia, others as antheridia or oogonia (Fig. 1, a). The discharge of zoospores was not observed in the Iowa material, but the empty sporangia occurring in the same chains of cells as the oogonia and antheridia are striking and unmistakable.

Pythium dimorphum, a new species, is characterized by oogonia partially to completely covered with blunt irregularly spaced projections averaging 3 / in length and aplerotic to nearly plerotic oospores averaging 30 / diam. Antheridia may be hypogynous or monoclinous but are frequently absent. Prominent ovoid to elongate thin-walled, spherical chlamydospores averaging 64 L in diam with dark contents are a distinguishing feature of this fungus. Ovoid or club-shaped sporangia, averaging 28 X 54 1A, are present.

The development of the sexual organs of Achlya flagellata is similar to that in other members of the genus. A single mitotic division occurs within the oogonium and antheridium. The chromosome numb...