Ultrastructural Study and Description of Ovavesicula popilliae N. G., N. Sp. (Microsporida: Pleistophoridae) from the Japanese Beetle,Popillia japonica (Coleoptera: Scarabaeidae)1

A new genus and species of microsporidia, Ovavesicula popilliae n. g., n. sp., is described from the Japanese beetle, Popillia japonica, on the basis of studies by light and electron microscopy. Parasite development primarily occurs within the Malpighian tubules of larvae, and spores are formed in a sporophorous vesicle. Meronts have diplokaryotic nuclei, develop in direct contact with the host cell cytoplasm, and divide by binary fission. Sporonts have unpaired nuclei, develop within a thick sporophorous vesicle, and undergo synchronous nuclear divisions producing plasmodia with 2, 4, 8, 16, and 32 nuclei. Cytokinesis of sporogonial plasmodia does not occur until karyokinesis is complete with 32 nuclei. Intact sporophorous vesicles are ovoid, containing numerous secretory products, and are surrounded by a persistent two-layered wall. The uninucleate spores are regularly formed in groups of 32, and the polar tube in each has six coils.     

Life Cycle of Culicosporella lunata (Hazard & Savage, 1970) Weiser, 1977 (Microspora) as Revealed in the Light Microscope with a Redescription of the Genus and Species1

Light microscopy studies of Culicosporella lunata (Hazard & Savage), a parasite of the mosquito Culex pilosus (Dyar & Knab), revealed two sporogonial sequences. One sequence begins with diplokaryotic meronts that undergo repeated nuclear divisions to produce sporogonial plasmodia with nuclei in diplokaryotic arrangement. These plasmodia form rosette-like clusters of sporoblasts during incomplete cytokinesis and, eventually, binucleate spores. These spores initiate infections in healthy larvae when they ingest spores. The second sequence begins with diplokaryotic meronts that undergo karyogamy and meiosis to form Thelohania-like sporonts and haploid spores. Anomalies are often observed in these sporonts which result in aberrant spores, usually fewer than eight, in an accessory (pansporoblastic) membrane. Normal haploid spores are morphologically similar to those of species of Amblyospora. The genus and the type species are redefined based on new information presented here and it and the type species are placed in the family Amblyosporidae.     

Description of Chytridiopsis Trichopterae N. Sp. (Microspora, Chytridiopsidae), A Microsporidian Parasite of the Caddis Fly Polycentropus Flavomaculatus (Trichoptera, Polycentropodidae), With Comments On Relationships Between the Families Chytridiopsidae and Metchnikovellidae

ABSTRACT. The microsporidium Chytridiopsis trichopterae n. sp., a parasite of the midgut epithelium of larvae of the caddis fly Polycentropus flavomaculatus found in southern Sweden, is described based on light microscopic and ultrastructural characteristics. All life cycle stages have isolated nuclei. Merogonial reproduction was not observed. the sporogony comprises two sequences: one with free spores in parasitophorous vacuoles, the other in spherical, 5.6-6.8 μm wide, sporophorous vesicles which lie in the cytoplasm. the free sporogony yields more than 20 spores per sporont. the vesicle-bound sporogony produces 8, 12 or 16 spores. the envelope of the sporophorous vesicle is about 82 nm thick and layered. the internal layer is the plasma membrane of the sporont; the surface layer is electron dense with regularly arranged translucent components. Both spore types are spherical. They have an ～ 35-nm thick spore wall, with a plasma membrane, an electron-lucent endospore, and an ～ 14-nm thick electron-dense exospore. the polar sac is cup-like and lacks a layered anchoring disc. the polar filament is arranged in two to three isofilar coils in the half of the spore opposite the nucleus. the coupling between the polar sac and the polar filament is characteristic. the surface of the polar filament is covered with regularly arranged membraneous chambers resembling a honeycomb. There is no polaroplast of traditional type. the cytoplasm lacks polyribosomes. the nucleus has a prominent, wide nucleolus. the two spore types have identical construction, but differ in dimensions and electron density. Free living spores are about 3.2 μm wide, the diameter of the polar filament proper is 102-187 nm, the chambers of the honeycomb are 70-85 nm high, and the polar sac is up to 425 nm wide. Living spores in the vesicle-bound sporogony are about 2.1 μm wide, the polar filament measures 69-102 nm, the chambers of the honeycomb are about 45 nm high, and these spores are more electron dense. Comparisons of cytology (especially the construction of the spore wall and the polar filament and associated structures) and life cycles reveal prominent differences among the Chytridiopsis-like microsporidia, and close relationships between the families Chytridiopsidae and Metchnikovellidae.     

Paranucleospora theridion n. gen., n. sp. (Microsporidia,Enterocytozoonidae) with a Life Cycle in the Salmon Louse (Lepeophtheirus salmonis,Copepoda) and Atlantic Salmon (Salmo salar)

ABSTRACT. Paranucleospora theridion n. gen, n. sp., infecting both Atlantic salmon (Salmo salar) and its copepod parasite Lepeophtheirus salmonis is described. The microsporidian exhibits nuclei in diplokaryotic arrangement during all known life‐cycle stages in salmon, but only in the merogonal stages and early sporogonal stage in salmon lice. All developmental stages of P. theridion are in direct contact with the host cell cytoplasm or nucleoplasm. In salmon, two developmental cycles were observed, producing spores in the cytoplasm of phagocytes or epidermal cells (Cycle‐I) and in the nuclei of epidermal cells (Cycle‐II), respectively. Cycle‐I spores are small and thin walled with a short polar tube, and are believed to be autoinfective. The larger oval intranuclear Cycle‐II spores have a thick endospore and a longer polar tube, and are probably responsible for transmission from salmon to L. salmonis. Parasite development in the salmon louse occurs in several different cell types that may be extremely hypertrophied due to P. theridion proliferation. Diplokaryotic merogony precedes monokaryotic sporogony. The rounded spores produced are comparable to the intranuclear spores in the salmon in most aspects, and likely transmit the infection to salmon. Phylogenetic analysis of P. theridion partial rDNA sequences place the parasite in a position between Nucleospora salmonis and Enterocytozoon bieneusi. Based on characteristics of the morphology, unique development involving a vertebrate fish as well as a crustacean ectoparasite host, and the results of the phylogenetic analyses it is suggested that P. theridion should be given status as a new species in a new genus.     

The ultrastructure of three microsporidia from winter moth,Operophtera brumata (L.), and the establishment of a new genus Cystosporogenes n.g. for Pleistophora operophterae (Canning, 1960)

Summary The ultrastructure of three species of microsporidia in winter moths, Operophtera brumata (L.), has been used to consolidate taxonomic assessments previously based on light microscopy. The characters formerly used to assign Nosema operophterae Canning, 1960 to a new genus Orthosoma Canning, Wigley & Barker, 1983, namely that the nuclei are isolated and that sporoblasts are separated from ribbon-shaped multinucleate (2, 4, 8 or rarely 12 nuclei) sporonts, were upheld at the ultrastructural level. Development was in contact with the cell cytoplasm but all stages, which must have included meronts, had an electron dense surface coat. Nosema wistmansi Canning, Wigley & Barker, 1983, was found to be ultrastructurally typical of the genus Nosema Naegeli, 1857. An unusual feature of this species was the close association of cysternae of host endoplasmic reticulum with the surface of meronts, an association lost in sporogony. Pleistophora operophterae (Canning, 1960) has been transferred, on ultrastructural criteria, to a new genus Cystosporogenes n.g. Nuclei are isolated; all stages develop in a vesicle bounded by an envelope of enigmatic origin; this envelope persists around the spores as a sporophorous vesicle; division of the sporont within this vesicle is by budding and the number of sporoblasts, and therefore spores, is variable up to about 60.Microsporidia which undergo multisporous sporogony in sporophorous vesicles are now distributed among seven genera. These are: Glugea Thélohan, 1891; Pleistophora Gurley, 1893; Pseudopleistophora Sprague, 1977; Vavraia Weiser, 1977; Baculea Loubès & Akbarieh, 1978; Polydispyrenia Canning & Hazard, 1982 and Cystosporogenes n.g. New genera would appear to be needed for Pleistophora sp. of Sandars & Poinar (1976) and Pleistophora sp. of Percy, Wilson & Burke (1982). ac]19840404     

Fine structure and sporogonic development of a Vavraia sp. (Microsporida: Pleistophoridae) in the biting midge Culicoides edeni (Diptera: Ceratopogonidae)

A microsporidium with ultrastructural characteristics of the genus Vavraia was found in the fat body of an adult specimen of Culicoides edeni (Diptera: Ceratopogonidae) collected in northern Florida. The sporogonial stages developed within sporophorous vesicles, which contained variable numbers of oval spores at maturity. The wall of the sporophorous vesicle was composed of two electron-dense outer layers and an electron-lucent intermediate layer. Sporonts contained haplokaryotic nuclei and divided by rosette formation. Mature spores had anisofilar polar filaments and measured 3.8 +/- 0.28 microns in length and 2.2 +/- 0.16 microns in width in thick sections of resin-embedded material. This is the first report of a Vavraia sp. from a species of Culicodes.     

Napamichum cellatum N. Sp. (Microspora, Thelohaniidae), a New Parasite of Midge Larvae of the Genus Endochironomus (Diptera, Chironomidae) in Sweden

ABSTRACT The new microsporidium, Napamichum cellatum, a parasite of the adipose tissue of midge larva of the genus Endochironomus in Sweden, is described based on light microscopic and ultrastructural characteristics. Plurinucleate Plasmodia with nuclei arranged as diplokarya divide, probably by plasmotomy, producing a small number of diplokaryotic merozoites. The number of merogonial cycles is unknown. Each diplokaryotic sporont yields eight monokaryotic sporoblasts in a thin-walled, more or less fusiform sporophorous vesicle. A small number of multisporoblastic sporophorous vesicles were observed, in which a part of the sporoblasts were anomalous. The sporogony probably begins with a meiotic division. The mature spores are slightly pyriform. Fixed and stained spores measure 2.1-2.4 × 3.7-4.5 μm. The five-layered spore wall is of the Napamichum type. The polar filament is anisofilar with seven to eight coils (142-156 and 120 nm wide). The angle of tilt is 55-65°. The polaroplast has an anterior lamellar and a posterior tubular part. The granular, tubular and crystal-like inclusions of the episporontal space disappear more or less completely when the spores mature. The crystal-like inclusions are prominent in haematoxylin staining, but not visible with the Giemsa technique. The microsporidium is compared to other octosporoblastic microsporidia of midge larva and to the species of the genera Chapmanium and Napamichum.     

Unikaryon polygraphi sp.n. (Protista, Microspora): a new pathogen of the four-eyed spruce bark beetle Polygraphus poligraphus (Col., Scolytidae)

The microsporidium Unikaryon polygraphi sp.n., a pathogen of Polygraphus poligraphus in Austria is described based on light microscopic and ultrastructural characteristics. All life stages have isolated nuclei. Sporogony ends with uninucleate single sporoblasts and spores. Mature oval spores measure 2.5–3.0 μm × 1.0–1.5 μm. The larger spores (3 × 1.5 μm) belong to the `early spore type' with a polar filament coiled in five turns and the smaller spores (2.5 × 1 μm) with polar filament coiled in 6/7 turns belong to the `environmental spore type'. Columnar cells of the midgut, longitudinal and circular muscles and the secretory part of Malpighian tubules of adult beetles are infected. Mature spores are excreted together with the faeces.     

Unikaryon phyllotretae sp. n. (Protista,Microspora), a new microsporidian pathogen of Phyllotreta undulata (Coleoptera; Chrysomelidae)

The microsporidium Unikaryon phyllotretae sp. n., a new pathogen of Phyllotreta undulata, is described based on light microscopic and ultrastructural characteristics. Microscopic examination of parasitized individuals revealed two types of spores. The majority of the spores were of the first type, which are oval and measured 2.74±0.17×1.93±0.17 μm when fresh. Fresh spores of the second type (very rare) are elongated and measured 4.39±0.18×1.61±0.20 μm. All life stages have single nuclei. Sporogony ends with uninucleate single sporoblasts and spores. The spores were only observed in Malpighian tubules. The isofilar polar filament of the parasite has six to eight coils, and a well-developed polaroplast was of the lamellated type, with closely packed anterior lamellae and loosely packed posterior lamellae.     

The Light and Electron Microscopic Cytology of Janacekia adipophila N. Sp. (Microspora, Tuzetiidae), a Microsporidian Parasite of Ptychoptera paludosa (Diptera, Ptychopteridae)

ABSTRACT. The microsporidium Janacekia adipophila n. sp., a parasite of Ptychoptera paludosa larvae in Sweden, is described based on light microscopic and ultrastructural characteristics. Merogonial stages and sporonts are diplokaryotic. Merozoites are formed by rosette-like division. Sporonts develop into sporogonial plasmodia with isolated nuclei. These plasmodia give rise to 8–16 sporoblasts by rosette-like budding. A sporophorous vesicle is initiated by the sporogonial plasmodium. Sporoblasts and spores are enclosed in individual sporophorous vesicles. Granular inclusions of the vesicles, visible using light microscopy, discriminate sporogonial stages from stages of the merogony. The monokaryotic, fresh spores are oval with blunt ends, measuring 4.2-6.3 × 9.1-11.2 μm. Macrospores are formed in small numbers. The spore wall has three subdivisions and the exospore is electron-dense. The polaroplast has two parts: closely arranged lamellae anteriorly, wider sac-like compartments posteriorly. The isofilar polar filament, 191–264 nm wide, has 12-13 coils, which are arranged in one layer in the posterior half of the spore. The electron-dense inclusions of the sporophorous vesicle are modified during sporogony, and vesicles with mature spores are traversed by 21–27 nm wide tubules, which connect the exospore with the envelope of the vesicle. The walls of the tubules, the envelope of the vesicles, and the surface layer of the exospore are all identical double-layered structures. The microsporidium is compared to microsporidia of Ptychopteridae and Tipulidae and to related microsporidia of the family Tuzetiidae.     

Development of the Mycetozoan Echinosteliopsis oligospora*

SYNOPSIS. The mycetozoan genus Echinosteliopsis, resembling the myxomycete Echinostelium in some of its features, is described. The single species, E. oligospora Reinhardt & Olive, forms small sporocarps which consist of a basal disk, stalk and a sporangium with only 1–8 spores. Spores form progressively, not simultaneously, by segmentation. The spores germinate to release non-flagellate amebae which, in liquid, assume a characteristic broad, fan shape. Each ameba has one or more nuclei. The nucleus is distinctive because of refractile, globular to elongate peripheral bodies which cytochemical tests indicate to be primarily RNA. At the time of nuclear division the characteristic RNA bodies disappear and, as observed with the phase microscope and in stained preparations, optically dense material accumulates in the middle area of the nucleus. Threads, either a spindle or actual chromatin, can be seen attached to the nuclear membrane. The threads separate to opposite poles as the nucleus elongates. During this division process the nuclear membrane apparently remains intact. Synchronous binucleate divisions, as well as a tripolar nuclear division, have been observed. Uninucleate and synchronous binucleate divisions may or may not be followed by cytokinesis. The absence of cell division after nuclear division leads to the production of cells with varying numbers of nuclei. Nuclear divisions in early sporangial stages and in spores have not been observed. The spores are uni- to multinucleate. In 8-spored sporangia and in most 4-spored sporangia there is a characteristic small “stalk spore” at the apex of the stalk. The stalk spore germinates slowly, if at all, but the larger spores germinate readily. No evidence of a sexual process has been found.     

Morphology,Molecular Phylogeny,and Ecology of Binucleata daphniae n. g., n. sp. (Fungi: Microsporidia), a Parasite of Daphnia magna Straus, 1820 (Crustacea: Branchiopoda)

ABSTRACT. We describe a new microsporidian species Binucleata daphniae, n. g., n. sp., that infects the integument cells lining the hemocoele cavity of the carapace and the postabdomen of the cladoceran Daphnia magna Straus. Infected cells filled with spores accumulate as large clusters in the carapace cavity and heavily infected hosts are detected by their opaque appearance. Despite the parasite's presence, infected Daphnia grow and molt, but have a reduced fecundity. During the parasite's life cycle, chain‐like meronts with isolated nuclei are formed, giving rise to binucleate presporonts, the most frequently observed, characteristic developmental stage. In sporogony, the nuclei of the presporont separate, divide, and eight spores enclosed in a thin‐walled sporophorous vesicle are formed. Spores are 4.9 × 2.5 μm in size (fresh) and have an anisofilar polar filament with eight coils. DNA sequence analysis places B. daphniae in a clade of microsporidians that parasitize crustaceans and mosquitoes and have assumed complex life cycles. Binucleata daphniae, however, has a simple and direct life cycle and can be transferred to naïve hosts and maintained as persistent infections in populations of its host D. magna. We propose that B. daphniae has simplified its life cycle by losing its secondary host, rendering it unique in this clade.     

Unclassified Protists of Arthropods: The Ultrastructure of Nephridiophaga periplanetae (Lutz & Splendore, 1903) N. Comb., and the Affinities of the Nephridiophagidae to Other Protists

Observations by electron microscopy were conducted on Coelosporidium periplanetae (Lutz & Splendore, 1903) Swarczewsky, 1914, an extracellular sporogenic protist in the lumen of the Malpighian tubules of Blatta orientalis Linn., 1758 and other domiciliary cockroaches. Results generally agreed with earlier studies by light microscopy but also allowed a more complete characterization of the species. Some outstanding features of the protist were: amoeboid multinucleate stages (plasmodia) capable of producing cytoplasmic projections for attachment to microvilli of tubules, endogenous formation of spores, differentiation of “generative” and “somatic” nuclei in plasmodia undergoing spore formation, polarized early sporoblasts (a nucleus on one half and a chondriome on the other), and biconcave, ovoid, non-polarized spores that are retained until maturation by the plasmalemma and residual cytoplasm of the original plasmodium. The new combination Nephridiophaga periplanetae is proposed based on this new, updated information. The family name Nephridiophagidae Sprague, 1970 is resurrected to include N. periplanetae and eleven other species of protists in the Malpighian tubules of arthropods, mostly insects in the orders Dictyoptera and Coleoptera. According to its characteristics, the family Nephridiophagidae cannot be included into any of the currently recognized phyla of protists. It is suggested that it should be temporarily treated as an incertae sedis group of Protista.     

Stempellia milleri sp. n. (Microsporida: Nosematidae) in the Mosquito Culex pipiens quinquefasciatus Say*

Stempellia milleri sp. n. was found in blood cells and the adipose tissue of field-collected larvae of Culex pipiens quinquefasciatus Say. Its development is different from other Stempellia species described in that it is dimorphic, producing two types of spores in adipose cells. Both were studied with the electron microscope. One spore is thin-walled and uninucleate; the other is thick-walled and binucleate. The latter spores are produced from sporonts that are somewhat similar to those of Nosema. Sporoblasts and spores of S. milleri were compared to those of Stempellia magna Kudo, and Stempellia lunata Hazard and Savage in both light and electron microscope preparations. S. milleri was transmitted experimentally to Culex pipiens pipiens, C. p. quinquefasciatus, C. salinarius, C. tarsalis, and C. territans. Transmission of S. magna to its host and other mosquito species was not possible. Although, generally low numbers of test larvae became infected with the pathogen, heavy infections were seen occasionally in individual specimens of its natural host, C. p. quinquefasciatus. Species of Aedes, Anopheles, Culiseta, Psorophora, and Uranotaenia exposed to spores of S. milleri were not susceptible to the disease.     

Microsporidium novacastriensis n. sp., a Microsporidian Parasite of the Grey Field Slug,Deroceras reticulatum1,2

A new species of microsporidium (phylum Microspora), Microsporidium novacastriensis n. sp., from the grey field slug, Deroceras reticulatum, is described on the basis of light and electron microscope studies. Meronts are spherical at first, then become irregular as nuclear number increases. Sporonts are tubular or ribbon-like and divide unevenly to produce sporoblasts and then spores of varying lengths. Sporogonial stages are enclosed in a vesicle by a subpersistent membrane of uncertain origin. Fresh spores measure 3.5 by 2.08 μm and are produced in clusters of 12 to 120. The parasite infects only the intestinal epithelium of the slug. The new species is compared to microsporidia of other gastropod molluscs and to other microsporidia of similar developmental pattern and morphology.     

Über die Struktur und Teilung der Kerne von Geotrichum candidum und Geotrichum magnusii

Summary The nuclei in germinating spores and growing hyphae ofGeotrichum magnusii andG. candidum have been examined during life and in fixed and stained preparations.The spores and the cells of the hyphae are multinucleate. The nuclei consist of a dense Feulgen-negative nucleolus surrounded by a less dense shell of Feulgen-positive particles. No membrane was seen at the margin of either living or fixed and stained nuclei. The mass of chromatin and the nucleolus divide at the same time by elongation followed by constriction. Chromosomes could not be detected in either resting or dividing nuclei.

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Mit 5 Textabbildungen     

Ultrastructural and Cytochemical Observations on Sporogenesis of Myxobolus sp. (Myxosporida: Myxobolidae) from the Common Shiner Notropis cornutus*

SYNOPSIS. The structure and cytochemistry of spores of Myxobolus sp. from plasmodia which occur in the gill filaments of the common shiner Notropis cornutus were studied by light microscopy and by scanning and transmission electron microscopy. The thin-walled valves of the pyriform spores are thickened in the lateral sutural and apical regions. Mucous material is associated predominantly with the posterior end of many spores. The plasmodium is surrounded by a syncytial wall bounded by 2 membranes. Pinocytotic channels are formed by the inner membrane and numerous dense vesicles are pinched off at the distal ends of the channels. Sporogenesis is initiated by the envelopment of one vegetative cell by another. The larger, enveloped cell divides to form a disporous pansporoblast, which contains 2 pairs of capsulogenic and valvogenic cells and 2 binucleate sporoplasm cells. Each capsular primordium and connecting external tubule gives rise to a polar capsule which houses a helically coiled polar tubule. The apical end of each polar capsule is plugged by a stopper. The valvogenic cells surround the capsulogenic and posteriorly situated sporoplasm cells to form the spore valves. Iodinophilic (glycogen) inclusions were not seen in spores stained with iodine or Best's carmine. A darkly stained band was observed around the posterior region of most spores stained with Best's carmine. In the electron microscope large aggregates of β glycogen particles were seen in the cytoplasm of sporoplasm cells in mature spores.     

Establishment of Endoreticulatus N. G. for Pleistophora fidelis (Hostounský & Weiser, 1975) (Microsporida: Pleistophoridae) Based on the Ultrastructure of a Microsporidium in the Colorado Potato Beetle,Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)1,2

A new genus, Endoreticulatus n. g., is described for the microsporidium Pleistophora fidelis (Hostounský & Weiser, 1975) based on light and electron microscopic studies of a microsporidium in the Colorado potato beetle, Leptinotarsa decemlineata (Say). This latter microsporidium is considered to be conspecific with P. fidelis because both isolates have been shown to be infectious for L. decemlineata where infection is limited to the epithelial cells of the midgut; both are haplokaryotic and develop as groups of sporoblasts and spores in subpersistent vacuoles in the host cell. In addition, meronts, sporonts, and spores of each isolate often occur simultaneously in a common cell, and by light microscopy they both appear similar. Ultrastructural studies of the isolate from L. decemlineata revealed that all developmental stages occur in parasitophorous vacuoles derived from cisternae of rough endoplasmic reticulum of the host cell cytoplasm. Based on the unique nature of the parasitophorous vacuole, a new genus, Endoreticulatus, is proposed for P. fidelis. The genus is compared with the other genera whose species undergo multisporous sporogony in sporophorous vesicles. In addition, the nature of the parasitophorous vacuole of Endoreticulatus fidelis (Hostounský & Weiser, 1975) n. comb. is compared with the parasitophorous vacuole known to encase various developmental stages of several other microsporidian species.     

Vesicular-arbuscular mycorrhizal spore populations in sugar maple (Acer saccharum marsh. L.) forests

 The numbers and types of spores of vesicular-arbuscular mycorrhizal fungi occurring in the top 15 cm of the soil in three maple forests in Eastern Canada were investigated using traditional wet-sieving/decanting methods. In the most acid site, at St. Hippolyte, Québec, where the soil had been amended with base cations, after 1 year there was no effect on the numbers of spores present. Vesicular-arbuscular mycorrhizal spores present at St. Hippolyte consisted of Glomus rubiforme, other Glomus spp. and Acaulospora spp. Although the sporocarpic species, G. aggregatum, G. macrocarpum and G. rubiforme occurred at St. Hippolyte, they were not found at the two less acid sites (Waterloo, Ontario and Lacolle, Québec) . Spores of Acaulospora spp. were found at all three sites, but were most abundant at St. Hippolyte. At St. Hippolyte the total number of spores was much higher than at the other two sites; at Waterloo numbers were an order of magnitude lower than at St. Hippolyte. It is suggested that G. rubiforme and Acaulospora species may be adapted to acid conditions. Seasonal patterns of spore abundance suggested that Acaulospora spp. may sporulate during the spring, whereas G. rubiforme may sporulate during the fall. Accepted: 6 September 1995     

Ultrastructure and Description of a New Species of Telomyxa (Microspora: Telomyxidae) from the Semiaquatic Beetle,Ora texana Champ. (Coleoptera: Helodidae)1

A new species of the uncommon microsporidian genus Telomyxa (Microspora: Telomyxidae) has been found parasitizing the larval fat body of the semiaquatic beetle, Ora texana. In this species, the sporogonic sequence results in the formation of sporocysts measuring 7.7 times 6.5 μm that contain two crested uninucleate spores (averaging 5.7 times 2.2 μm). The spores are essentially oblong/ovate, tapering toward the anterior end and remaining bound together after sporogony by a persistent accessory membrane or sporocyst. The two spores in the sporocyst are produced by an unusual morphogenetic sequence in which, after one mitosis, the binucleate sporont elongates, forming two lobes that fold toward one another and cleave along a central plane, forming two parallel sporoblasts. The general ultrastructural features of this process are described, and diagnostic characters of this new species of Telomyxa are presented.