Stranger in a strange land: An aquatic microsporidium Globulispora mitoportans in a terrestrial host, Amata phegea

A microsporidium was found in a single larva of the nine-spotted moth Amata phegea (Lepidoptera: Erebidae) in Central Bulgaria. Multiple mature spores, occupying inner tissues of the host, suggest infection rather than environmental contamination. This specimen was primarily processed for light microscopy and for sequencing of the small subunit ribosomal (SSU) region of rDNA. There were multiple ovoid spores, measuring 2.9 × 1.8 μm. The rDNA sequence (GenBank accession number PP003326) showed 99.3% similarity and a genetic distance of 0.006 to Globulispora mitoporans (#KT762153). This microsporidium, belonging to the Enterospora-like clade in the order of Enterocytozoonidae, is a pathogen of the water flea Daphnia pulex (Branchiopoda: Daphniidae). The same level of genetic divergence is observed in different geographical isolates of another species from the same clade - Enterocytospora artemiae. In the absence of tissue samples fixed for transmission electron microscopy, it was still possible to use remnants of infected host tissue from the Giemsa-stained slides for this procedure. The spores possessed a large single nucleus located in the center of the cell, a single layer of polar tube coils, a globose polaroplast, and an undulating layer of the spore wall. The ultrastructural composition of the spore also corresponded to that of Globulispora. The finding adds to our knowledge of ability of particular microsporidian parasites to penetrate hosts from diverse taxa and habitats.