Strongylidium Sterki, 1878 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Hypotrichida: Suborder Stichotrichina: Family Strongylidiidae (ref. ID; 2014)
Class Polyhymenophora Jankowski, 1967: Subclass Spirotricha Butschli, 1889: Order Hypotrichida Stein, 1859: Suborder Stichotrichina Faure-Fremiet, 1961: Family Strongylidiidae Faure-Fremiet, 1961 (ref. ID; 4798)

[ref. ID; 2014]
Body approximately oval, dorso-ventrally flattened, posterior end may be bluntly pointed. 2 to 5 ventral and 2 marginal rows of cirri which spiral down the length of the body. Also 3 to 6 frontal cirri, the anterior most of which may be enlarged. Transverse cirri absent. Peristome short and less than a quarter of the body length. 2 or more macronuclei and an equal number of adjacent micronuclei. Several species have been described.
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)

Strongylidium californicum Kahl, 1932 (ref. ID; 4488) reported year? (ref. ID; 1308, 1618, 1621)
Description; 4-5 frontals; macronuclei about 30 in number; 4 micronuclei; contractile vacuole with short canals; fresh water among vegetation. (ref. ID; 1618)
Measurements; About 250 um long. (ref. ID; 1618)