Molecular phylogeny and Ultrastructure of a new population of Urostyla grandis (Ciliophora, Hypotrichida) from Harbin, China

A new population of Urostyla grandis, collected from a freshwater pond of northeastern China was investigated by living observation, silver impregnation, and molecular phylogeny based on small subunit ribosomal rRNA (SSU rRNA). Besides, its ultrastructural characteristics were investigated carefully by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Complementary descriptions of some inner ultrastructures were provided and some new organelles were also found. Especially, the oral inner microtubule system was illustrated by SEM and TEM for the first time and a new type extrusome was reported. These results may supply complement taxonomic data and ingestion mechanism on ciliates in genus Urostyla.