Ultrastructure of Minchinia Sp. Spores from Shipworms (Teredo Spp.) in the Western North Atlantic, with a Discussion of Taxonomy of the Haplosporidiidae

Electron microscopy of haplosporidan spores from Teredo navalis and T. furcifera revealed 4 distinct membrane-bound extensions, 1 apical extension opposite the opercular hinge, 1 terminal and 2 opposing lateral extensions. These extensions were not continuous with the spore wall, but contained microtubule-like structures and degrading epispore cytoplasm. No other known species in the family Haplosporidiidae is characterized by spores possessing four epispore extensions. There are currently two genera in this family, Minchinia and Haplosporidium. The genus Minchinia includes spores such as those of M. chitonis which bear two epispore cytoplasm extensions. Spores of the genus Haplosporidium have been characterized by spore wall derived filaments. A 3rd group of haplosporidan species with spores ornamented by wrappings have traditionally also been assigned to the genus Haplosporidium. Based on the presence of epispore cytoplasm extensions rather than spore wall filaments, the haplosporidan of Teredo spp. can be placed in the genus Minchinia.     

Light and ultrastructural data on Henneguya testicularis n. sp. (Myxozoa,Myxobolidae), a parasite from the testis of the Amazonian fish Moenkhausia oligolepis

Light and electron microscopical data on a myxosporidian found in the testis of Moenkhausia oligolepis Gunther (Teleostei, Characidae, Tetragonopterinae) from the lower Amazon River near Belém, Brazil, are described. Based on spore morphology, we conclude that this species belongs to the family Myxobolidae and genus Henneguya. Mature spores (total length 27.5 (27.0–28.5) µm) were observed at the periphery of the testis. The ellipsoidal spore body consists of two unequal shell valves adhering together along the suture lines. The spore body is ellipsoidal, 14.0 µm long and 6.5 µm wide. Each valve tapers to a single caudal projection, forming a 13.5 µm long tail (13.0–14.5 µm). The spore is surrounded by a homogenous dense sheath. The polar capsules, measuring 9.0 × 2.0 µm, contain 12–13 coils of the polar filaments. Morphological differences between this material and other species of the genus Henneguya indicated the erection of a new species, which was named H. testicularis. The taxonomic affinities of this parasite are discussed.     

Ultrastructural description of the spore maturation stages of the clam parasite Minchinia tapetis (Vilela, 1951) (Haplosporida: Haplosporidiidae)

The fine structure of maturing spores of a haplosporidian parasite found in the gill, mantle and foot tissues of Ruditapes decussatus L. (Mollusca, Bivalvia), a species of commercial importance in Portugal, is described. When observed free in suspension, immature spores exhibit one or two epispore cytoplasmic extensions (ECE) which constitute a projection of a portion of the exosporoplasm, sometimes without ultrastructural organisation, surrounded by the plasmalemma. Free spores observed by light microscopy (LM) after 3-5 days of incubation in filtered sea-water exhibit no ECE attached to the spore wall. The mature spore is ovoid to ellipsoid, operculate, uninucleate and measures c. 4.8 microm long and c. 3.9 microm wide. The spore shape and size and the identity of the host living in the same geographical region suggest that this species is the same as previously described using LM observations as Haplosporidium tapetis Vilela, 1951 and later transferred to Minchinia Labbé, 1896.     

Spore ornamentation of Haplosporidium nelsoni and Haplosporidium costale (Haplosporidia), and incongruence of molecular phylogeny and spore ornamentation in the Haplosporidia

Spore ornamentation of Haplosporidium nelsoni and Haplosporidium costale was determined by scanning electron microscopy. For H. nelsoni, the spore surface was covered with individual ribbons that were tightly bound together and occurred as a single sheet. In some spores, this layer was overlaid with a network of branching fibers, about 0.05 microm in diameter, which often was dislodged from the spore at the aboral pole. For H. costale, ornamentation consisted of a sparse network of branching fibers on the spore surface. Molecular phylogenetic analysis of the phylum Haplosporidia revealed that Urosporidium, Bonamia, and Minchinia were monophyletic but that Haplosporidium was paraphyletic. All species of Minchinia have ornamentation composed of epispore cytoplasm, supporting the monophyly of this genus. The presence of spores with a hinged operculum and spore wall-derived ornamentation in Bonamia perspora confounds the distinction between Bonamia and Haplosporidium. Species with ornamentation composed of outer spore wall material and attached to the spore wall do not form a monophyletic group in the molecular phylogenetic analysis. These results suggest that the widely accepted practice of assigning all species with spore wall-derived ornamentation to Haplospordium cannot be supported and that additional genera are needed in which to place some species presently assigned to Haplosporidium.     

Sporulation of Minchinia sp. (Haplosporida, Haplosporidiidae) in the Pacific Oyster Crassostrea gigas (Thunberg) from the Republic of Korea

SYNOPSIS. A haplosporidan parasite belonging to the genus Minchinia was found in 4 of 1,438 oysters, Crassostrea gigas , collected from the Republic of Korea. Multinucleated vegetative stages were present in the infected oysters. Spores found in one of these oysters were acid-fast and had operculate characteristics of the genus Minchinia .     

Two species of myxozoan parasites (Myxosporea: Bivalvulida), including a new genus,fromPatagonotothen sima (Richardson, 1845) (Pisces: Teleostei) in the southwest Atlantic

A new genus and species of myxozoan parasite,Renispora simae, is described from the gall-bladder of the nototheniid fishPatagonotothen sima (Richardson). Four of 12 fish caught in Stanley harbour in the Falkland Islands in May, 1993 were infected. The new genus is placed in the family Alatosporidae and differs from other genera in this family by the shape of the spore body and the shape and site of adhesion of the membranous extensions to the spore valves. To accommodate the new genus, we propose an amendment to the definition of the family Alatosporidae to include forms with reniform spores.Myxidium baueri Kovaleva & Gaevskaya, 1982 is reported fromP. sima for the first time. It was found in the gall-bladder of one of the same 12 fish caught in Stanley harbour.     

Pleistophora finisterrensis n. sp., a microsporidian parasite of blue whiting Micromesistius poutassou

Pleistophora finisterrensis n. sp. is a microsporidian parasite of the hypoaxial musculature of the blue whiting Micromesistius poutassou (Risso). Foci of infection are between 3 and 6 mm in length and have no evident effects on adjacent muscle fibres. We found only a single type of spore (uninucleate, with mean dimensions of 4×2 µm in fresh preparations), contained within sporophorous vesicles (mean diameter 19 µm in fresh preparations; 150–250 spores per vesicle). All of the development stages of this microsporidian are monokaryotic. The meronts are initially uninucleate and bounded by a plasmalemma. Towards the end of merogony, meronts are multinucleate plasmodia with a well-defined surface coat. Sporogony is polysporous, with multinucleate sporonts, which likewise have a well-defined surface coat (about 130 nm thick), dividing by plasmotomy to give rise to uninucleate sporoblasts. The polar tube is isofilar and consists of 8–9 turns in the posterior half of spore. The polaroplast is made up of an anterior lamellar part and a posterior vesicular part.     

Minchinia teredinis N. Sp. (Balanosporida, Haplosporidiidae), a Parasite of Teredinid Shipworms

ABSTRACT. A new species of ascetosporan parasitizing tissues of woodboring mollusks of the genus Teredo , including T. navalis Linnaeus, T. furcifera von Martens, and T. bartschi Clapp, is described from light and transmission electron microscopical observations. The new species is assigned the name Minchinia teredinis sp. n. (Phylum Ascetospora, Class Stellatosporea, Order Balanosporida, Family Haplosporidiidae). Plasmodia, sporonts, sporocysts, and mature spores are found in all host tissues, but primarily in the gill. Spores are obovate, operculate, and characterized by four projections from the epispore membrane. The species is found from Long Island Sound to Virginia on the east coast of the United States. The parasite causes extensive damage to host tissues and is correlated with reductions in host populations.     

Isospora ptyodactyli n. sp. (Apicomplexa: Eimeriidae), a new coccidian parasite of the fan-footed gecko Ptyodactylus puiseuxi Boutan, 1893 (Reptilia: Gekkonidae) from Jordan

Faecal samples from 17 fan-footed geckoes Ptyodactylus puiseuxi Boutan were examined for coccidian parasites. Five geckoes (29%) were found to be passing oöcysts of the genus Isospora Schneider. Comparison with other members of the genus Isospora indicates that the coccidian found represents a new species. Sporulated oöcysts of I. ptyodactyli n. sp. are spherical or subspherical, 22.1 (19.0–24.0) × 21.2 (18.0–23.0) µm, with a shape-index (length/width) of 1.04; and a smooth and bilayered oöcyst wall, 1.0–1.5 µm thick. A micropyle, oöcyst residuum and polar granule are absent. The sporocysts are ellipsoidal, 12.2 (11.0–14.0) × 8.0 (7.5–9.0) µm, with a shape index of 1.5 (1.4–1.9). Stieda and substieda bodies are present, the Stieda body being knob-like and the substieda body spherical to subspherical. A sporocyst residuum is present and composed of numerous granules of different size scattered among the sporozoites. The sporozoites are vermiform, with a slightly granulated surface appearance, and are arranged head to tail within the sporocyst. Most oöcysts have still to sporulate when excreted; sporulation was completed within 12 h at 25 °C. Endogenous development occurs inside the nuclei of enterocytes in the small intestine.     

Ultrastructure of the spore in four Japanese species of Ptychomitrium Fürnr. (Musci)

The ultrastructure of the mature spore in four Japanese species of the acrocarpous moss genus Ptychomitrium is presented. In all species the spores have a similar pattern: there is no recognisable aperture nor sporoderm polarity, exine and perine are poorly developed, cytoplasm only occasionally shows polarity, and plastids have a well developed inner membrane system. The presence of frequent intine protrusions is a remarkable feature of this genus. A multilaminar structure of the exine, already observed in Grimmia, occurs also in these species although here it is less pronounced. The significance of these features is discussed within these species, as well as in comparison to other taxa, especially the genus Grimmia.     

First finding of deepwater <Emphasis Type="Italic">profunda</Emphasis> morph of quagga mussel <Emphasis Type="Italic">Dreissena bugensis</Emphasis> in the European part of its range

The deepwater profunda morph of quagga mussel Dreissena bugensis was found for the first time in the European part of its range. The mussels of this morph were found in the Cheboksary Reservoir situated in the midstream of the Volga River (Russian Federation). Traditional and geometric morphometrics confirm the similarity of studied specimens to profunda mussel described from the Great Lakes of North America. In the Cheboksary Reservoir the deepwater mussels live at depth of 26.5 m on sandy-pebbled substrate at conditions of high water velocity (>0.5 m/s), i. e. in the conditions unusual for American profunda. This fact reflects evident ecological plasticity of this morph. Discovery of the deepwater morph of quagga mussel in the European part of its range indicates that possibility of realization of the deepwater phenotype is inherent to this species. It is suggested that quagga mussel may possess two alternative developmental pathways that could be realized in appropriate conditions. Presumably, certain depth and/or water pressure may serve as signaling factors for activating the “deepwater” developmental pathway. The presence of deepwater and shallow-water morphs is very important adaptive feature for sedentary organisms such as dreissenids that are unable to select habitat actively since this feature allows for successful colonization of both deep and shallow water habitats.     

Spore Morphology of Pteridophytes from China Ⅵ .Pteridaceae

The spore morphology of 30 species 4 variety of 2 genera of Pteridaceae from China was investigated under scanning electron microscope (SEM) . Among them, 29 species 4 variety belong to the genus Pteris . The spores of Pteris are trilete , radiosymmetrical , subtriangular in polar view and hemispherical or subhemispherical in equatorial view . The polar axes are 26 - 54μm long , and equatorial axes are 34 - 97μm long . The perispore is thin and the surface ornamentation is formed by the exospore . The types of ornamentation are tuberculiform-rugulate , verruciform-rugulate or lophate , the spore of most species with the equatoial flange, some species with proximal ridge and distal ridge . The spore morphology of Pteris is stable, and the difference between species is distinct , but the features of spore and sporophyte are not related. The spore of Histiopteris is monolete and bilaterally symmetrical, elliptical in polar view and kidney-shaped in equatorial view . The polar axes are 22 - 23μm long , and equatorial axes are 29 - 36 μm long . The perispore is thin and the surface ornamentation is formed by the exospore . The surface is rugulate . The spore morphology of Histiopteris and Pteris is very differential , put genus Histiopteris in family Pteridaceae is not suitable, according to the feature of spore morphology .     

中国蕨类植物孢子形态的研究 Ⅵ . 凤尾蕨科

利用扫描电镜对国产凤尾蕨科( Pteridaceae ) 2 属30 种4 变种植物孢子进行了观察。其中凤尾蕨属( Pteris) 29 种4 变种, 孢子三裂缝, 辐射对称; 极面观为钝三角形, 赤道面观为半圆形或超半圆形; 孢子极轴长26～54μm, 赤道轴长34～97μm; 外壁厚, 形成孢子表面纹饰的轮廓; 周壁薄, 紧贴于外壁上; 多数种类孢子外壁具沿赤道加厚的赤道环, 孢子表面呈瘤块状、疣块状, 或隆起的脊连成网状或拟网状等纹饰, 有的种类具近极脊和远极脊。凤尾蕨属植物孢子的形态稳定, 种间差异明显, 但孢子形态特征与孢子体的形态特征是不相关的。栗蕨属( Histiopteris) 植物孢子为单裂缝, 两侧对称, 极面观椭圆形, 赤道面观豆形; 孢子极轴长22～23μm, 赤道轴长29～36μm; 周壁很薄, 由外壁形成孢子纹饰的轮廓; 表面呈粗的块状纹饰。从孢子形态上看, 栗蕨属与凤尾蕨属有很大差异, 将其放在一个科中不合适。     

Description of a new species of myxobolid parasite,Henneguya pindaibensis n. sp. (Cnidaria: Myxosporea), infecting the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) from Brazil

Myxozoans are microscopic cnidarians that mainly parasitize fishes. The present study aimed to describe a new myxozoan parasite from the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) by morphological and molecular analysis. The fish was collected in 2019 at the Pindaíba River, municipality of Cocalinho, Mato Grosso State, Brazil. Whitish and circular plasmodia were found in the primary gill filaments, occupying an intralamellar position, with an average of 0.5 mm in diameter. Henneguya Thélohan, 1892 myxospores found inside the plasmodia were elongated and ellipsoidal, consisting of two long and elliptical shell valves with two long, tapering caudal appendages. Morphometric measurements revealed a total spore length of 36.1 ± 2.0 μm; spore body length of 12.8 ± 0.5 μm; spore width of 4.9 ± 0.3 μm; tail length of 23.3 ± 1.6 μm; capsule length of 7.2 ± 0.4 μm; capsule width of 1.5 ± 0.2 μm; and 10 coils in the polar filament. Phylogenetic analysis showed that the isolates from this study were grouped into the main-clade of freshwater fishes, within a group of species parasitizing fishes from Brazil. Intergenotypic difference ranged from 23%–25.9% compared with other Brazilian myxozoan isolates. Using molecular and morphological characterization, this parasite was identified as a new species of the genus Henneguya.     

Epiphytism and terrestrialization in tropicalHuperzia (Lycopodiaceae)

A gap in the exospore and the presence of a mesospore is found to be a normal part of development in the ten species ofSelaginella we have studied. The early spore wall consists of an exospore and a mesospore forming successively on the plasma membrane of the megaspore protoplast when it is 10–15 µm in diameter. Enlargement of the exospore and mesospore creates a central space, the lumen of the megaspore, around the megaspore protoplast. After that there is a vast enlargement of the exospore and a relatively small enlargement of the mesospore. The exospore splits close to its contact with the mesospore forming a gap over equatorial and distal regions. The gap becomes greatly expanded and becomes filled with lipids, PAS-positive carbohydrates, proteins and is crossed by wicks. Experiments with solutions of different osmolality on fresh megaspores show that the exospore and mesospore are not osmotic barriers. The mesospore appears not to be resistant to acetolysis at the many stages tested but exospore is resistant. Thus the mesospore size and shape is retained by the inner exospore that enveloped the mesospore. At maturation the mesospore undergoes lysis and absorption. At the beginning of germination stages an endospore forms at the inner part of the exospore. This inner part of the exospore, that adhered to and enveloped the mesospore, becomes pressed near to the bulk of the exospore. Until pregermination stages the megaspore protoplast is small (10–20 µm in diameter).     

Ultrastructure of Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Myxosporea), a parasite of the Amazonian freshwater fish, Sphoeroides testudineus (Teleostei, Tetrodontidae)

Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Ortholineidae), found in the lumen of the intestine of the freshwater fish Sphoeroides testudineus, is described. The fish were collected from the Amazon River near the city of Algodoal, State of the Pará, Brazil. Numerous irregular plasmodia containing different stages of sporogony, including spores, were observed. The plasmodia were lying free in the lumen or had slender pseudopodia-like cytoplasmic processes in contact with intestinal epithelial cells with microvilli projections. Spores, which are equilaterally triangular in valvar view with rounded pointed ends and ellipsoidal in transverse section, are 8.5 μm long, 7.6 μm wide, and 3.8 μm thick. The anterior end of the spores contains two equal drop-shaped polar capsules measuring 2.6 μm in length, each having an isofilar polar filament with 5–6 turns. The characteristics of the spore shape, the spore wall structure and its ridge organization, the plasmodial characteristics and the identity of the host suggest that the parasite is a new genus and species, which is herein designated T. amazonica.     

A Study on the Spore Morphology of Bryum Hedw. in China

Spore morphology of thirteen species of the genus Bryum Hedw. were observed by LM and SEM. The results show that the ornamentation of spore exine could be divided into three types: Type I , blunt at the top of baculate processes, to which four species belong: Bryum argenteum, B. lonchocaulon , B. uliginosum and B. arcticum. Type Ⅱ, sharp or with small processes at the top of baculate processes, represented by seven species: B. pallescens, B. caespiticium, B. pallens, B. pseudotriquetrum, B. paradoxum, B. alpinum and B. thomsoii. Type Ⅲ, expanded into hemispherical-shaped at the top of baculate processes, represented by two species: B.coronatum and B.sauteri. The Bryum species may also be divided into three groups according to the variation of spore diameter. Group I , with spore diameter under 10 μm, including one species, B. uliginosum. Group Ⅱ, with spore diameter 11～20 μm, including seven species: B. argenteum, B. alpinum, B. coronatum, B. pallens, B.paradoxum, B.sauteri, B.thomsonii. Group Ⅲ, spore diameter 21～30 μm, with five species: B. pallescens, B. caespiticium, B. pseudotriquetrum, B. lonchocaulon, B. arcticum. There are resemblances of spore morphology and exine ornamentation among the thirteen species. In the view of palynology, the genus Bryum is a natural taxon which is more advanced than the genus Pohlia Hedw. But spores of thirteen species are different at some characters such as diameter, shape ofproximal leptoma, etc., which indicates the genetic differentiation in the genus Bryum.     

Replacement of the preoccupied name Davisia Laird 1953 and description of a new myxozoan species (Myxosporea: Sinuolineidae) from Sebastiscus marmoratus (Cuvier, 1829) in the East China Sea

The myxozoan genus Davisia Laird 1953 is preoccupied by Davisia Del Guercio 1909 (Insecta: Hemiptera). Here, Myxodavisia nomen novum is proposed to replace the preoccupied name, and a new species is described. Myxodavisia sebastisca n. sp. was found in the urinary bladder of Sebastiscus marmoratus, collected from coastal waters off Xiamen in the East China Sea. The parasite is characterized by a disporous trophozoite; spherical to subspherical spore, 13.1 +/- 0.3 (12.7-13.6) by 12.3 +/- 0.9 (10.9-13.5) microm in size; curved sutural line; 2 shell valves each with a long lateral appendage 119.4-335.2 microm in length; and 2 spherical or subspherical polar capsules, equal in size, 4.6 +/- 0.6 (3.2-4.6) microm in diameter. Traditionally, Myxodavisia is distinguished from Ceratomyxa, Sinuolinea, and Sphaerospora spp. by having spores that possess a distinct central chamber and lateral appendages. A review of the literature reveals that the presence or absence of a clear septum between these spore components is open to interpretation. Indeed, in immature spores of M. sebastisca n. sp., there was an indication of a demarcated appendage, but in some mature spores, no clear separation was apparent. Our findings suggest that future revision of this genus is warranted, particularly once DNA sequence data become available.     

Pollen and anther development in Nelumbo (Nelumbonaceae)

The Nelumbonaceae are a small family of aquatic angiosperms comprising Nelumbo nucifera and Nelumbo lutea. Historically, the genus has been considered to be closely related to Nymphaeales, however new systematic work has allied Nelumbo with lower eudicots, particularly Platanus. In recent years, studies of pollen development have contributed greatly to the understanding of phylogenetic relationships, but little has been known about these events in Nelumbo. In this paper, pollen and anther development are morphologically described for the first time in N. lutea. A comprehensive ontogenetic sequence is documented, including the sporogenous tissue, microspore mother cell, tetrad, free spore, and mature pollen grain stages. The deposition of a microspore mother cell coat and callose wall, the co-occurrence of both tetrahedral and tetragonal tetrads, the formation of a primexine in tetrads, and primexine persistence into the late free spore stage are shown. The majority of exine development occurs during the free spore stage with the deposition of a tectate-columellate ectexine, a lamellate endexine, and an unusual granular layer below and intermixed with the endexine lamellae. A two-layered intine forms rapidly during the earliest mature pollen stage. Major events of anther development documented include the degradation of a secretory-type tapetum during the free spore stage and the rapid formation of U-shaped endothecial thickenings in the mature pollen grain stage. The majority of mature pollen grains are tricolpate, however less common monosulcate and diaperturate grains also develop. Co-occurring aperture types in Nelumbo have been suggested to be an important transition in angiosperm aperture number. However, aperture variability in Nelumbo may be correlated with the lateness of aperture ontogeny in the genus, which occurs in the early free spore stage. This character, as well as other details of pollen and anther ontogeny in Nelumbo, are compared to those of Nymphaeales and Platanus in an effort to provide additional insight into systematic and phylogenetic relationships. Although Nelumbo is similar to both groups in several characters, the ontogenetic sequence of the genus is different in many ways.