Daphniaspora nanhuensis n. gen. n. sp. infecting the intestine of Moina micrura (Crustacea: Moinidae) in China.

We reported a new microsporidium, Daphniaspora nanhuensis n. gen. n. sp., from the intestine of Moina micrura collected from Lake Nanhu in Wuhan City, Hubei Province, China. Infected daphnids generally appeared to have hypertrophied and opaque intestines under light microscopy. Electron microscopy revealed all developmental stages residing in direct contact with the host cell cytoplasm. The earliest stages observed were uninucleate meronts with a round nucleus. Multinucleate sporogonial plasmodia developed into uninucleate sporoblasts by rosette-like budding. Mature spores were dumbbell-shaped, measuring 4.57 ± 0.40 (3.75-5.54) µm long and 1.79 ± 0.18 (1.40-2.23) wide. The bipartite polaroplast was composed of tightly packed anterior lamellae and wide posterior lamellae. Isofilar polar filaments coiled 5-6 turns and arranged in one row. The exospore consisted of three layers. BLASTn searches of obtained SSU rDNA sequence showed the highest similarity (78.52 %) with Liebermannia dichroplusae (GenBank accession number: EF016249). Phylogenetic analysis based on the obtained SSU rDNA sequence indicated that the present species represented an independent branch but formed a sister relationship with the genus Liebermannia. Based on the morphological characteristics, ultrastructural features, and molecular data, we propose the establishment of a novel genus (Daphniaspora n. gen.) and species (Daphniaspora nanhuensis n. sp.) to accommodate the present species.