Morphological and molecular characterization of a new species, Cyclopispora nantong n. gen. n. sp. from the adipose tissue of Eucyclops speratus (Crustacea: Cyclopidae).

A new microsporidium, Cyclopispora nantong n. gen. n. sp., was described from the adipose tissue of Eucyclops speratus collected from a eutrophic water body of Nantong city, Jiangsu province, China. Infected copepods generally appeared opaque due to numerous spores accumulated in the adipose tissue. The earliest developmental stages observed were uninucleate meronts which resided in direct contact with the host cell cytoplasm. Mature spores were pyriform, monokaryotic, and measured 4.38 ± 0.20 (4.14-4.81) µm in length and 2.94 ± 0.09 (2.78-3.12) µm in width. The bipartite polaroplast consisted of the wide anterior lamellae and the tightly packed posterior lamellae. Isofilar polar filament coiled 13-16 turns and arranged in 3-4 rows. The 1306 bp SSU sequence obtained from E. speratus showed the highest similarity (85.9 %) to Hazardia milleri (AY09006) among the identified microsporidia. Phylogenetic analysis indicated that the present species clustered with an unidentified B. latissima lata-infecting species with high support values to form an independent branch which positioned the base of the Conglomerata-Gurleya-Agglomerata-Binucleata-Senoma-Pseudoberwaldia lineage. Based on the morphological characters and ultrastructural features, as well as SSU rDNA-inferred phylogenetic relationships, we propose the establishment of a novel genus (Cyclopispora n. gen.) and species (Cyclopispora nantong n. sp.) to contain this parasite.