First Record of Six Marine Ciliate Species of Genus Strombidium (Ciliophora: Spirotricha: Oligotrichia) from Korea with Ecological Notes

To supply the morphological and ecological information of oligotrich ciliates in Korea, water samples were seasonally collected in Gwangyang Bay and Jinhae Bay from August, 2010 to February, 2012 and processed by quantitative protargol staining method. As a result, six species belonging to the genus Strombidium Clapar$\grave{e}$de and Lachmann, 1859 are identified: Strombidium emergens Kahl, 1932; S. dalum Lynn et al., 1988; S. epidemum Lynn et al., 1988; S. tressum Lynn et al., 1988; S. bilobum Lynn and Gilron, 1993; S. pollostomum Lynn and Gilron, 1993. These six species were newly reported from Korean coastal waters. Strombidium emergens is a middle sized Strombidium ($20-50{\mu}m$ in length) and has open and deep oral groove to girdle portion. Strombidium dalum is a small sized Strombidium (${\geq}20{\mu}m$ in length), that has torch-like spiral anterior membranelles and an inverted triangles-shaped macronucleus on the posterior pole. The small sized S. epidemum has conspicuous trichites surrounding the girdle portion and ventral membranelles distinctly separated from anterior membranelles. The small sized S. tressum has torch-like spiral and extremely long trichites among the cilia of anterior membranelles. The middle sized S. bilobum has a bilobed macronucleus. Strombidium pollostomum is also a small sized Strombidium but its ventral membranelles are continuously connected with anterior membranelles. The five species except S. emergens occurred frequently over the wide range of water temperatures and salinities.