Kerona Ehrenberg, 1835 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Hypotrichida: Suborder Stichotrichina: Family Keronidae (ref. ID; 2014)

[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 polyporum Ehrenberg, 1835 (ref. ID; 613, 4730, 7423) 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)
Description; Commensal on Hydra. (ref. ID; 1618)
Remarks; [Morphogenesis]: The N1 anlage for proter is not generated in the same row as for opisthe (i.e. in the second rightmost ventral row), but in the third ventral row from right and generates the three rightmost ventral rows four, five and six as in Onychodromus quadricornutus. Opisthe's anlagen for these rows develop as usual. Number of anlagen in frontal field reduced to three; anlagen 1 and 2 for proter are generated most likely de novo. The left marginal row (L1) is generated by neokinetal 5 development like in most parakahliellids; in this species all cirri of the old row are unused. Two dorsomarginal kineties and many dorsal kineties develop, the latter however, only from three anlagen each for proter and opisthe as in O. quadricornutus. (ref. ID; 7423)
Measurements; 120-200 um long. (ref. ID; 1618)