Fine structure and development of Pilosporella chapmani (Microspora: Thelohaniidae) in the mosquito, Aedes triseriatus (Say)

New information on the life cycle and fine structure of Pilosporella chapmani, a microsporidium of the mosquito Aedes triseriatus, is presented. Pilosporella chapmani is shown to have two sporulation sequences, one of them being involved in transovarial transmission. One sequence, involving meiosis and production of a moniliform sporogonial plasmodium, occurs in the larval fat body, resulting in eight uninucleate, spherical, and fully developed spores. The other occurs in oenocytes of adult mosquitoes and results in isolated, binucleate, elongate, and thin-walled spores. Also, for the first time, metabolic products are shown to be expelled into the surrounding host tissues through the wall of the sporocyst.     

Spore formation in the Actinoplanaceae (Actinomycetales)

Spore development in four genera, Actinoplanes, Dactylosporangium, Planomonospora, and Streptosporangium, was studied by transmission and scanning electron microscopy. Actinoplanes and Streptosporangium formed spores by fragmentation of a hypha within its expanded outer sheath, as do many other actinomycetes. Dactylosporangium and Planomonospora formed spores endogenously by development of wall material within the parent hypha. In this respect, they resembled the genera Actinobifida and Thermoactinomyces. The term sporangium has therefore been used to describe structures which are not homologous. It was suggested that the term should be confined to structures in which endogenous spore formation occurs.     

Sympatric population divergence within a highly pelagic seabird species complex (Hydrobates spp.)

Both physical and non‐physical barriers can restrict gene flow among seabird populations. Understanding the relative importance of non‐physical barriers, such as breeding phenology, is key to understanding seabird biodiversity. We investigated drivers of diversification in the Leach's storm‐petrel species complex (Hydrobates spp.) by examining population genetic structure across its range. Variation in the mitochondrial control region and six microsatellite loci was assayed in birds sampled from breeding colonies throughout the North Atlantic and North Pacific (H. leucorhoa leucorhoa), as well as from San Benito Islands (H. l. chapmani), and two seasonal populations in Guadalupe (summer breeding H. socorroensis and winter breeding H. cheimomnestes), Mexico. Weak but significant differentiation was found between populations of H. l. leucorhoa breeding in the Atlantic versus North Pacific, as well as between H. l. chapmani and H. l. leucorhoa, and between H. socorroensis and H. cheimomnestes within Guadalupe. In contrast, strong differentiation in both mitochondrial DNA and microsatellites was found between H. leucorhoa and both H. socorroensis and H. cheimomnestes. Phylogenetic reconstruction suggested the Guadalupe seasonal breeding populations are sister taxa, at least in their mitochondrial DNA. Non‐physical barriers to gene flow appear to be more important than physical barriers in driving divergence within the Leach's storm‐petrel species complex. In particular, allochronic speciation may have occurred between the seasonal populations within Guadalupe. Further work should include higher resolution sequencing to confirm results, and an increased sampling effort, particularly within the California area, to fully resolve the relationship between H. l. leucorhoa and H. l. chapmani.     

The cave population of Chaerilus Simon, 1877 from Palawan,Philippines, and description of a new species (Scorpiones: Chaerilidae)

The study of an important collection of scorpions, belonging to the genus Chaerilus, recently collected from a cave in the Palawan Island, Philippines, allows the clarification of the identity of this population, often misidentified with Chaerilus chapmani Vachon & Lourenço, 1985 known from caves in the Gunong Mulu National Park in Sarawak (Borneo). Chaerilus agnellivanniorum sp. n. is described from the Puerto Princesa Underground River Cave in Palawan Island based on 14 specimens, males, females, and juveniles. The new species is totally distinct morphologically from Chaerilus chapmani, a true troglobitic species. Chaerilus agnellivanniorum sp. n. may also be a true troglobitic element, but with a less marked degree of regression for several characters. Some comments on the ecology of the new species and on regional biogeography of Borneo and Palawan islands are also proposed.     

The spores of Pteris cretica complex (Pteridaceae-Pteridophyta) in America

Spore morphology in the Pteris cretica complex, including Pteris brasiliensis, P. ciliaris, P. cretica, P. denticulata var. denticulata, P. denticulata var. tristicula, P. ensiformis, P. multifida and P. mutilata was examined using light and scanning electron microscope. The spores are trilete, triangular to circular in shape, with an equatorial thickening (= cingulum). Equatorial diameter ranges from 29 to 69 μm, and polar diameter from 18 to 53 μm. Exospore is proximally verrucate and distally rugate, with the exception of Pteris ensiformis, which has cones on both polar faces. Perispore is generally less than 1 μm thick, apparently single-layered in section, and translucent under light microscope. Spheroids were frequently observed on the surfaces of both perispore and exospore. Hyaline spores lacking cingulum were found in all specimens. Pteris brasiliensis, P. cretica and P. denticulata exhibit pronounced polymorphism and, in addition to trilete spores these taxa also produce atypical spores such as tetralete, monolete and intermediate types.     

Fossil spores and pollen grains of cretaceous (Upper campanian) from Sakhalin, Russia

This paper shows fossil spores and pollen grains from Cretaceous (Upper Campanian) of Sakhalin, Russia, with scanning electron microscopy. A total of 520 palynomorph assemblages consisting of 25% spores of pteridophytes and bryophytes, 4.5% of ephedroid pollen grains, 6.5% of coniferous pollen grains, and 64% of angiospermous pollen grains were recovered in the present study. 5 genera of pteridophytes, 4 genera of gymnosperms, and 18 genera of angiosperms are described in the present study. The frequent and representative genera from the stratum areEphedripites, Liliacidites, Clavatipollenites, Tricolpites, Aquilapollenites, andAzonia. A new genus,Sciadopitipollenites, that is comparable with extantSciadopitys is proposed in the present study. Polycolpate pollen with the same exine sculpture ofClavatipollenites suggests a generic differentiation in the Chloranthaceae during the Cretaceous age. The diverse spores and pollen paleoflora shown in the present study suggests a wide diversification of angiosperms in the Upper Campanian at the eastern side of Laurasia (Aquilapollenites province).     

Influence of Dimilin on a microsporidian infection in the gypsy moth Lymantria dispar (L.) (Lepidoptera: Lymantriidae)

Bioassay studies were conducted to investigate the influence of Dimilin (diflubenzuron), a chitinsynthetase inhibitor used for insecticidal control of the gypsy moth, Lymantria dispar, on the development and viability of a microsporidian pathogen of L. dispar. Before or after an infection with a Nosema species, L. dispar larvae were fed Dimilin in sublethal dosages. Dimilin fed to L. dispar larvae at 0.65 ng/cm² diet surface resulted in a total larval mortality of 53%. Although the microsporidian infection alone did not cause high mortality rates (9%), mortality increased to 96% when L. dispar larvae were inoculated with both Dimilin and Nosema spores. When Dimilin was fed to the larvae 24 h before or 6 days after inoculation with the microsporidium, the number of mature spores produced was significantly reduced. When Dimilin was fed to the larvae 24 h after microsporidian inoculation, the number of spores produced was not significantly reduced. Spores that were produced in larvae after Dimilin had been ingested with the diet were less infectious than spores produced in control larvae; the experimental infection rate decreased from 94% when spores obtained from control larvae were used, to 48 or 10% when spores obtained from larvae fed Dimilin 24 h or 6 days after Nosema inoculation, respectively, were used. Mature microsporidian spores washed in Dimilin solution prior to oral inoculation, however, were as infectious as spores stored in liquid nitrogen. We have shown that Dimilin interferes with the establishment of the parasite in its host. In addition, when Nosema sp. succeeds in infecting the L. dispar host despite treatment with Dimilin, the microsporidium does not develop optimally and spore production is reduced.     

Airborne basidiospores in the atmosphere of Seville (South Spain)

Basidiomycetes produce large quantities of spores that are dispersed by the wind over long distances. Some species can release billions of spores in a day, many of which are important aeroallergens associated with asthma and allergic rhinitis. The results of a survey carried out in the city of Seville during two consecutive years, using a Hirst-type spore trap, showed that airborne basidiospores are present throughout the year, although there is a certain seasonal distribution, with the highest average concentration occurring in November (23,586 basidiospores). Eighteen different types of basidiospores were identified, with Coprinus and Ustilago being the most frequent, followed in descending order of abundance by Agaricus, Phylacteria, Boletaceae, Ganoderma, Cortinarius, Calvatia, Agrocybe, Bovista and Puccinia; the remaining spore types comprised less than 1% of the total basidiospore count.     

EXTERNAL SPORE MORPHOLOGY AND TAXONOMIC AFFINITIES OF PHYLLOGLOSSUM DRUMMONDII KUNZE (LYCOPODIACEAE)

The external spore morphology of Phylloglossum drummondii was studied with the scanning electron microscope and shown to share a number of features with spores in the subgenus Urostachys in Lycopodium. Within Urostachys the affinities of P. drummondii were less evident: the foramino-fossulate distal face, pyramidal proximal surface, and subcircular outline of its spores are similar to spores in the section Phlegmaria while the weakly foveolate proximal surface and raised laesurae are characteristic of spores in the section Selago.     

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.     

Spore morphology of Serpocaulon A.R.Sm. and related taxa from Brazil (Polypodiaceae)

The epiphytic fern genus Serpocaulon (Polypodiaceae) comprises 42 species nested within the neotropical clade of the family together with genera such as Campyloneurum, Grammitis, Microgramma, Niphidium, Pleopeltis, Pecluma, Polypodium and Terpsichore. Although Serpocaulon is a well-supported genus, its intra-specific relationships are still not completely resolved. The morphological dataset for Serpocaulon and related genera is therefore expanded here with information on spore morphology to provide additional information for phylogenetic consideration. Spores have been collected from herbarium vouchers and acetolysed for light and scanning electron microscopy. All members of the neotropical clade have monolete spores, except for Grammitis and Terpsichore, which have trilete spores. Both verrucate and papillate ornamentation types are recognised. The palynological analysis shows close similarity between spores of Serpocaulon, Campyloneurum, Pleopeltis and Polypodium and supports close phylogenetic relationships between these taxa. Species of the grammitid clade, although nested within the Polypodiaceae, have spore morphology that supports a separate position.     

On Chytridium braun,Diplochytridium N. G., and Canteria N. G. (Chytridiales)

Summary The operculate genus Chytridium Braun is emended and restricted to approximately 25 known species and several incompletely known members which lack an apophysis and develop much like species of Rhizophydium, insofar as the zoosporangium and absorbing or rhizoidal system are concerned, and form endobiotic or intramatrical resting spores. This interpretation corresponds fairly closely to Braun's diagnosis of the type species.A new genus, Diplochytridium, is established to segregate the former Chytridium species with an endobiotic or intramatrical apophysis or prosporangium and resting spores, which may develop sexually or asexually. Some of these species have a well-defined endo-exogenous alternation of growth and development in which the apophysis appears to function as a prosporangium. As interpreted here, Diplochytridium includes approximately 20 of the known species.Another new genus, Canteria, is created for a parasite of Mougeotia which Canter first described as a species of Phlyctidium but later found to develop endobiotic resting spores or zygospores by the fusion of conjugation tubes.     

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.     

Selection of Antonospora locustae (Protozoa: Microsporidae) with higher virulence against Locusta migratoria manilensis (Orthoptera:Acrididae)

Antonospora locustae is a microsporidian parasite of grasshopper insects that is used as a biological control agent. We report on laboratory selection of isolates from different regions with increased virulence. Bioassays were conducted against third instar nymphs of Locusta migratoria manilensis. AL2008L01 was originally imported from the USA in 1986, AL2008M01 was isolated from Melanoplus differentialis in USA and AL2008F01 was isolated from infected Fruhstorferiola tonkinensi collected in Guangdong, China. The results showed that all three isolates can infect the locust and that pathogenicity increased gradually with increased dose. The LD₅₀ values of the original isolates at the highest dose (5×10⁶ spores/nymph) were 19, 23 and 22 days and LD₅₀ values were 3.2×10⁵, 3.4×10⁶ and 0.7×10⁶ spores/g, respectively. After selecting for three generations, the virulence of all isolates increased significantly. LT_50s were reduced to 17, 20 and 21 days at the highest dose (5×10⁶ spores/nymph) and LD_50s were reduced to 1.4×10⁵, 2.5×10⁵ and 1.7×10⁵ spores/g.     

AUTOINHIBITION OF SPORE GERMINATION IN NOSTOC SPONGIAEFORME (CYANOPHYCEAE)1

Medium in which cultures of Nostoc spongiaeforme Ag. have sporulated contains one or more substances which inhbit the germination of spores (akinetes) of this organism. Germination of spores occurs rapidly in the absence of these substances, but is virtually completely suppressed in their presence.     

Intradiurnal periodicity of fungal spore concentrations (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) in Cracow, Poland

Aerobiological monitoring enables the definition of seasonal fungal spore concentrations and also intradiurnal time when the highest concentrations of spores could cause or increase allergy symptoms. These data are useful to estimate symptoms of disease, duration of infection and how advanced the illness is in people suffering from fungal allergens. The aim of the study was to compare the concentrations of fungal spores (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) during dry and rainy periods and to analyse their intradiurnal changes. Average daily spore concentrations in dry and rainy periods were compared, using z test, separately for each taxon, season and for a combined 3-year period. Intradiurnal periodicity of fungal spore concentrations was analysed on the basis of three complementary diagrams. These spore concentrations were presented using three curves for all, dry and rainy days in 1997–1999 (April–November). The spore percentage in particular hours was normalized in relation to the daily spore sum accepted as 100%. Two further diagrams enabled the more precise analysis of the highest concentrations in dry days. Daily Botrytis and Cladosporium spore concentrations did not show significant differences between dry and rainy periods. In the case of Didymella and Ganoderma spore concentrations, there were no significant differences between both weather types in the single years, although there was a significant difference when a 3-year period was considered. The differences between daily concentrations of Alternaria spores in dry and rainy periods occurred in 1997 and in a 3-year period. Intradiurnal periodicity of spore concentrations was different for ‘dry’ and ‘wet’ fungal spores. Dry spores are released from the spore-producing parts of the fungus under conditions of decreasing humidity and increasing airflow. Examples of dry spores are those from Alternaria, Cladosporium and Botrytis. Wet spores, such as those from many Ascomycetes (Didymella) and Basidiomycetes (Ganoderma), are released into the atmosphere by processes related to humidity conditions or rain. The highest concentrations of ‘dry’ spores were observed early in the afternoon, while highest values of ‘wet’ spore concentrations occurred in the predawn hours. Statistically non-significant differences between daily spore concentrations in dry and rainy periods of single seasons were found except for Alternaria. Statistically significant differences could occur when the studied period was longer than one season (Alternaria, Didymella, Ganoderma). The highest concentrations of Alternaria, Botrytis and Cladosporium spores were recorded at noon and early in the afternoon. Concentrations of Didymella and Ganoderma spores were highest in the predawn hours.     

Temperature-Dependent Spore Dimorphism in Burenella dimorpha (Microspora: Microsporida)

Burenella dimorpha, a microsporidian parasite of the tropical fire ant, Solenopsis geminata, produces two morphologically distinct types of spores. The binucleate free spores (spores not bound by a pansporoblast membrane) develop normally at temperatures at least as low as 20°C and as high as 32°C. The uninucleate octospores (spores bound in octets by a pansporoblast membrane), however, develop in a restricted range of temperature. Octospores constituted 35.9%± 2.6 of the spores in 25 pupae held at 28°C. Raising the temperature to 30°C reduced octospores to < 1% of the total spore population. Lowering the temperature to 25° or 22°C reduced the octospore population to 8.5%± 6.5 or 0.4 ± 0.5, respectively. Inhibition of octospore development was complete at 20°C. In contrast, the octospores of Vairimorpha necatrix and Vairimorpha plodiae are reported to be abundant at 16°C and 21°C, respectively. The critical event blocked in octospore development may be meiosis, as evidenced by an abundance of binucleate sporonts in the octospore sequence of development, and absence of more advanced sporogonic stages in hosts held at inhibitory temperatures. Free spore size is not affected by temperature although yield may be slightly reduced at elevated temperature.     

The effect of meteorological factors on the daily variation of airborne fungal spores in Granada (southern Spain)

A study was made of the link between climatic factors and the daily content of certain fungal spores in the atmosphere of the city of Granada in 1994. Sampling was carried out with a Burkard 7-day-recording spore trap. The spores analysed corresponded to the taxa Alternaria, Ustilago and Cladosporium, with two morphologically different spore types in the latter genus, cladosporioides and herbarum. These spores were selected both for their allergenic capacity and for the high level of their presence in the atmosphere, particularly during the spring and autumn. The spores of Cladosporium were the most abundant (93.82% of the total spores identified). The Spearman correlation coefficients between the spore concentrations studied and the meteorological parameters show different indices depending on the taxon being analysed. Alternaria and Cladosporium are significantly correlated with temperature and hours of sunlight, while Ustilago shows positive correlation indices with relative humidity and negative indices with wind speed. Received: 16 April 1998 / Revised: 27 September 1999 / Accepted: 27 October 1999     

Life Cycle of Culicospora magna (Kudo, 1920) (Microsporida: Culicosporidae) in Culex restuans Theobald with Special Reference to Sexuality1

The life cycle of Culicospora magna (Kudo, 1920) Weiser, 1977, consists of two major developmental sequences that alternate in host individuals of successive generations, each of the sequences starting with a sporoplasm and ending with spores. The first sequence occurs in larval, pupal, and adult stages of a parental generation of the host mosquito, Culex restuans Theobald; it begins with a sporoplasm from an ingested uninucleate spore and progresses through stages in gametogony, plasmogamy, nuclear association, merogony, karyogamy, and disporous sporulation with production of binucleate spores that discharge sporoplasms into the oocytes. The second sequence occurs in egg and larval stages of a filial generation of the same host species; it begins with the binucleate sporoplasm that entered the egg, includes stages in merogony, nuclear dissociation, and mictosporous sporulation, and ends with uninucleate spores. These spores are released into the environment following death of the host and are capable of infecting new parental generation host individuals. The life cycle is conceived as an alternation of generations related to haploidy and diploidy in the nuclei, the transition from haploidy to diploidy occurring with nuclear association and the transition from diploidy to haploidy occurring with nuclear dissociation.     

The occurrence and effect of a protozoan parasite, Ophryocystis elektroscirrha (Neogregarinida: Ophryocystidae) on overwintering monarch butterflies, Danaus plexippus (Lepidoptera: Danaidae) from two California winter sites

Abstract.

• 1 Monarch butterflies, Danaus plexippus, from two overwintering populations, were found to have Ophryocystis elektroscirrha spores on their scales at rates between 53% and 68%. The frequency of butterflies with O.elektroscirrha spores remained about the same between sites and throughout the winter.
• 2 The spores, recovered from all parts of the body of the butterfly, were most numerous on the abdomen, particularly near the posterior third.
• 3 Butterflies with spores survived as long as those without detectable spores at 10.1°C ±0.4 SE and 78.3% r.h. ±0.6SE. Insects with spores held at 19.4°C ±0.4SE and 44.9% r.h. ±1.5SE showed a significantly higher rate of moisture loss and survived a shorter period than monarch butterflies without detectable spores.