[ref. ID; 2014]
Kidney-bean shaped, dorso-ventrally flattened body, concave on left side, slightly pointed posteriorly. There are 2 marginal rows of cirri joining posteriorly. Distinct frontal cirri absent but there are 5 transverse cirri. 6 oblique, curving, subparallel rows of ventral cirri in the center of the body. AZM extends halfway down body length. Macronucleus in two parts. Ectocommensal on Hydra, on which it creeps rapidly, feeding on algae and ectodermal cells.
The nomenclatural difficulties of the genus are reviewed by Jankowski (1979) who concludes that the name should be Alastor Perty, 1852
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)

• Kerona pediculus (O. F. Muller, 1773) nov. comb. (ref. ID; 4730) or (O. F. Muller, 1773) Blochmann, 1886 (ref. ID; 4609) reported author and year? (ref. ID; 1629)
  Syn; Cyclidium pediculus O. F. Muller, 1773 (ref. ID; 4609, 4730); Kerona polyporum (Ehrenberg, 1835) Ehrenberg, 1838 (ref. ID; 4609)
• Kerona polyporum Ehrenberg, 1835 (ref. ID; 613, 4730) reported year? (ref. ID; 1335, 1618, 1621, 5462) reported author and year? (ref. ID; 191)
  See; Kerona pediculus (ref. ID; 4609, 4730)
  Syn; Alaster polyporum Perty, 1852 (ref. ID; 613); Cyclidium pediculus Muller, 1786 (ref. ID; 613)
• Kerona pustulata O. F. Muller, 1786
  See; Stylonychia pustulata (ref. ID; 4609)