Family SPIROFILIDAE von Gelei, 1929

Syns.

Atractidae, Hypotrichidiidae, Kahliellidae

Ventral cirri inconspicuous and in quite numerous and/or helically spiraled rows; zone of adoral membranelles not highly prominent; various body shapes, with some forms tailed and others more elongate at the anterior end; lorica produced by some species; stomatogenesis parakinetal in primitive genera (e.g., Hypotrichidium and Kahliella).

[Nomenclatural note: although the generic name Spirofilum must, by the law of priority, fall as a junior synonym of the older Hypotrichidium, it is perfectly legitimate to maintain the familial name founded on it: thus Spirofilidae is correct, and Jankowski's (1975) recent "replacement" name of Hypotrichidiidae must be treated as a (junior) synonym.]

Atractos Vórósváry, 1950. Single species.
Hypotrichidium Ilowaisky, 1921 (syn. Spirofilum von Gelei, 1929 [non von Gelei, 1944] ). Few to several species.
Kahliella Corliss, 1960 (for Kahlia). Several species.
Plesiotricha Dragesco, 1970 (syn. Uroleptopsis p.p.). Single species.
Spiretella Borror, 1972 (for Spiretta; syns. Microspiretta, Spiratella [hom.] ). Single species.
Spirofilopsis Corliss, 1960 (for Spirofilum von Gelei, 1944 [non von Gelei, 1929] ). Single species.
Stichotricha Perty, 1949. Several species.
Urospinula Corliss, 1960 (for Urospina). Few species.
Incertae sedis:
Kahliela Tucolesco, 1962. Single species. [Though poorly described, this was erected as a separate genus, despite the fact that the name gives the appearance of being merely a misspelling of Kahliella.]