Taxonomic studies on Amphileptiscus shii nov. gen., nov. spec., a marine ciliate from China (Ciliophora, Pleurostomatida, Amphileptidae)

The morphology and infraciliature of a new pleurostomatid ciliate, Amphileptiscus shii nov. gen., nov. spec. found from the coastal water off Qingdao, China, are described. The new genus has the following combination of characters, which separates it from other pleurostomatids: dorsal margin at the anterior end is rolled up and curved to the left, forming a "spoon", and the ciliary rows on the right side form an anterior suture (the "spica") like that of Amphileptus. In vivo, the new species is about 60-120x15-25 mu m with a lanceolate outline and a laterally compressed body form; there are 22-27 somatic kineties on the right surface, 4-5 kineties on the left, two macronuclear segments, a single micronucleus, and a subterminal contractile vacuole; extrusomes are of two different shapes, rods scattered throughout the cytoplasm and long slightly curved bodies in a single bundle located at the anterior-most end. The systematic position of Amphileptiscus within the Amphileptidae in the newly revised order Pleurostomatida suggests that the morphological characteristics separating families should possibly be re-examined.