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over right 
lateral and ventral surfaces ; somatic extrusomes 
as rod-shaped mucocysts, not fibrocysts; oral cav-
ity, anterior, with three small oral polykinetids and 
a paroral of reduced size; macronucleus, globular; 
micronucleus, present; contractile vacuole, present; 
microphagous; in marine habitats, benthic; two 
NOTE : This family has been placed here for 
some time, a placement that requires confirmation 
by molecular genetic analysis since the ultrastruc-
ture of this ciliate shows no clear affinities to other 
 – Discotricha Tuffrau, 1954 
 – Lopezoterenia Foissner, 1997 
 Family LEPTOPHARYNGIDAE Kahl, 1926 
 (syns. Pseudomicrothoracidae , Trichoderidae [for 
 Trichopelm(at)idae ]) 
 Size, small; shape, ovoid, slightly flattened; 
pellicle thrown into obvious cortical ridges, under-
lain by well-developed epiplasm; free-swimming; 
somatic ciliation, holotrichous, but sparse; left
border of oral region has perioral somatic 
kinety of dikinetids and right border has three 
oral polykinetids ; cyrtos, long, tubular, in ante-
rior 1/3 of body ; macronucleus, globular to ellip-
soid; micronucleus, present; contractile vacuole, 
present; microphagous, on bacteria and micro-
algae, including cyanobacteria , even filamentous 
forms; in freshwater and terrestrial habitats, such 
as mosses; two genera. 
 – Leptopharynx Mermod, 1914 
 – Pseudomicrothorax Mermod, 1914 
 Family MICROTHORACIDAE Wrzesniowski, 1870 
 (syns. Conchophryidae , Drepanomonadidae , 
 Trochiliopsidae ) 
 Size, typically very small; shape, crescentic and 
flattened; free-swimming; somatic ciliation, very 
sparse, typically with three right preoral somatic 
kineties, usually of dikinetids, anterior to oral 
region, and left somatic kineties very reduced ; 
oral region, variable in position, anterior in some 
genera (e.g. Stammeridium ) and displaced to the 
posterior in others (e.g. Microthorax ); typically a 
reduced paroral and three small oral polykinetids 
confined to the oral cavity; macronucleus, globular; 
micronucleus, present; contractile vacuole, present; 
microphagous; in terrestrial habitats, especially 
mosses; four genera and two genera incertae sedis . 
 – Drepanomonas Fresenius, 1858 
 – Microthorax Engelmann, 1862 
 – Stammeridium Wenzel, 1969 
 – Trochiliopsis Penard, 1922 
Incertae sedis in Family Microthoracidae 
 – Conchophrys Chatton, 1911 
 – Hexotricha Conn in Conn & Edmondson, 1918 
Incertae sedis in Class NASSOPHOREA 
 Order Colpodidiida Foissner, Agatha, & Berger, 2002 
 Size, small; shape, elongate, ovoid; free-
swimming; somatic ciliation, holotrichous, with 
slight twist to kineties in anterior end; oral region 
in middle 1/3 of cell, with a paroral and three 
oral polykinetids that can be reduced in size 
to only one or two kinetosomes; cytostome-
cytopharynx, supported by a delicate cyrtos 
(?), which extends anteriorly, then dorsally and 
posteriorly ; stomatogenesis, mixokinetal; macro-
nucleus, globular to ellipsoid, may be as two nod-
ules; micronucleus, present; contractile vacuole, 
present; cytoproct, present; feeding on bacteria and 
flagellates; in terrestrial habitats, particularly saline 
soils; one family. 
NOTE : Foissner, Agatha, and Berger (2002) 
report that their cytological stained preparations 
suggest the presence of alveolocysts, a diagnostic 
feature of two orders in the class, and they provide 
clear evidence for nassophorean features in the 
stomatogenesis of these forms. The placement of 
this family requires confirmation by ultrastructural 
and molecular genetic analyses. 
 Family COLPODIDIIDAE Foissner, 1995 
 With characteristics of the order; three genera. 
 – Apocolpodidium Foissner, Agatha, & Berger, 2002 *
 – Colpodidium Wilbert, 1982 
400 17. The Ciliate Taxa Including Families and Genera
 – Pedohymena Foissner, 1995 
 – Phagoon Foissner, Agatha, & Berger, 2002 
 – Pseudocolpodidium Foissner, Agatha, & Berger, 
 Class COLPODEA Small & Lynn, 1981 
 (syns. Bryometopia , Colpodia , Rimostomata p.p ., 
 Transversala p.p ., Stichofragmina p.p .) 
 Size, small to large; shape, variable, but often 
somewhat twisted; free-swimming with a few species 
building gelatinous loricae; alveoli, typically well-
developed and revealed as a prominent argyrome, 
typically reticulated ; somatic kineties of dikinetids 
with a cilium on each kinetosome; somatic diki-
netids having one transverse microtubular ribbon 
and at least one postciliary microtubule associated 
with the anterior kinetosome, and one transverse 
ribbon, one postciliary ribbon, and one short 
kinetodesmal fibril, directed towards the right, 
associated with the posterior kinetosome; poste-
rior transverse ribbons of microtubules extending 
posteriorly and overlapping one another as the 
LKm fibre or transversodesma ; parasomal sacs, 
from two to four, on both sides of kinetid; somatic 
extrusomes as saccular or rod-shaped mucocysts; 
oral structures based on a paroral of dikinetids on the 
right and one to many square-packed polykinetids 
on the left, but variations from this pattern character-
ize included taxa; stomatogenesis, mero- or pleu-
rokinetal; fission, often palintomic in a reproductive 
cyst; macronucleus, homomerous, sometimes with 
single large nucleolus; conjugation, reported only 
for bursariomorphids; contractile vacuole, typically 
posterior, with collecting canals in some larger cells; 
resting cysts common; feeding, highly variable, with 
small-sized cells as bacterivores and larger cells as 
algivores and carnivores; in freshwater and terrestrial 
habitats, rarely marine; six orders. 
NOTE : Foissner (1993a) has written an outstand-
ing and authoritative monograph on this group. 
Foissner (1993a, 1994b) has divided this class into 
the subclasses Colpodia and Bryometopia based 
primarily on characteristics of the argyrome. The 
argyrome can be a variable feature of cells, chang-
ing with their physiological state. Thus, before we 
accept this subdivision, we await corroboration of 
the taxonomic significance of this trait by other 
kinds of data, such as gene sequences. 
 Order Bryometopida Foissner, 1985 
 Size, small to large; shape, ovoid; argyrome, 
“kreyellid type”, a very highly reticulated, subdi-
vided dense network ; somatic kineties, slightly spi-
ralled; oral region subapical to equatorial with paroral 
of dikinetids or multiple kinetosomes on right extend-
ing to right posterior region of the oral cavity and 
usually several left oral polykinetids; stomatogenesis, 
pleurotelokinetal; fission may be in reproductive cyst; 
four families and one family incertae sedis . 
NOTE : Foissner (1993a, 1994b) established this 
taxon based on the character of the argyrome of the 
included families. We have united these families in 
this order despite our concerns noted above about the 
significance of this character to establish a class. The 
order needs corroboration using other characters. 
 Family BRYOMETOPIDAE Jankowski, 1980 
 (syn. Thylakidiidae ) 
 Size, small to large; shape, ovoid; free-swim-
ming; somatic ciliation, holotrichous, forming 
a conspicuous postoral suture ; oral region, large 
relative to body size; paroral typically extending 
along right border of oral cavity; left serial oral 
polykinetids conspicuous, typically more than 10, 
extending along left side of oral cavity ; macronu-
cleus, globular to ellipsoid; micronucleus, may be 
multiple; contractile vacuole, present; cytoproct (?); 
feeding on bacteria and algae; in freshwater and ter-
restrial habitats; two genera. 
 – Bryometopus Kahl, 1932 
 – Thylakidium Schewiakoff, 1893 
 Family JAROSCHIIDAE Foissner, 1993 
 Size, small to medium; shape, elongate, ovoid; 
free-swimming; somatic ciliation, holotrichous; 
oral region anterior with several differently 
structured kinetidal elements – at least includ-
ing right kinetofragments, seemingly derived 
as extensions of somatic