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(in the inter-
fissional stage); see Preoral kinety (Fig. 2.4O). 
Cirral Ciliature : see Cirrus . 
Cirromembranelle : name used by some workers 
for parts of the highly organized oral ciliature of 
certain colpodeans . 
Cirrus (pl. Cirri ): kind of compound somatic 
ciliature typical of hypotrich and stichotrich spiro-
tricheans , though not exclusively found there; a 
composite tuft of cilia, few to >100, functioning as 
a unit, though typically with no special enveloping 
membrane, and tapering distally or else fimbriate; 
its infraciliary kinetosomes are also interlinked and 
joined to other cirral bases by connecting fibers or 
tracts of microtubules; characteristically, a cirrus is a 
thick conical locomotor organelle, but some are also 
occasionally of aid in food-gathering; occurring in 
lines or in groups in definite patterns on the ventral 
surface, with subtypes identifiable by their location
(viz ., buccal, frontal, frontoventral, midventral, 
transverse (anal), caudal, and marginal) (Fig. 2.4M, 
2.4N; Cir, Figs. 2.3Aj, 2.3Al, 2.5Ab, 2.7k). 
Cisterna (pl. Cisternae ): see mention under 
Endoplasmic Reticulum and Golgi Apparatus . 
Clade : a monophyletic lineage. 
Cladistics : the branch of systematics devoted to 
identifying clades . 
Clathrocyst : cytoplasmic extrusome in Didinium
involved in production of the elaborate middle or 
mesocystic layer of the cyst wall (Fig. 2.9Cc). 
Clathrum : total abandonment of the term “clathrum” 
(Latin for “lattice”) is here proposed; see Rhabdos . 
Glossary 23
Clavate Cilium (pl. Cilia ): short immobile cilia
lacking the central pair of microtubules in their 
axoneme; allegedly sensory in function, occurring in 
a number of ciliates, typically in the brosse of hapto-
rian litostomes (e.g., Didinium ) and prostomes , but 
also present in the scopula of many peritrichs ; also 
called stereocilium ; see Condylocilium . 
Clonal Life Cycle : see Life Cycle, Clonal . 
Clone : population of organisms established by cul-
turing the descendants of a single individual. 
Cnidocyst : special kind of extrusome generally 
found in certain dinoflagellates but now (also) 
reported from several species of karyorelicteans ; 
in karyorelicteans, it appears to be a pear-shaped, 
laterally-flattened extrusome that contains a multiply 
coiled filament. 
Cnidotrichocyst : while a synonym for toxicyst , 
use of this term is not recommended. 
Code of Nomenclature : see International Code 
of Zoological Nomenclature . 
Collar : term used variously; the neck area between 
the often flared apical end and the body proper in 
 chonotrichs ; variously differentiated region beneath 
the opening in the lorica and used as a diagnostic 
characteristic in taxonomy (e.g. loricate peritrichs , 
 tintinnid spirotrichs ); an open or closed zone of oral 
polykinetids encircling the anterior end of choreot-
richs (Figs. 2.6B; Col, 2.8Ae, 2.8Af, 2.8Ah, 2.11Ca). 
Collarette : apical, peristomial lip that circumscribes 
the retractable epistomial disc in many sessiline 
 peritrichs ; equipped with a sphincter “muscle” (or 
Myoneme ) (Colt, Fig. 2.11B). 
Collecting Canal : see Afferent Canal . 
Colony : assemblage of cells derived by fission from 
a founder individual; see definitions under major 
types (i.e., Arboroid, Catenoid, and Spherical ) 
(Fig. 2.8A, 2.8B). 
Commensal : see Commensalism . 
Commensalism : a symbiosis in which the symbiont
benefits by the association but the host does not 
particularly suffer; endo- and ectocommensals 
exist in many groups; category sensu lato could 
include epibionts and symphorionts , typical forms 
in the life cycle of many attached or sessile ciliates, 
which live on the outside of their host; an inquiline
may be considered a special kind of endocom-
Compound Ciliary Organelle : see Compound
Ciliature . 
Compound Ciliature : general term for all cilia-
ture not comprised of single, separate or isolated 
individual cilia or of dikinetids of somatic cilia; 
various kinds, both somatic and oral in origin, 
occur throughout the phylum; particularly well 
developed in the spirotrichs (e.g. cirrus , mem-
branelle , polykinetid ). 
Compound Oral Ciliature : compound ciliature
found in the oral region . 
Compound Somatic Ciliature : compound cili-
ature found in the somatic region . 
Concrement Vacuole : curious and quite complex 
subpellicular cytoplasmic inclusion, one to an organ-
ism, containing refractile, probably mineral grains, 
having no opening, and sometimes strengthened by 
surrounding microtubules; characteristic of certain 
 trichostome endocommensals; function unknown, but 
considered by some workers as a kind of statocyst. 
Condylocilium (pl. Condylocilia ): kind of clavate
cilium found in hypotrich spirotrichs . 
Condylopallium : ovoid, bulb-like extension of 
the ventral right anteriormost part of the hypotrich 
 spirotrich Certesia , containing a vesicle with dense 
granules; function unknown, but perhaps excretory 
or statocyst-like. 
Conjugation : reciprocal-fertilization type of sexual 
phenomenon in which a meiotic/mitotic product of 
the micronucleus is typically reciprocally exchanged 
between the two individuals, except in total conju-
gation ; presumably occurs only between members 
of differing mating types; allegedly significant to 
both vitality of the clone and survival of the species, 
although the phenomenon is unknown (unobserved) 
in many ciliates from various groups; may involve 
 iso - or macro - and microconjugants , with temporary 
(most widespread) or total (as in all peritrichs and 
chonotrichs) fusion of members of the pair; pre- and 
exconjugant stages are recognized; the process is 
always followed by fission ( s ) of the exconjugants. 
Conocyst : a small, cone-shaped extrusome , prob-
ably a toxicyst , in the cortex of haptorians (e.g., 
Homalozoon and Loxophyllum ). 
24 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
Constellation of Characters Principle : use of mul-
tiple characters from diverse approaches or fields in 
assessment of differences or similarities between 
or among groups of organisms under comparative 
taxonomic study; its application helps overcome 
biases and prevents the extreme splitting likely when 
only very few characters – or data from but a single 
field – are used to draw conclusions concerning phylo-
genetic and taxonomic relationships. 
Contractile Vacuole ( CV ): liquid-filled organelle 
(sometimes multiple), serving as an osmoregulator in 
the cytoplasm of nearly all ciliates; generally pulsates 
with regular frequency under natural conditions: 
grows (diastole) to a certain size and then “contracts” 
(systole), typically emptying its contents, which may 
include dissolved “waste materials”, to the exterior 
via one or more pores; the CV is more widespread in 
ciliates than the ( cytoproct, CYP); synonymous, but 
non-preferred terms, are water expulsion vesicle and 
nephridial apparatus (CV, Fig. 2.9Bf). 
Contractile Vacuole Pore ( CVP ): minute perma-
nent opening in the pellicle , with argentophilic rim 
and a canal reinforced by microtubules through 
which contents of the contractile vacuole are 
expelled to the outside milieu; CVP’s are cortico-
type structures, characteristically stable in number 
and location and thus of diagnostic value in com-
parative taxonomy; also known by non-preferred 
term – expulsion vesicle pore (CVP, Figs. 2.3Ad, 
2.3Af, 2.3Ai, 2.4A, 2.4F, 2.4K, 2.7a, 2.7f, 2.7i, 
2.7k, 2.11Aa). 
Convergent Evolution : development of similar 
characters separately in two or more groups that 
do not share a close common ancestry; such 
characters, preserved by natural selection, arising 
through adaptation to similar ecological pressures 
or habitats. 
Corona (pl. Coronae ): apical, cytostome-bearing 
extremity of the body of certain haptorians ; often