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small to medium; shape, ovoid, flattened; 
free-swimming; cortical alveoli divided by trans-
verse grooves, elaborated into strikingly trap-
ezoidal and parallelogram shapes, filled with 
dense material ; somatic cilia, holotrichous or 
restricted to kineties lying in a dorsoventral groove 
that encircles the body; extrusomes as somatic 
mucocysts; oral cavity, conical, bordered or lined 
by extensions of somatic kineties; macronucleus, 
globular to ellipsoid; micronucleus, present; con-
tractile vacuole, present; cytoproct, present; feed-
ing on bacteria, starch grains, and smaller ciliates; 
in terrestrial habitats as endocommensals in the 
stomach of macropodid marsupials ; one genus and 
one genus incertae sedis . 
 – Macropodinium Dehority, 1996 
Incertae sedis in Family Macropodiniidae 
 – Megavestibulum Cameron & O’Donoghue, 
2003*
 Family POLYCOSTIDAE Cameron & 
O’Donoghue, 2003 
 Size, small to medium; shape, stout ovoid; 
free-swimming; somatic ciliation, holotrichous, 
with meridional kineties that can be separated 
by broad interkinetal ridges filled with many, 
small dense bodies (extrusomes?); oral cavity, a 
conical, round or flattened vestibulum in cross-
section, lined by extensions of some somatic 
kineties only along right side ; macronucleus, 
globular to ellipsoid; micronucleus, present; con-
tractile vacuole, one or more; cytoproct, present; 
feeding on bacteria and starch; in terrestrial habi-
tats as endocommensals in the forestomach of 
 macropodid marsupials ; one genus. 
 – Polycosta Cameron & O’Donoghue, 2003 *
 Class PHYLLOPHARYNGEA de Puytorac et al., 
1974
 (syn. Homotricha p.p .) 
 Size, small to large; shape, extremely variable, 
globular to ellipsoid to bizarre spinous and ten-
tacled forms; free-swimming and sessile or both, 
depending on the life cycle stages (e.g. free-swim-
ming dispersal larval forms of sessile chonotrichs 
and suctorians); alveoli, generally well-developed, 
especially on non-ciliated surfaces; somatic kine-
ties, typically arranged in two fields, which may be 
continuous over the body surface of ciliated stages; 
somatic kinetids as monokinetids that each 
have a lateral kinetodesmal fibril, a reduced or 
absent transverse microtubular ribbon, usually 
accompanied by a left-directed transverse fiber, 
and a somewhat convergent postciliary ribbon 
extended posteriorly to accompany ribbons of 
more anterior monokinetids; ribbon-like subki-
netal nematodesmata arise from somatic monok-
inetids, extending beneath kineties as subkinetal 
ribbons , which in cyrtophorids and chonotrichs 
probably extend anteriorly and in rhynchodids 
and suctorians probably extend posteriorly; extru-
somes vary with subclass (e.g., acmocysts in rhyn-
chodians; haptocysts in suctorian tentacles); oral
region with radially arranged microtubular rib-
bons, the phyllae, supporting the cytopharynx ; 
“cytopharynx” may be restricted to a tentacle in the 
suctoria or a tentacle-like tube in the rhynchodia; 
stomatogenesis, mixokinetal or merotelokinetal; 
macronucleus, homomerous in rhynchodians and 
380 17. The Ciliate Taxa Including Families and Genera
suctorians, and heteromerous in cyrtophorians and 
chonotrichs; conjugation, temporary or total, the 
latter may involve micro- and macroconjugants; 
micronucleus, single to many; contractile vacuoles, 
common; cytoproct, apparently absent in suctoria 
and many chonotrichs; feeding strategies, diverse, 
from algivorous and bacterivorous in cyrtophori-
ans to carnivorous on other ciliates in suctorians; 
encystment, common; in marine, freshwater, and 
terrestrial habitats, distributed widely, with many 
suctorian species as epibionts on a wide diversity 
of aquatic invertebrates and some vertebrates, 
 chonotrichs primarily restricted to the append-
ages of crustaceans , and rhynchodians typically as 
ectoparasites on invertebrates; four subclasses. 
NOTE : Grell and Meister (1982a) argued for 
two lineages within this clade that has phyllae 
lining the cytopharynx. One clade included the 
Subclasses Cyrtophoria and Chonotrichia , which 
have a heteromerous macronucleus and subkinetal 
microtubules that extend anteriorly beneath the 
somatic kineties. The other clade included the 
Subclasses Rhynchodia and Suctoria , which have 
toxic “oral” extrusomes, acmocysts and hapto-
cysts respectively, enclosed within an ingestatory 
tentacle(s), and have subkinetal microtubules that 
extend posteriorly beneath the somatic kineties. 
We have not recognized these two lineages in our 
classification, although preliminary molecular evi-
dence suggests that chonotrichs arose from within
the cyrtophorine clade with suctorians as a separate 
branch (Snoeyenbos-West, Cole, Campbell, Coats, 
& Katz, 2004). 
 Subclass Cyrtophoria Fauré-Fremiet in Corliss, 
1956
 (syns. Cyrtophorina p.p ., Cyrtohymenostomata p.p ., 
 Hypostomata , Hypostomatida , Phyllopharyngia , 
 Phyllopharyngidea p.p .) 
 Size, small to large; shape, frequently dorsoven-
trally flattened; free-swimming, may be sessile but 
usually not sedentary, often thigmotactic, some-
times using an adhesive organelle at the posterior 
end; alveoli, well-developed, revealed as a complex 
argyrome on the dorsal surface; somatic ciliature 
predominantly restricted to ventral surface with 
preoral suture skewed far to left and with right-
most somatic kinety often divided into a dorsal 
kinetofragment and a midventral kinetofrag-
ment; oral ciliature typically composed of one 
preoral kinety and two circumoral kineties as 
several short double files of kinetosomes located 
anteriad to the cytostome; cytopharyngeal appa-
ratus a complex cyrtos with phyllae surrounded 
by rod-shaped nematodesmata ; stomatogenesis, 
merotelokinetal, but involving extensive morphoge-
netic movements of preoral and circumoral kineties; 
macronucleus heteromerous; conjugation, tempo-
rary; feeding on bacteria and algae, with some para-
sitic species possibly ingesting epithelial tissues of 
host, such as fish ; in marine and freshwater habitats, 
broadly distributed, mostly marine, with numerous 
free-living forms and many epibionts of which a 
few species are parasites on fish ; two orders. 
NOTE : The genus Cyrtohymenostomata Das, 
Chatterjee, and Ray, 1969, which may be placed 
in the Subclass Cyrtophoria , is an unavailable 
name according to Aescht (2001) and therefore the 
Family Cyrtohymenostomatidae Jankowski, 1980 
would also be unavailable. 
 Order Chlamydodontida Deroux, 1976 
 (syns. Chilodonellida , Chilodonellina , Chlamydo-
dontina, Gymnozoida p.p. ) 
 Shape, typically dorsoventrally flattened, broad; 
free-swimming, but may attach to substrate by 
thigmotactic ventral somatic cilia; somatic kine-
ties typically ventrally disposed in two roughly 
equal fields, which may be separated midven-
trally (except in Family Kryoprorodontidae); 
without non-ciliated adhesive region or flexible 
podite ; six families. 
 Family CHILODONELLIDAE Deroux, 1970 
 (syn. Chilodontidae [for Odontohypotrichidae ], 
Phascolodontinae p.p.)
 Size, small to large; shape, width < 2/3 length, 
usually with pronounced anterior projection of 
body or “beak” extending to left; free-swimming 
(i.e., without lorica); somatic ciliation with right 
ventral somatic kineties arching preorally to left 
into “beak” so that the anterior preoral kinetal 
arcs of all right ventral somatic kineties are con-
tinuous with the more posterior parts of those 
kineties ; oral ciliature, typically as one preoral 
17.3 The Ciliate Taxa to Genus 381
and two circumoral kineties, but some variations; 
macronucleus, centric heteromerous, globular to 
ellipsoid; micronucleus, present; contractile vacu-
ole, present, may be multiple; cytoproct (?); feeding 
on bacteria and microalgae, but parasitic forms may 
feed on host tissues; in marine, freshwater, and ter-
restrial habitats, free-living but some Chilodonella
species as facultative parasites of