ETIOLOGY AND DEVELOPMENT OF HYPERPLASIA INDUCED BY STREBLONEMA SP. (PHAEOPHYTA) ON MEMBERS OF THE LAMINARIALES (PHAEOPHYTA)1

Filaments of Streblonema sp. isolated from hyperplasia (galls) on Nereocystis luetkeana (Mert.) Post. et Rupr. induced similar gall growths when inoculated on young sporophytes of Nereocystis luetkeana, Macrocystis integrifolia Bory, and Laminaria japonica Aresch. Filaments were irregularly branched and uniseriate with cells 5–8 μm in diameter and 10–30 μm long. Growth under varied cultured conditions produced unilocular sporangia. Zoospores released from the sporangia germinated into identical filaments which also formed unilocular sporangia. Gall tissue originated from the innermost cells of the epidermal meristematic zone. When infected these cells divided in an irregular and unorganized manner. The resulting structure was a pronounced departure from normal morphology.     

ATRACTOMORPHA ECHINATA GEN. ET SP. NOV., A NEW ANISOGAMOUS MEMBER OF THE SPHAEROPLEACEAE (CHLOROPHYCEAE)1,2

Atractomorpha echinata gen. et sp. nov. is described from isolates derived from zygotes present in a dry soil sample obtained from Texas. The new genus is distinguished from Sphaeroplea primarily by its pattern of vegetative growth. While Sphaeroplea is distinctly filamentous with numerous coenocytic cells uniseriately arranged, Atractomorpha grows as individual, multinucleate, spindle-shaped cells with sharply pointed extremities. Such cells may vary considerably in length (25–6000 μm, or more) and normally lack septa. In young, rapidly growing cultures the cells often attain lengths of 300–500 μm, but rarely exceed 1800 μm. The new species is further characterized by: (1) the regular formation of biflagellate zoospores in asexual reproduction, (2)anisogamy (occasionally oogamy) and (3) the size and ornamentation of its zygotes. Variations in vegetative morphology are discussed as are conditions for obtaining gametogenesis.     

THE SPORANGIUM OF HORNEOPHYTON LIGNIERI (RHYNIOPHYTINA)

Numerous sporangia of Horneophyton lignieri from the Rhynie Chert locality in Scotland have been studied. The sporangia are branched, with two to four columellate lobes of varying length, and a continuous sporogenous zone or cavity occurs among the lobes. Unbranched sporangia, generally thought to be the typical form for the plant have not been found, and their presence is not established. Although not definitely proven, evidence suggests that the sporangia opened by means of a small apical pore or stoma. An area of thick-walled cells at the apex of each sporangial lobe probably played some role in this opening. Radial, trilete, azonate spores ranging from 39–49 μm in diam, with curvaturae perfectae are produced most commonly in tetrahedral tetrads and occasionally in isobilateral tetrads. Matters of spore preservation and possible ornamentation are discussed. The branched sporangia of this genus are unique among bryophytes and vascular plants and provide some evidence that certain synangia may have arisen from a single sporangium rather than from multiple sporangia borne singly at the tips of ultimate branches.     

Protozoans—the first food of larval herring (Clupea harengus L.)?

In short-run experiments herring larvae at the end of the yolk sac stage (S_L 6.5 to 8.5 m) were fed with maize and potato starch to investigate the effect of particle size on food selection. About 20% of the larvae ingested these particles during the experiments. In the case of maize starch (3 to 26 μm grain size) the size classes from 14 to 25 μm and in the case of potato starch (5 to 80 μm) the size classes larger than 29 μm were preferred. The highest numbers of ingested grains per larva were 150 maize starch grains and 57 potato starch grains. The selective uptake of these size classes leads to the conclusion that planktonic organisms in this size range—in other words mostly protozoans—may play an important role as a first food source of herring larvae.     

腾格里沙漠草方格固沙林土壤颗粒组成、分形维数及其对土壤性质的影响

为了明确草方格人工固沙造林植被恢复过程中土壤颗粒组成、分形维数及对土壤理化性质的影响,以腾格里沙漠东南缘2016年(1 a)、2013年(4 a)和1987年(30 a)草方格固沙林为研究样地,以周围流动沙地为对照(CK),研究了草方格固沙造林后植被恢复过程中土壤颗粒组成、分形维数及与土壤理化性质的作用关系.结果表明: 100～250、250～500 μm土壤颗粒含量较高,分别为42.5%～80.1%、12.5%～42.2%;50～100 μm土壤颗粒含量居中,为0.2%～20.8%;<2和2～50 μm的土壤颗粒含量次之,分别在0～1.3%和0～22.7%;而500～1000 μm的土壤颗粒含量较低,在0.3%以下.<2和2～50 μm土壤颗粒仅在30 a固沙林有分布;50～100 μm土壤颗粒分布为30 a最高,4 a和1 a居中,而CK最低;100～250 μm土壤颗粒分布依次为4 a>1 a>CK>30 a;250～500 μm土壤颗粒分布为CK>1 a>4 a>30 a;但500～1000 μm土壤颗粒在各样地分布均较少,且不同样地之间无显著差异.研究区土壤颗粒分形维数为0.54～2.59,并且不同样地间存在显著差异,表现为30 a最高,4 a与1 a居中,而CK最低.土壤颗粒分形维数与土壤黏粒、粉粒、极细砂粒含量呈极显著正相关,而与土壤中砂粒呈极显著负相关.土壤颗粒分形维数与土壤电导率、有机碳、全氮和碳氮比均呈极显著正相关,而与土壤pH和含水量无相关性.土壤中<2、2～50、50～100 μm颗粒与土壤电导率、有机碳、全氮和碳氮比均呈极显著正相关,而250～500 μm土壤颗粒与上述4个土壤指标和土壤含水量呈显著负相关.500～1000 μm土壤颗粒与土壤含水量亦呈极显著负相关.在腾格里沙漠东南缘地区利用草方格进行人工固沙植被建设,可有效促进土壤颗粒细粒化,长期演变导致土壤黏粒和粉粒及土壤分形维数显著增加,促使土壤有机碳和全氮含量提高,有利于土壤理化性质改善和促进沙漠化治理.     

Pythium sukuiense, a new species from undisturbed natural forest in Taiwan

A new species, Pythium sukuiense, was isolated from an undisturbed natural forest in northern Taiwan. The fungus produces sporangia indistinguishable from hyphae and very small oogonia and oospores. Oogonia were smooth and terminal or intercalary and attached with a single antheridium. Oospores were aplerotic, with an average size of only 11 μm.     

Pollen morphology of andruris japonica (triuridaceae)

Pollen morphology of Andruris japonica (Triuridaceae) was investigated by light and electron microscopy. The pollen is monosulcate and has a size of 22–25 μm × 25–28 μm in polar view. In the non-apertural region the exine has gemmate to nearly verrucate protrusions of 0.4–0.5 μm in diameter and 0.3–0.5 μm in height, and a foot layer of 0.4–0.5 μm in thickness. The sporoderm of the apertural region has large gemmae of 0.7–0.8 μm in diameter and 0.6–0.7 μm in height, with a thin foot layer of 0.1 μm thickness.     

THE DEVELOPMENT AND CYTOLOGY OF THE EPIBIOTIC PHASE OF PHYSODERMA PULPOSUM

Lingappa , Yamuna . (U. Michigan, Ann Arbor.) The development and cytology of the epibiotic phase of Physoderma pulposum. Amer. Jour. Bot. 46(3) : 145-150. Illus. 1959.—Physoderma pulposum, a chytrid parasite on Chenopodium album L. and Atriplex patula L., has a zoosporangial epibiotic phase. The latter consists of extramatrical sporangia and intramatrical bushy rhizoids, both enclosed in large protruding galls. The sporangia are subspherical, up to 350μ in diameter, and may produce hundreds of planospores. If planospores settle on the host surface, they develop narrow germ tubes which penetrate the epidermal cells and develop into rhizoids. The planospore body, however, remains on the host surface and develops into a mature epibiotic sporangium in about 20-25 days at 16°C., 12-15 days at 20-25°C., or 6-8 days at 30°C. During development, its nucleus and daughter nuclei divide mitotically with intranuclear spindles until the sporangium contains several hundred nuclei. This is followed by progressive cleavage which delimits the planospore rudiments. When mature sporangia are placed in fresh water, the planospores are quickly formed within 1 hr. at 25°C. and begin to swarm within the sporangia. They escape in large numbers through an opening formed by the deliquescence of a papillum in the sporangial wall. The planospores are subspherical or elongate, 3-5 × 4-6 μ, and each has an eccentric orange-yellow refractive globule and a flagellum 18-22 μ in length. The electron micrographs of the flagella indicate that the flagella are absorbed from tip backward during encystment of the planospores. By periodic inoculation of the host plants with planospores from epibiotic sporangia, as well as from germinating resting sporangia, generation after generation of epibiotic sporangia have been obtained for 4 years. This proves the existence of a eucarpic, epibiotic, ephemeral zoosporangial phase in P. pulposum. Field observations on the duration and sequence of development of the fungus indicate that the endobiotic resting sporangial phase always follows the epibiotic phase. The results of infection experiments also indicate that the epi- and endobiotic phases belong to one and the same fungus, P. pulposum.     

First Report of Peronospora belbahrii on Sweet Basil in Baja California Sur,México

In Baja California Sur, Mexico, a foliar disease occurred on sweet basil which seriously affected its quality and yield. The most common symptoms were yellowing and necrosis on leaves, caused by a downy mycelium growth on the lower leaf surface. Symptomatic leaves from two sampling sites were collected for morphological studies and molecular analysis of pathogen DNA. Based on morphological characteristics (sporangiophore size of 240–530 × 7–11 μm, branches of 5–8 order and a sporangia size of 27–31 × 21–25 μm) and molecular analysis (the GenBank blast of the PCR assays showed unique rDNA sequence data with 99% similarity to P. belbahrii), the pathogen was identified as Peronospora belbahrii, the causal agent of basil downy mildew. This is the first report of P. belbahrii affecting sweet basil in Mexico.     

STUDIES OF PALEOZOIC MARATTIALEANS: THE MORPHOLOGY AND PHYLOGENETIC POSITION OF EOANGIOPTERIS GOODII SP. N.

Eoangiopteris goodii sp. n. is described from Upper Pennsylvanian coal balls from Ohio (Shade locality) containing isolated pecopterid pinnules approx. 7 × 9 mm that bear up to 20 linear synangia on the lower surface. The synangia extend at right angles from the midrib to the downturned pinnule margins and measure 2.0–3.5 mm in length. Individual synangia are compact and are composed of 10–19 sporangia that have their bases embedded in an elongate parenchymatous pad. In longitudinal section sporangia measure 0.4 × 2.0 mm and have acute elongate, curved apices. Spores average 70 μm in diam and are most similar to the dispersed spore genus Verrucosisporites. Eoangiopteris goodii differs from the generitype E. andrewsii Mamay in its greater size, pinnule histology, and spore type. Sporangium wall complexity and spore type of the two presently known species of Eoangiopteris are considered to be at about the same evolutionary level as the more primitive species of Scolecopteris. Construction of the synangia in Eoangiopteris is different from that of Scolecopteris and indicates that at least two evolutionary lines are recognizable within the Pennsylvanian Marattiales.     

Effects of concentration,distance, and application methods of Altriset (Chlorantraniliprole) on eastern subterranean termite (Isoptera: Rhinotermitidae)

The effects of various concentrations, distance, and application methods of Altriset (Chlorantraniliprole) were investigated against one of the most destructive termites, the eastern subterranean termite, Reticulitermes flavipes Kollar. Three laboratory experiments were conducted. First, we examined the concentration effect of treating the soil contiguously to established foraging tunnels at a fixed 1 m distance. The results demonstrated 100% termite control in 19 d posttreatment at 100 and 50 μg/g and 27% termite mortality at 25 μg/g. Second, we tested the distance effect of the soil treatment (2 and 4 m) on the efficacy of Altriset to the satellite termite populations at a fixed 50 μg/g concentration. This resulted in 100% termite control in 22 d posttreatment at both 2 and 4 m. Third, we examined the effect of differing application methods using 12.5 and 25 μg/g prior to the establishment of foraging tunnels at a fixed 1m distance. This illustrated 100% termite control in 9 d posttreatment at 25 μg/g and 12 d posttreatment at 12.5 μg/g. The third experiment demonstrated soil treatments that were applied prior to termite tunnel establishment had greater efficacy than applications made post tunnel construction. Our results provide a comprehensive understanding about the efficacy of Altriset treatments on eastern subterranean termites.     

SPORANGIAL STRUCTURE AND ZOOSPOROGENESIS IN CHORDA TOMENTOSA (LAMINARIALES)1,2,3

Members of the genus Chorda represent the simplest form of sporophyte in the order Laminariales. The present study deals with reproduction in Chorda tomentosa, involving the initiation, growth, and structure of the sporangium and the process of zoosporogenesis. The simple tube-like sporophyte of Chorda tomentosa grows in diameter by means of repeated anticlinal divisions in a superficial meristematic layer known as the meristoderm. The onset of reproduction is marked by the conversion of the meristoderm from contributing cells to the vegetative plant body to producing 2 new cell types: paraphyses and sporangial mother cells. At the time of initiation, sporangial mother cells are crescent shaped and possess a densely staining cytoplasm. Sporangial mother cells increase in size, become ellipsoid, decrease in staining density, and undergo meiosis. After meiosis, sporangia increase in size while their nuclei undergo successive cycles of synchronous mitotic divisions. Sporangia increase to a maximum length of 120 μ;m at which time they possess the characteristic “cap” found in all members of the order studied thus far. At this stage the protoplast of the sporangium is organized into a peripheral layer of nucleus-chloroplast pairs and a central region of vacuoles. Cleavage furrows begin to form at the cell membrane and are met by furrows developing in the interior of the cytoplasm resulting in the division of the entire protoplast into separate units. Each unit is an individual zoospore. The biflagellate zoospores contain a nucleus, one chloroplast with eyespot, perinuclear Golgi, and several bodies of presumed storage carbohydrate. The occurrence of a small population of early developing sporangia is described. In essential details, the origin, development, and structure of sporangia in Chorda tomentosa are identical to all earlier observations in the Laminariales.     

THREE NEW BENTHIC SPECIES OF PROROCENTRUM (DINOPHYCEAE) FROM BELIZE: P. NORRISIANUM SP. NOV., P. TROPICALIS SP. NOV., and P. RETICULATUM SP. NOV.1

Three new benthic, photosynthetic dinoflagellate species, Prorocentrum norrisianum, Prorocentrum tropicalis, and Prorocentrum reticulatum, from floating detritus and coral rubble of Central America are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, thecal plate ornamentation, and architecture of the periflagellar area and intercalary band. Cells of P. norrisianum are ovate with a cell size of 20–25 μm long and 13–16 μm wide. The theca is delicate, its surface smooth, pores species specific with 95 to 105 pores per valve. Pores are round with a diameter of about 0.1 μm. The periflagellar area is V-shaped, located on the right valve in a shallow depression. It has no ornamentation. The flagellar and auxiliary pores are unequal in size. The intercalary band is smooth. Prorocentrum tropicalis cells are ovoid, 50–55 μm long and 40–45 μm wide in valve view with maximum width behind the middle region, narrow at the anterior end. The periflagellar area, situated in the right valve, is a V-shaped wide triangle with a deeply indented depression; the left valve exhibits a flat ridge. The periflagellar area is unornamented, and the flagellar and auxiliary pores are unequal in size. The valve surface is rugose with evenly distributed valve poroids. Each poroid appears to have a small dome in the center. The intercalary band is rimlike around the cell margin, granulated, and horizontally striated. Prorocentrum reticulatum cells are oblong in valve view; cells are 55–60 μm long and 40–45 μm wide. Thecal surface is reticulated; it is composed of a labyrinth of ridges with alternating depressions that vary in size and shape. Each depression has a narrow, oblong-kidney-shaped opening about 0.6 μm long. The periflagellar area is a deep, V-shaped triangle. The right valve of P. reticulatum is excavated, and contains a large flagellar pore and a smaller auxiliary pore surrounded by a narrow apical collar. The left valve margin exhibits a curved flat ridge. The intercalary band is smooth.     

Distribution of soil fractions and location of soil bacteria in a vertisol under cultivation and perennial grass

Effects of soil management on soil characteristics were investigated on the rhizosphere (RPP) and the nonrhizosphere (NRPP) soil of a re-grass vertisol underDigitaria decumbens and in the soil under continuous cultivation (CC). A low energy technique allowed to separate eight size and density fractions, including macro- and micro-aggregates while preserving soil bacteria. Organic C and N, microbial biomass C and the number of total bacteria (AODC) and ofAzospirillum brasilense and their distribution were determined in soil fractions isolated from the CC, NRPP and RPP soils. Soil macroaggregates (>2000 m) were similarly predominant in the NRPP and RPP soils when the dispersible clay size fraction (<2 m) respresented more than 25% of the CC soil mass. The main increase of C content in RPP originated from the macroaggregates (> 2000 m) and from the root fraction, not from the finer separates. The proportion of organic C as microbial biomass C revealed the low turnover of microbial C in the PP situations, especially in the clay size fraction of the NRPP soil. A common shift of AODC toward the finer separates from planted soils (CC and RPP) revealed the influence of living plants on the distribution of soil bacteria. The relative abundance ofA. brasilense showed the presence of the active roots ofDigitaria in the macroaggregates and their contact with the dispersible clay size fraction of the rhizosphere soil.     

Laminarionema elsbetiae gen. et sp. nov. (Ectocarpales, Phaeophyceae), a new endophyte in Laminaria sporophytes

Laminarionema elsbetiae gen. et sp, nov, (Ectocarpaceae, Ectocarpales. Phaeophyceae), a new endophyte of Laminaria japonica Areschoug (Laminariales, Phaeophyceae), is described from Muroran. Hokkaido, Japan. Laminarionema elsbetiae grows in the host tissues forming networks in the epidermal and subcortical layers as well as penetrating into the cortical and medullary layers. Only phaeophycean hairs emerge from the surface of the host tissue. No reproductive cells were found in field material. However, under host-free culture the species formed three morphologically different reproductive structures. Macrosporangia containing a single large motile spore were formed under long and short day conditions below 20°C, transformed from vegetative cells, conical to elongated in shape, 50–75 μm in length and ca. 10 μm in diameter. Microsporangia were linear to lanceolate, sometimes branched, formed under long and short day conditions below 15°C. Unilocular sporangia were more or less irregular in shape, formed under short day conditions of 5–15°C, 60–75 μm in length and 40–45 μm in diameter. Sexual fusion between macro- and microspores was not seen. In mixed cultures of L. elsbetiae with young sporophytes of L Japonica Areschoug as well as Saccorhiza dermatodea (de la Pylaie) J. Agardh, L elsbetiae infected both hosts, grew in the same manner as in natural hosts, and formed macrosporangia between host epidermal cells.     

Microscale heterogeneity of the soil nitrogen cycling microbial functional structure and potential metabolism

Soil aggregates, with complex spatial and nutritional heterogeneity, are clearly important for regulating microbial community ecology and biogeochemistry in soils. However, how the taxonomic composition and functional attributes of N-cycling-microbes within different soil particle-size fractions under a long-term fertilization treatment remains largely unknown. Here, we examined the composition and metabolic potential for urease activity, nitrification, N₂O production and reduction of the microbial communities attached to different sized soil particles (2000–250, 250–53 and <53 μm) using a functional gene microarray (GeoChip) and functional assays. We found that urease activity and nitrification were higher in <53 μm fractions, whereas N₂O production and reduction rates were greater in 2000–250 and 250–53 μm across different fertilizer regimes. The abundance of key N-cycling genes involved in anammox, ammonification, assimilatory and dissimilatory N reduction, denitrification, nitrification and N₂-fixation detected by GeoChip increased as soil aggregate size decreased; and the particular key genes abundance (e.g., ureC, amoA, narG, nirS/K) and their corresponding activity were uncoupled. Aggregate fraction exerted significant impacts on N-cycling microbial taxonomic composition, which was significantly shaped by soil nutrition. Taken together, these findings indicate the important roles of soil aggregates in differentiating N-cycling metabolic potential and taxonomic composition, and provide empirical evidence that nitrogen metabolism potential and community are uncoupled due to aggregate heterogeneity.     

Effect of soil aggregate size on methanogenesis and archaeal community structure in anoxic rice field soil

In anoxically incubated slurries of Italian rice field soil, CH(4) production is initiated after a lag phase during which ferric iron and sulfate are reduced. The production of CH(4) was affected by the size of soil aggregates used for the preparation of the soil slurry. Rates of CH(4) production were lowest with small aggregates (<50 and 50-100 μm), were highest with aggregates of 200-2000 μm size and were intermediate with aggregates of 2000-15000 μm size. The different amounts of CH(4) accumulated were positively correlated to the concentrations of acetate, propionate and caproate that transiently accumulated in the slurries prepared from different aggregate sizes and also to the organic carbon content. The addition of organic debris that was collected from large-size aggregates to the aggregate size fractions <200 and <50 μm resulted in an increase of CH(4) production to amounts that were comparable to those measured in unamended aggregates of 200-2000 μm size, indicating that CH(4) production in the different aggregate size fractions was limited by substrate. The distribution of archaeal small-subunit rRNA genes in the different soil aggregate fractions was analyzed by terminal restriction fragment length polymorphism which allowed seven different archaeal ribotypes to be distinguished. Ribotype-182 (consisting of members of the Methanosarcinaceae and rice cluster VI), ribotype-389 (rice cluster I and II) and ribotype-820 (undigested DNA, rice cluster IV and members of the Methanosarcinaceae) accounted for >20, >30 and >10% of the total, respectively. The other ribotypes accounted for <10% of the total. The relative quantity of the individual ribotypes changed only slightly with incubation time and was almost the same among the different soil aggregate fractions. Ribotype-389, for example, slightly decreased with time, whereas ribotype-182 slightly increased. At the end of incubation, the relative quantity of ribotype-182 seemed to be slightly higher in soil fractions with larger than with smaller aggregates, whereas it was the opposite with ribotype-80 (Methanomicrobiaceae) and ribotype-88 (Methanobacteriaceae). Ribotype-280 (Methanosaetaceae and rice cluster V), ribotype-375 (rice cluster III), ribotype-389 and ribotype-820, on the other hand, were not much different among the different soil aggregate size fractions. However, the differences were not significant relative to the errors encountered during the extraction of polymerase chain reaction (PCR)-amplifiable DNA from soil. In conclusion, soil aggregate size and incubation time showed a strong effect on the function but only a small effect on the structure of the methanogenic microbial community.     

Two New Species of Eimeria from Colubrid Snakes in Iowa*

SYNOPSIS. Oocysts of Eimeria natricis sp. n. and Eimeria sipedon sp. n. were isolated from 2 Northern Water Snakes, Natrix sipedon sipedon (Linnaeus), in Iowa. Oocysts of E. natricis were elongate, slightly ovoid, averaging in size 32.3 × 17.5 μm; sporocysts averaged 15.7 × 8.2 μm. Oocysts of E. sipedon were broadly ovoid averaging in size 18.0 × 15.9 μm; sporocysts averaged 12.0 × 7.4 μm. In both species, sporocyst residua were present, but micropyles, polar granules and oocyst residua were lacking.     

New Insights in the Life Cycle and Epidemics of Phytophthora porri on Leek

White tip, caused by Phytophthora porri, is a devastating disease in the autumn and winter production of leek (Allium porrum) in Europe. This study investigated the disease cycle of P. porri in laboratory and field conditions. Oospores readily germinated in the presence of non‐sterile soil extract at any temperature between 4 and 22°C, with the formation of sporangia which released zoospores. The zoospores survived at least 7 weeks in water at a temperature range of 0 till 24°C. Microscopic examinations revealed that zoospores encysted and germinated on the leek leaf surface and hyphae entered the leaf directly through stomata or by penetrating via appressoria. Oospores were formed in the leaves within 6 days, while sporangia were not produced. By monitoring disease progress in fields with a different cropping history of leek, it could be deduced that P. porri survives in soil for up to 4 years. Disease progress during three consecutive years was correlated with average daily rainfall in the infection period. Disease incidence on leek was reduced when rain splash was excluded by growing the plants in an open hoop greenhouse. Based on these findings, we propose a disease cycle for P. porri in which oospores germinate in puddles, and zoospores reach the leaves by rain splash and survive in water in the leaf axils, from where they infect the plant by direct penetration or via stomata. When conditions become unfavourable, oospores are produced in the leaves which again reach the soil when leaves decay. Secondary spread of the disease by sporangia does not seem to be important.     

Ultrastructure and Description of a Fungus-Feeding Amoeba,Trichamoeba mycophaga n. sp. (Amoebidae,Amoebea), from Australia1

ABSTRACT. An amoeba isolated from a wheatfield and a forest soil in Australia has been identified as Trichamoeba mycophaga n. sp. Trophozoites of this amoeba are palmate to elongate and measure 45–136 μm in length and 25–94 μm in width. Amoebae in continuous locomotion may be limax with a villous-bulb uroid. Both the lobose pseudopodia and the advancing margin of a limax trophozoite bear an ectoplasmic crescent. The plasma membrane is coated with an electron-dense amorphous layer ca. 100 nm thick. Endoplasm is granular with elongate to bipyramidal crystals and contains bacterial endosymbionts. Trophozoites have a single, spherical to oval nucleus, 4–10 μm in diameter, which contains a centrally located, spherical to oval nucleolus, 2.8–5.0 μm in diameter. The nucleoplasm contains aggregations of filaments distributed radially within the nuclear membrane. Cysts are 21–60 μm in diameter, with ecto- and endocyst walls separated by an amorphous layer.