Suborder (2) Ophryoglenina Canella, 1964

Oral ciliature deep in buccal caviry, complex in conformation and comportment, with "watchglass organelle" (often accompanied by pigment mass) characteristically in viciniry; stomatogenesis parakinetal, regularly with oral replacement of parental mouthparts; preoral suture present, postoral less distinct; body size large, conspicuous in trophont-tomont stage; polymorphic life cycle, including cysts and palintomic reproduction; histophagous forms, generally feeding on moribund or wounded fresh-water invertebrates, though several species attack healthy fishes (marine as well as fresh-water) to host's eventual detriment.

With characteristics of suborder s.s. (above). Fresh-water, histophagous (occasionally parasitic) forms, with slender, inconspicuous theronts; number of tomites (produced within cyst) varies, 4-128.	Family OPHRYOGLENIDAE Kent, 1881
Oral ciliature possibly less complex than in ophryoglenids, but similar in many other characteristics; encysted tomont (away from host) can be of great size, producing hundreds (up to 2,000) tomites by palintomic fission; trophonts invade epithelial tissues of marine or fresh-water fishes, causing white spot disease; few species, but widespread distribution.	Family ICHTHYOPHTHIRIIDAE Kent, 1881