Neoflabelliforma diaphanosoma n. sp. (Microsporidia) from hypoderm of diaphanosoma leuchtenbergianum (Crustacea: Sididae) in China.

A new microsporidian species was described from the hypoderm of Diaphanosoma leuchtenbergianum sampled from a eutrophic water body of Changshu city, Jiangsu province, China. Infected daphnia generally appeared opaque due to numerous spores accumulated in the host integument. The earliest developmental stages observed were uninucleate meronts which were in direct contact with the host cell cytoplasm. Multinucleate sporogonial plasmodia developed into uninucleate sporoblasts by plasmotomy. Mature spores were ovoid and monokaryotic, measuring 4.65 ± 0.21 (4.28-5.24) µm long and 2.49 ± 0.15 (2.12-2.82) µm wide. Isofilar polar filament coiled 8-11 turns and arranged in 2-3 rows. Bipartite polaroplast consisted of the tightly packed anterior lamellae and posterior tubules. The exospore was covered with tubular structures and was composed of two layers. Phylogenetic analysis based on the obtained SSU rDNA sequence indicated that the present species clustered with three Neoflabelliforma species (N. dubium, N. aurantiae, and N. leuchtenbergianum) and an unidentified microsporidium from soil with high support values to form an independent branch within canonical Microsporidia. Based on the morphological characters and ultrastructural features, as well as SSU rDNA-inferred phylogenetic relationships, a new species was erected and named as Neoflabelliforma diaphanosoma n. sp.