Cap 17

dense, with 
longer bristle-like cilia interspersed between 
regular cilia, and kineties having prominent pre-
oral and postoral secant systems ; oral region, an 
expansive and deep groove, with the posterior 
end of the paroral as an enlarged kinetosomal 
field, almost “polykinetid”-like, and oral polyki-
netids only on anterior 1/3–1/2 of oral region, 
and oblique to long axis of oral area ; macronu-
cleus, globular to elongate ellipsoid, sometimes 
multiple; micronucleus, present; contractile vacu-
ole, present; cytoproct, present; microphagous on 
bacteria and algae; in marine and freshwater habi-
tats, often planktonic; one genus and one genus 
incertae sedis . 
NOTE : The description of this family will need 
to be modified if Sulcigera is confirmed to be a 
member. 
 – Histiobalantium Stokes, 1886 
Incertae sedis in Family Histiobalantiidae 
 – Sulcigera Gajewskaja, 1928 
 Family PENICULISTOMATIDAE Fenchel, 1965 
 Size, medium; shape, reniform, strongly flat-
tened laterally; free-swimming; somatic ciliation, 
holotrichous, dense, with preoral and postoral 
secant systems; oral region, on ventral margin 
with long paroral, the anterior segment of the 
long, linear oral polykinetid 2 of >2 files of 
kinetosomes, and the posterior segment of oral 
polykinetid 2 oriented transversely to the lon-
gitudinal axis of the oral cavity ; macronucleus, 
ellipsoid, relatively large; micronucleus, may be 
multiple; contractile vacuole, present; cytoproct, 
present; bacterivorous (?); in marine and fresh-
water habitats as endocommensals in the mantle 
cavity of bivalve molluscs and in the intestines of 
certain sea urchins ; three genera. 
 – Echinosociella Berger in Small & Lynn, 1985 
 – Mytilophilus Antipa & Dolan, 1985 
 – Peniculistoma Jankowski, 1964 
 Family PLEURONEMATIDAE Kent, 1881 
 (for Aphthoniidae ; syn. Larvulinidae (?) ) 
 Size, small to large; shape, ovoid; typically free-
swimming; somatic ciliation, holotrichous; caudal 
cilia or bristles, long, stiff; somatic extrusomes as 
prominent, rod-shaped mucocysts; oral region, 
shallow groove, occupying much of ventral 
surface, dominated by paroral cilia, present as 
a stiff velum and distinctly curling around the 
subequatorial cytostome; oral polykinetid 2, 
typically as two distinct segments or derived 
from two segments – a long, linear, anterior 
segment with no more than two files of zig-zag 
kinetosomes, and a posterior segment, typically 
“V”-shaped ; macronucleus, globular to ellipsoid; 
micronucleus, present; contractile vacuole, present; 
cytoproct, present; algivorous and bacterivorous; 
in marine and freshwater habitats, occasionally 
associated with some invertebrates as an ectocom-
mensal (e.g., Pleurocoptes on hydractinian coe-
lenterates); four genera. 
 – Gajewskiella Obolkina, 1989 
 – Pleurocoptes Wallengren, 1896 
 – Pleuronema Dujardin, 1841 
 – Schizocalyptra Dragesco, 1968 
 Family THIGMOCOMIDAE Kazubski, 1958 
 Size, small; shape, ovoid, flattened laterally, 
bluntly tapered posteriorly; free-swimming; 
somatic ciliation, reduced, as relatively densely 
ciliated anterior kinetofragments with clearly 
delineated area of thigmotactic ciliature on the 
concave lateral left surface and posterior half 
17.3 The Ciliate Taxa to Genus 421
of body sparsely ciliated with incomplete left 
lateral somatic kineties ; oral region, equatorial, 
with short paroral and a large oral polykinetid, 
broader anteriorly and tapering posteriorly ; 
macronucleus, globular; micronucleus, present; 
contractile vacuole, present; cytoproct (?); feeding 
(?); in terrestrial habitats as endoparasites (?) in 
the renal organ of snails , such as Oxychilus ; three 
genera.
 – Baikalothigma Jankowski, 1982 
 – Cotensicoma Jankowski, 1982 
 – Thigmocoma Kazubski, 1958 
Incertae sedis in Order Pleuronematida 
 – Larvulina Penard, 1922 
 Order Thigmotrichida Chatton & Lwoff, 1922 
 (syns. Arhynchodina , Diplohymenina , Hemispeirina 
p.p ., Hysterocinetia p.p ., Hysterocinetida p.p ., 
 Hysterocinetina p.p ., Parastomatida , Parastomatina , 
 Protoptychostomatina p.p ., Stomatina , Stomodea , 
 Thigmotricha , Thigmotrichina ) 
 Size, small to medium; shape, ovoid to elon-
gate ovoid, laterally compressed in many species 
and with an anterior sucker in some species; 
free-swimming, but highly thigmotactic, attached 
to host tissues by thigmotactic cilia; somatic cili-
ation, uniform, frequently dense; thigmotactic 
cilia as anterior differentiations of somatic 
kineties, sometimes in a separate field ; oral 
ciliature mostly subequatorial in location, 
often spiraled around the posterior pole of the 
body, where the cytostome is located, or at the 
posterior pole but in reduced form ; paroral not 
forming a prominent velum; ribbed wall, incon-
spicuous or absent; oral polykinetid 3 reduced 
or absent ; stomatogenesis of opisthe oral struc-
tures involving kinetosomes of proter’s paroral 
and scutica; bacterivorous (?) or detritivorous 
(?); in marine and freshwater habitats as com-
mensals with one major group widely occurring 
in lamellibranch molluscs , and another mainly in 
 oligochaete annelids , although other hosts occa-
sionally involved; four families and two families 
incertae sedis . 
NOTE : Chatton and Lwoff (1949, 1950) remain 
the classical works on this group. However, the 
monographic papers of Raabe (1967, 1970a, 1971a, 
1971b, 1972), the latter published posthumously, 
should be consulted as the most recent revisionary 
works. 
 Family ANCISTRIDAE Issel, 1903 
 (syns. Ancistrumidae , Boveriidae , Protophryidae ) 
 Size, small to medium; shape, ovoid, occasion-
ally elongate; free-swimming, but typically attached 
to the host; somatic ciliation, holotrichous, with 
thigmotactic ciliature, anterior dorso-lateral 
left, not set apart from other somatic kineties; 
oral region, extending nearly length of body, 
with cytostome presumed to have moved pro-
gressively posterior-poleward as genera diversi-
fied; oral ciliature, conspicuous, winding in arc 
of >360° around antapical pole in some species, 
with oral polykinetid 2 long and terminating 
anterior to the cytostome ; macronucleus, globu-
lar to ellipsoid; micronucleus, present; contractile 
vacuole, present; cytoproct (?); bacterivorous (?); 
in marine and freshwater habitats as commensals in 
the mantle cavity and less often, intestine of mol-
luscs , such as prosobranch limpets , pulmonates , 
and lamellibranchs ; eight genera. 
 – Ancistrella Cheissin, 1931 
 – Ancistrum Maupas, 1883 
 – Ancistrumina Raabe, 1959 
 – Fenchelia Raabe, 1970 
 – Protophyra Kofoid, 1903 
 – Protophyropsis Raabe, 1959 
 – Semiboveria Raabe, 1970 
 – Syncilancistrumina Knight & Thorne, 1982 
 Family HEMISPEIRIDAE König, 1894 
 Size, small; shape, ovoid, occasionally elongate; 
free-swimming, but typically attached to the host; 
somatic ciliation, holotrichous, but reduced to 
a smaller number of spiraled kineties in many 
species, becoming oblique and even almost hori-
zontal in some; thigmotactic area, distinct, of 
reduced dorsal kineties enclosed in a secant 
system, very pronounced in certain genera ; oral
region in posterior 1/3 of body, with its ciliature, 
often reduced, with oral polykinetid 2, at least, 
hook-like to strongly curved, looping behind 
the cytostome and, in the extreme, curving to 
well over half-way around the posterior pole ; 
macronucleus, globular to ellipsoid; micronucleus, 
present; contractile vacuole, present; cytoproct (?); 
422 17. The Ciliate Taxa Including Families and Genera
bacterivorous (?) and detritivorous; in marine and 
freshwater habitats as commensals in the mantle 
cavity of molluscs , on the integument of certain 
 echinoderms or in the respiratory trees of holothu-
rian echinoderms ; seven genera. 
 – Ancistrospira Chatton & Lwoff, 1926 
 – Boveria Stevens, 1901 
 – Cheissinia Chatton & Lwoff, 1949 
 – Hemispeira