A new lineage of crayfish-infecting Microsporidia: The Cambaraspora floridanus n. gen. n. sp. (Glugeida: Glugeidae) complex from Floridian freshwaters (USA).

Crayfish are a vital ecological asset in their native range but can be highly damaging as invasive species. Knowledge of their diseases, including high levels of research on Aphanomyces astaci (crayfish plague), show that disease plays a vital role during crayfish invasions. Microsporidian diseases in crayfish are less studied but are thought to have important links to crayfish health and invasion dynamics. In this study we provide a systematic description of a novel microsporidian parasite from the Floridian crayfish, Procambarus paeninsulanus, with additional genetic identification from related Microsporidia from Procambarus fallax, Cambarellus shufeldtii and Cambarellus blacki. This novel microsporidium from P. paeninsulanus is described in a new genus, Cambaraspora, and species, Cambaraspora floridanus, and represents a novel member of the Clade V Microsporidia within the Glugeidae. The parasite develops in the muscle tissue of P. paeninsulanus, within a sporophorous vesicle, and produces a spore with 19-21 turns of the polar filament measuring 6.136 ± 0.84 µm in length and 2.12 ± 0.23 µm in width. The muscle-infecting nature of the parasite suggests that it is horizontally transmitted. Genetic data for the 18S of the parasite from all hosts confirms its assignment to Clade V and reveal it to be a relative of multiple fish-infecting parasites. It shows closest genetic relationship to Glugea plecoglossi, but branches alongside multiple microsporidia from fish, crustaceans and eDNA isolates. The information presented here suggests that this novel parasite may have the potential to infect piscine hosts and is a likely mortality driver in the P. paeninsulanus population. Its potential as a control agent or wildlife disease invasion threat is explored, as well as the placement of this novel microsporidium within the Glugeidae.

Morphological and molecular studies of Vairimorpha necatrix BM, a new strain of the microsporidium V. necatrix (Microsporidia, Burenellidae) recorded in the silkworm, Bombyx mori.

Vairimorpha sp. BM (2012) is a recent isolate of the microsporidia from the silkworm in Shandong, China. The ultrastructure, tissue pathology and molecular characterization of this isolate is described in this study. This pathogenic fungus causes pebrine disease in silkworms which manifests as a systemic infection. Meanwhile, the silkworm eggs produced by the infected moths were examined using a microscope and PCR amplification. Neither spores nor the expected PCR band were observed, suggesting that no vertical transmission occurred in Bombyx mori. In addition, the ultrastructure of the isolate was studied by light microscopy and transmission electron microscopy. Two types of spores were observed: diplokaroytic spores with 13-17 coils of polar tubes and monokaryotic spores with less coils of polar tubes which could form octospores; however, no sporophorous vesicles were observed. Finally, phylogenetic analysis of the small subunit rRNA genes of Vairimorpha species showed that this isolate has a closer relationship to Vairimorpha necatrix than the other species studied. This result also is supported by phylogenetic analysis based on their actin genes, heat shock protein 70 (HSP70) and RNA polymerase II (RPB1). Based on the information gained during this study, we propose that this microsporidian species infecting B. mori should be given the name V. necatrix BM.

Hyperparasitism has wide-ranging implications for studies on the invertebrate phase of myxosporean (Myxozoa) life cycles.

All of the actinospore releasing oligochaetes collected in an environmental sample were found to be infected with the microsporidian Neoflabelliforma aurantiae n. gen. n. sp. Ultrastructural and phylogenetic studies on this microsporidian indicated similarities with Flabelliforma magnivora but not with the type species Flabelliforma montana, necessitating the formation of a new genus Neoflabelliforma and reassignment of F. magnivora as Neoflabelliforma magnivora n. comb. The development of N. aurantiae is described both parasitising the oligochaete worm and hyperparasitising the concurrent myxosporean infection. The effect of N. aurantiae on the myxosporeans was deleterious and progressive, eventually stopping all actinospore formation. Its discovery has the potential to impact on areas examining the phase of myxosporean life cycles in the invertebrate host, from transmission studies and epidemiology to re-evaluating the basic steps of intra-oligochaete development. Recent evidence has suggested that studies using invertebrate systems should consider possible adverse effects that co-infections can have on experimental outcomes. The discovery of N. aurantiae highlights the need for careful screening of experimental animals to help circumvent erroneous results.

Systenostrema alba Larsson 1988 (Microsporidia, Thelohaniidae) in the Dragonfly Aeshna viridis (Odonata, Aeshnidae) from South Siberia: morphology and molecular characterization.

An octospore microsporidium was found in the nymphs of Aeshna viridis, collected in intermittent streams near Novosibirsk, Siberia, Russia in 2003. Spores were uninucleate and measured 6.1+/-0.07 x 3.0+/-0.04 microm on fresh smears. The polar filament was anisofilar having 10-11 anterior coils (thicker filament diam.) and 10-11 posterior (thinner filament diam.) coils. Sporophorous vesicles were persistent and measured 12.3+/-0.23 x 11.9+/-0.20 microm. The infection was restricted to the adipose tissue and caused the formation of whitish "cysts" containing mature octospores. Based on ultrastructural similarity we consider this Siberian isolate to be Systenostrema alba, a species described from Aeshna grandis collected in Sweden (Larsson 1988). Maximum likelihood, neighbor joining, and maximum parsimony analyses of the small subunit rDNA all placed Systenostrema alba (Accession no. AY953292) as the sister taxon to a clade consisting of Thelohania solenopsae, Tubulinosema ratisbonensis, and Tubulinosema acridophagus.