Abstract: The oligotrich ciliates are important components of the marine microplankton. Many studies have been carried out on the taxonomy of these taxa in the past one and a half centuries. However, ambiguities concerning their identification have been accumulated due to lacking key morphological characters. Ten poorly known oligotrichs, Strombi-dium apolatum Wilbert & Song, 2005, Strombidium capitatum (Leegaard, 1995) Kahl, 1932, Strombidium guangdongense Liu, et al., 2016, Strombidium paracalkinsi (Lei, et al., 1999) Agatha, 2004, Strombidium parastylifer Song, et al., 2009, Strombidium suzukii Song, et al., 2009, Spirostrombidium cinctum (Kahl, 1932) Petz, et al., 1995, Paralle-lostrombidium jankowski (Song, et al., 2009) Song, et al., 2018, Parallelostrombidium kahli (Song, et al., 2009) Song, et al., 2018, Strombidinopsis minima (Gruber, 1884) Song & Bradbury, 1998 were investigated using live observation and protargol impregnation methods. Based on the present populations, much more information particularly with respect to their morphological features in vivo as well as original morphometric data were provided. Compared with previous population, some variable characters of these species were recorded.