Redescription and Molecular Phylogeny of Zschokkella parasiluri Fujita, 1927

In order to confirm the validation of Zschokkella parasiluri Fujita, 1927, redescription and molecular phylogeny on Z.parasiluri collected from Jialing River, Chongqing, China.were conducted, Comparative analyses on Z.parasiluri and related species were conducted based on morphological characteristics, 18 SrDNA variation sites, genetic distances, sequence similarities, phylogenetic analysis.The results indicated that the spore shape of Z.parasiluri was oval with 711 striations paralleling to the suture ridge (“S”form) on the surface of shell valves.Its spore was 11.84±0.32 (11.3312.60) μm long, and 5.44±0.15 (5.095.78) μm wide, each spore had two equal spherical polar capsules 3.82±0.24 (3.454.22) μm in diameter, and positioned at both ends of the spore.The distance between the two polar capsule was 2.60±0.23 (2.232.87) μm and the polar filaments were obvious and coiled 56 turns.The results also indicated that the sequence similarity between the Chongqing population of Z.parasiluri (GenBank accession no.MH517584) and the Hubei population of Z.parasiluri (GenBank accession no.DQ377689) was 99%, and the genetic distance of them was 0.004.There were only 8 variable sites between the sequences of the two populations.There was no record of Z.parasiluri in this area, hence, Chongqing was a new distribution area of this species.Phylogenetically, Myxidiidae was composed of seawater branch and freshwater branch;Myxidiumand Zschokkellaclustered together with each other which showed the non-monophylogeny and close genetic relationships of two genara.