Morphological and molecular characterization of Aspidisca hongkongensis spec. nov. (Ciliophora, Euplotida) from the South China Sea.

The morphology and infraciliature of a new ciliate, Aspidisca hongkongensis spec. nov., a large marine form isolated from the coastal waters near Hong Kong, were investigated. It differs from the congeners by the combination of cell size (about 90 x 60 microm in vivo), 9-11 conspicuous dorsal ridges, one fine and seven strong frontoventral cirri, six membranelles in anterior portion of adoral zone, and 17-23 membranelles in posterior portion of adoral zone. The comparison with similar congeners clearly supports the distinction of this new species based on morphological and small subunit (SSU) rRNA gene sequence studies. The SSU rRNA gene sequence similarity within the genus is about 75.3-92.1% which indicates that this is a distinct form. Phylogenetic trees based on SSU rRNA gene information show that A. hongkongensis groups with A. leptaspis.