Cap 17

Fabre-Domergue, 1888 
 – Plagiospira Issel, 1903 
 – Proboveria Chatton & Lwoff, 1936 
 – Protospirella Aescht, 2001 
 Family HYSTEROCINETIDAE Diesing, 1866 
 (syns. Ladidae , Protoptychostomatinae , Ptycho-
stom[at]idea , Raabellocinetinae ) 
 Size, medium to large; shape, elongate ovoid, 
somewhat flattened laterally; free-swimming, but 
typically attached to the host; somatic ciliation, 
holotrichous, dense; thigmotactic sucker, promi-
nent, essentially at apical end of left lateral sur-
face, comprised of segments of anterior kineties 
surrounded by a non-ciliated strip or field, often 
in a horseshoe shape and generally strength-
ened by fibers or other skeletal structures ; oral
region at posterior pole with paroral and three 
oral polykinetids, often reduced in size, with 
oral polykinetid 2 being two kinetosomes wide 
and in two segments – a peristomal segment 
around the posterior pole and an infundibular 
segment in the oral cavity proper ; reproductive 
methods include posterior budding or catenulation 
in some species; macronucleus, globular to ribbon-
like; micronucleus, may be multiple; contractile 
vacuole, may be multiple; cytoproct (?); bacte-
rivorous (?) and detritivorous; in freshwater and 
terrestrial habitats as commensals in the intestines 
of oligochaete annelids , with a few species of two 
genera ( Hysterocineta , Ptychostomum ) in the gut 
of certain freshwater snails ; 21 genera. 
NOTE : De Puytorac (1994f) and Ngassam, de 
Puytorac, and Grain (1994) have included this 
family and the Family Paraptychostomidae in 
the subclass Hysterocinetia . These two families 
are distinguished from other thigmotrich scutico-
ciliates by some astome -like features: an anterior 
sucker occurs in these two families and also in 
 haptophryid astomes ; and division by chain-for-
mation occurs in hysterocinetids (e.g., Kozloffia ) 
and some astomes (e.g., Family Haptophryidae , 
Family Radiophryidae ). Gene sequences will help 
to determine whether the hysterocinetids and par-
aptychostomids should be separated at this high 
taxonomic level or remain as families within the 
Order Thigmotrichida . 
 – Amieta Ngassam & Grain, 1998 
 – Coelothigma de Puytorac, 1969 
 – Coronthigma Jankowski, 1980 
 – Cotylothigma Raabe, 1949 
 – Craticuloscuta Kozloff, 1965 
 – Drilocineta Raabe, 1972 
 – Elliptothigma Meier, 1954 
 – Eminothigma Jankowski in Corliss, 1979 
 – Epicharocotyle Kozloff, 1965 
 – Hysterocineta Diesing, 1866 
 – Hysterocinetoides Ngassam & de Puytorac, 
1994 
 – Kozloffia de Puytorac, 1969 
 – Kysthothigma Raabe, 1949 
 – Metaptychostomum Ngassam & Grain, 1997 
 – Preptychostomum de Puytorac, 1969 
 – Proptychostomum Ngassam & Grain, 1997 
 – Protoptychostomum Raabe, 1949 
 – Ptychostomum Stein, 1860 
 – Raabellocineta de Puytorac, Grolière, & Grain, 
1979
 – Taeniocineta Raabe, 1972 
 – Thurstonia de Puytorac, 1969 
 Family PARAPTYCHOSTOMIDAE Ngassam, de 
Puytorac, & Grain, 1994 
 (syn. Paraptychostomatidae ) 
 Size, medium; shape, elongate ovoid, with 
extreme lateral flattening; free-swimming, but typi-
cally attached to host tissues; somatic ciliation, 
holotrichous, dense, of monokinetids; thigmotac-
tic sucker, prominent, essentially at apical end 
of left lateral surface, comprised of 7–9 short, 
isolated kineties and supported by cytoskeletal 
bundles ; oral region at posterior pole, extending 
as a cavity, inwards and anteriorly to the level 
of the equator with oral infraciliature as a paro-
ral and three oral polykinetids of which oral 
polykinetid 2 is continuous and of more than 
two files of kinetosomes wide ; macronucleus, 
elongate ellipsoid, orthogonal to the longitudinal 
axis of the cell; micronucleus, present; contractile 
vacuole, present; cytoproct (?); carnivorous on 
17.3 The Ciliate Taxa to Genus 423
other ciliates; in freshwater and terrestrial habitats 
as endocommensals in the digestive tracts of oligo-
chaete annelids (e.g., Alma ); one genus. 
 – Paraptychostomum Ngassam, de Puytorac, & 
Grain, 1994 
Incertae sedis in Order Thigmotrichida 
 Family NUCLEOCORBULIDAE Santhakumari & 
Nair, 1970 
 Size, large, up to 500 µm; shape, cylindroid, 
with posterior cellular extension of variable size; 
free-swimming, but highly thigmotactic; anterior
fixation sucker with its many kineties running 
nearly at right angles to longitudinal axis of the 
body and other somatic kineties ; oral ciliature 
appears to be at posterior pole, surrounded by long 
oral(?) cilia; macronucleus, huge, branching ; 
micronucleus (?); contractile vacuole (?); cytoproct 
(?); carnivorous on other ciliates; in marine habi-
tats in the mantle cavity of shipworms , species of 
 eulamellibranch molluscs of the genera Nausitora
and Teredo ; one genus. 
NOTE : This intriguing genus needs careful 
redescription.
 – Nucleocorbula Santhakumari & Nair, 1970 
 Family PROTANOPLOPHRYIDAE Miyashita, 
1929
 (syn. Protoanoplophryidae ) 
 Size, medium to large, up to 1,500 µm; shape, 
often elongate, laterally compressed and highly 
astomatid-like in appearance; free-swimming; pel-
licle, thickened; somatic ciliation, holotrichous, 
dense; anterior secant system in the form of an 
asymmetrical “ V” onto which somatic kineties 
insert with the suture area supported by fibers 
that condense to form a mucron at the tip of 
the “
V
” ; presumed oral region, located a short 
distance from the anterior pole, with no paroral, 
but bordered by two parallel “adoral” kineties ; 
division, sometimes by budding; macronucleus, 
ribbon-like; micronucleus, present; contractile 
vacuoles, numerous, in two rows ; cytoproct (?); 
osmotrophic (?), via a short canal that ends in a 
digestive vacuole (?); in freshwater habitats as 
endocommensals in the intestines of prosobranch 
 snails , such as the genus Bythinia ; one genus. 
 NOTE : Jankowski (2007) proposed the new 
order Parastomatida Jankowski, 2007 to include 
this unusual family.
 – Protanoplophrya Miyashita, 1929 
Incertae sedis in the Subclass Scuticociliatia 
 Family AZERIDAE Alekperov, 1985 
 Size, small; shape, ovoid; free-swimming; 
somatic ciliation, holotrichous; oral region, broad, 
displaced posteriorly, apparently with three oral 
polykinetids of which oral polykinetid 1 is tri-
angular and oral polykinetids 2 and 3 are rec-
tangles oriented transversely to the longitudinal 
axis of the oral region ; macronucleus, ellipsoid; 
micronucleus, present; contractile vacuole (?); 
cytoproct (?); feeding on bacteria and smaller pro-
tists; in freshwater habitats, but reported only once 
from a reservoir in Azerbaijan; one genus 
 – Azerella Alekperov, 1985 
 Subclass Hymenostomatia Delage & Hérouard, 1896 
 (syns. Homoiotricha p.p ., Hymenostom[at]orida , 
 Hymenostomida , Hymenostomina , Stichostomata 
p.p ., Tetrahymenophora s.s .) 
 Size, small to medium; shape, typically ovoid to 
elongate ovoid; somatic ciliation, typically holotri-
chous, often heavy, with preoral suture, but no posto-
ral one; caudal cilium, rarely found; somatic kinetids 
mostly monokinetids with dikinetids only at anterior 
tip of body; somatic extrusomes as mucocysts; oral 
region in anterior 1/4 of cell, when not absent alto-
gether, and usually inconspicuous; oral structures as 
a paroral dikinetid (i.e., haplokinety, stichodyad, 
undulating membrane) of only the b segment, 
which may be unciliated and reduced, and typi-
cally three oral polykinetids as membranelles ; 
stomatogenesis parakinetal ; division, free-swim-
ming or in cyst; contractile vacuole(s), present; cyto-
proct, present; bacterivorous with some carnivorous 
and some histophagous (e.g., Ophryoglena ) or para-
sitic (e.g., Ichthyophthirius , Ophryoglena ) forms; 
polymorphic life cycles especially characteristic of 
carnivorous and parasitic forms; predominantly in 
freshwater habitats; two orders. 
 Order Tetrahymenida Fauré-Fremiet in Corliss,