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such as Loxodes . 
Mutualism : kind of symbiotic relationship in 
which both partners benefit from the association, 
the host as well as the ecto - or endosymbiont ; veri-
fiable cases rare in which ciliates are the symbiont, 
but there are several in which the ciliate is the 
host (e.g., Omikron in Euplotes ; zoochlorellae of 
Paramecium ). 
Myoneme : fibrillar, ultimately filamentous, organelle 
with a known or presumed contractile function; in 
the broadest sense, may include the spasmoneme
found in the stalk of many peritrichs, the M-bands 
or M fibers coursing beneath or beside the kineties in 
the bodies of certain contractile heterotrichs , retrac-
tors and sphincters in various other groups, and still 
additional (micro)filamentous strands, bands, sheets 
or bundles active in contraction or retraction of all or 
part of a ciliate’s body; the fibrils, sometimes running 
deep in the cytoplasm, may be interconnected to one 
another, the pellicle, and/or certain kinetosomes . 
Naked : see Barren Kinetosome . 
Nasse : see Cyrtos . 
Nebenkörper : literally “neighboring body” and used
variously in protozoology; in the case of ciliates, 
it has been applied, formerly but now inappropri-
ately, to the parasomal sac , which is so often found 
in the near vicinity of kinetosomes. 
Neck : term used variously; the often highly exten-
sible region of the body that is immediately pos-
terior to the apical cytostome and corona in some 
 haptorians ; the non-extensible, sometimes quite 
elongate, part beneath the flared apical end of 
chonotrichs, but better called a collar . 
Nematocyst : not a preferred term; see Ortho-
nematocyst . 
Nematodesma (pl. Nematodesmata ): birefringent 
bundle of parallel microtubules , often showing a 
hexagonal, paracrystalline arrangement in cross-
section; typically, kinetosome -associated; plunging 
into the cytoplasm at right angles to the pellicle, 
forming with others the major reinforcements of 
the cytopharyngeal apparatus ( rhabdos and cyrtos ) 
of haptorians , nassophoreans , and cyrtophorines , 
but also found in other groups (e.g., in frontoniids); 
formerly identified with light microscopy as tri-
chites, cytopharyngeal rods, or the cytopharyngeal 
basket (Nd, Figs. 2.5B, 2.7j). 
Neoformation Organelle : a permanent tube-like 
invagination of the cell surface in which the oral struc-
tures of some oligotrichs (e.g., Pelagostrombidium ) 
develop; see Intracytoplasmic Pouch . 
Neoteny : retention of major larval characters in 
the mature or adult form ; the trophont of mobiline 
 peritrichs is sometimes considered a matured or 
permanently arrested telotroch (i.e., the larval form
in sessiline peritrichs). 
Neotype : single specimen designated as the name-
bearing type of a species; established when it is 
believed that no holotype , lectotype or syntype(s) 
Nephridial Apparatus : see Contractile Vacuole . 
Nephridial Canal : see Afferent Canal . 
Nephridioplasm : see Spongioplasm . 
Neritic : pertaining to the region of shallow water 
along a seacoast; the biotope near the shoreline 
edge of an ocean; to be contrasted with pelagic . 
Nesselkapseltrichocyste : see Toxicyst . 
40 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
Neuroformative System : see Neuromotorium . 
Neuromotor Apparatus : see Neuromotorium . 
Neuromotor Concept : see Neuromotorium . 
Neuromotorium : presumed center or cytobrain or 
motorium of a ciliate’s entire neuromotor apparatus 
(associated with the now discarded but once very 
popular Neuromotor Concept); a chromophilic 
fibrillar bundle formerly thought to play a con-
ductive or active coordinating role in locomotion, 
feeding, avoidance, and other behaviours; identi-
fied as the rest of the “neural” apparatus were 
various parts of the argyrome and/or structures 
today known to be microtubular or microfibrillar 
organelles of diverse sorts. 
Nomen Conservandum : name to be conserved; 
with appropriate permission, a name preserved as 
an exception to some provision of the International
Code of Zoological Nomenclature . 
Nomen Dubium : dubious or doubtful name; a 
name of uncertain application through lack of suffi-
cient information about it or the organism or taxon 
with which it might be associated. 
Nomen Novum : new name; a name expressly 
proposed and published as replacement of another 
name, usually a junior homonym requiring such 
action; often abbreviated to “nom. nov.” 
Nomen Nudum : “naked” name; a name published 
without description of its associated taxon; a diag-
nosis is necessary to validate both the name and 
taxon involved. 
Nomen Oblitum : forgotten name; a name unused 
as a senior synonym for more than 50 years; a long 
unused invalid name often literally “forgotten” by 
taxonomists of the group and generally best left in 
that condition. 
Nonciliferous Kinetosome : see Barren 
Kinetosome . 
Nonhomologous : the exact opposite of a homolo-
gous character ; however, either character may have 
an analogous function with some other structure. 
Nuclear Dualism : presence or existence of two 
different kinds of nuclei; for example, the micro - 
and macronucleus so characteristic of the great 
majority of ciliates; exhibition of the heterokaryo-
tic condition (Fig. 2.12). 
Nuclear Envelope : system of membranes or cov-
erings of a nucleus; composed of two unit mem-
branes , typically continuous with the endoplasmic
reticulum and often replete with minute pores. 
Nuclear Membrane : older term for nuclear enve-
lope . 
Nucleolus (pl. Nucleoli ): typically visible region 
of the nucleus where assembly of ribosomes is 
organized around the ribosomal RNA genes; see 
Endosome (Nuc, Fig. 2.12g, 2.12i). 
Nucleus (pl. Nuclei ): see Macronucleus and 
Micronucleus . 
Numbering Conventions : (1) Kineties are num-
bered – following the method of Chatton and 
Lwoff – around the body clockwise when viewed 
from the apical pole, with Kinety Number 1 , for 
example, being the rightmost postoral meridian , 
which, in certain hymenostomes , also bears the 
cytoproct posteriorly and is normally the stoma-
togenic kinety ; no matter the total number, the 
last one, immediately to the viewer’s right of 
Kinety Number 1 , is conventionally labelled as “n” 
(Fig. 2.7a, 2.7b, 2.7e). For counting kineties, the 
method of von Gelei, but subsequently generally 
ignored, gives results exactly the opposite from 
those of the Chatton and Lwoff system: Number 1 
is the same, but the suggested direction of count-
ing is counter-clockwise, and thus the Number “n” 
meridian is on the right rather than the left side of 
the first kinety. 
 (2) Microtubular triplets of a kinetosome are num-
bered – following the convention of Grain (1969) 
– clockwise around the proximal end of the basal 
body, viewed as in cross-section from the inside 
of the organism looking out, with Number 1 
being the triplet lying in the axis of the kinety, 
but it is often less ambiguous to make use of the 
location of the postciliary microtubules , which 
are assumed to be associated with Number 9, the 
last triplet (Fig. 2.1D). For counting kinetosomal 
triplets, the convention of Pitelka (1969) considers 
Numbers 1–3 to be on the right anterior margin of 
the kinetosome, looking at a cross-section from 
the base outward, and associated with the kine-
todesma (of Paramecium ); the counting similarly 
proceeds clockwise around the base. In the Pitelka 
convention, the triplet associated with the postcili-
ary microtubular ribbon is always number 5. This 
Glossary 41
equals Number 9 of the Grain convention, the system 
adopted in this book (Fig. 2.1D). 
Occam’s Razor : equivalent to the principle of 
parsimony, viz ., when faced with two or more 
hypotheses of equally explanatory value, choose 
the simplest. 
Ogival Field : transitory group of kinetosomes, bear-
ing thigmotactic cilia , which appear