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of basal portion and cone-
shaped apex (Fig. 10.2). However, the cell body 
can reside on a stalk of considerable length, up 
to 600 µm in some Oxychonina species, while the 
neck can be extended and quite elongated in some 
Filichona species (Jankowski, 1973b). Suctorians , 
like chonotrichs , can be attached directly to the 
substrate or elevated off it on a stalk (Figs. 10.4–
10.6). In those species attached to the substrate, 
body form can be quite variable. Batisse (1994b) 
recognized five major morphological types (i.e., 
monaxon – Podophrya ; homaxon – Sphaerophrya ; 
radial – Cyclophrya ; bilateral – Stylophryodendron ; 
and irregular – Lernaeophrya , Dendrosoma ), but 
acknowledged it was not easy to classify a form 
unambiguously. This will be complicated further 
by any phenotypic plasticity exhibited by a species.
 The basic pattern for the somatic ciliature of the 
class is considered to be that of a free-living cyr-
tophorian , such as Chilodonella or Chlamydodon
10.3 Somatic Structures 221
Fig. 10.6. Stylized drawings of representatives of the 
Subclass Suctoria of the Class PHYLLOPHARYNGEA .
The endogenid Tokophrya and its bud . Note the so-called 
“ divergent kinety ” in the “posterior” half of the cell, 
which may be the homologue of the external right kinety 
of cyrtophorians 
(Fig. 10.1). The somatic ciliature, which is highly 
thigmotactic, is ventral and divided into a right 
field and a left field. Typically, the right field is 
more developed than the left field, arching ante-
riorly in front of the oral region over onto the left 
ventral surface (Fig. 10.1). On the right edge of the 
right field are the remnants of a kinety, called the 
 external right kinety ; one kinetofragment is located 
at the cell equator and the other is often located 
on the dorsal left surface. (Deroux, 1970, 1976a, 
1976b, 1977; Deroux & Dragesco, 1968). These 
 external right kineties , and the overall pattern of 
the ciliature, are also present in hypocomatid rhyn-
chodians , demonstrating their probable common 
ancestry with the cyrtophorians (Deroux, 1975). 
This general pattern of ciliature is also found in the 
 buds of chonotrichs (Dobrza ska-Kaczanowska, 
1963; Fahrni, 1984; Guilcher, 1951), suggesting 
an ontogenetic recapitulation of their common 
ancestry (cf. Figs. 10.1, 10.2). Finally, the somatic 
ciliature of the suctorian swarmer is believed to 
represent the right ventral ciliature of its cyrtopho-
rian (?) ancestor, the left field having been lost. The 
remaining right field then extends in a horse-shoe 
around the anterior end in some species while 
the whole ciliature has “slipped” to an equato-
rial position in other species, forming a girdle of 
ciliature (Figs. 10.3–10.6). Foissner and Foissner 
(1995) demonstrated by ultrastructural study that 
the “polarity” of these girdle kineties is trans-
verse rather than anterior-posterior in orientation. 
 Suctorian swarmers swim with the tentacles in the 
“rear” and the scopuloid , used for attachment going 
first! Are they swimming backwards or forwards? 
 A glycocalyx covers the plasma membrane 
of phyllopharyngeans , reaching its full develop-
ment in sessile forms (Fahrni, 1982; Henk, 1979; 
Sundermann & Paulin, 1985). This layer, which 
may function in prey capture, is very susceptible 
to fixation treatment and can be best demonstrated 
by either freeze-etching or ruthenium red staining, 
demonstrating its polysaccharide nature (Henk; 
Sundermann & Paulin). Underlying the plasma 
membrane is an alveolar layer that is typically con-
spicuous in members of this class, sometimes the 
 alveoli contain material (Grain & Batisse, 1974; 
Lom & Kozloff, 1968). The epiplasm is a consist-
ent feature of the phyllopharyngean pellicle, vary-
ing in thickness depending upon the region of the 
body. In some cyrtophorians , it can be somewhat 
thicker on the dorsal, non-ciliated surface, which is 
also underlain by triads of microtubules (Kurth & 
Bardele, 2001). The dorsal surface of rhynchodi-
ans can be underlain by many layers of micro-
tubules (Lom & Kozloff, 1970). The epiplasm 
can be more than 1 µm thick in some chonotrichs 
(Fahrni, 1982; Karadzhan, 1976) and suctorians 
(Grell & Benwitz, 1984; Grell & Meister, 1982b). 
Pores penetrate through the non-ciliated pellicle of 
 chonotrichs and suctorians , and there may be over 
100,000 on an average Spirochona (Fahrni, 1982). 
These pores are sites of active pinocytosis in suc-
torians , providing the ciliate with macromolecules 
from the medium (Rudzinska, 1980). 
 It was the structure of the somatic kinetid 
that convinced Small and Lynn (1981) to 
unite these four major groups into the Class 
 PHYLLOPHARYNGEA , based on the descrip-
tions of several pioneering studies (e.g., Batisse, 
1973; Grain & Batisse, 1974; Lom & Corliss, 
1971; Lom & Kozloff, 1970; Sołty ska, 1971). 
The characterization of the kinetid by Lynn (1981, 
1991) is supported by recent descriptions (Foissner 
& Foissner, 1995; Kurth & Bardele, 2001). The 
 phyllopharyngean monokinetid is as follows: a 
slightly convergent postciliary ribbon at triplet 9, a 
short, rapidly tapering and laterally directed kine-
todesmal fibril at triplets 5 and 6, and a transverse 
fibre at triplet 3 (Fig. 10.7). Transverse micro-
tubules may be associated with triplet 4 in some 
taxa (e.g., Chlamydodon – Kurth & Bardele, 2001; 
Spirochona – Fahrni, 1982; Hypocoma – Grell & 
Meister, 1983) (Fig. 10.7). The postciliary micro-
tubules typically extend to overlap each other in a 
“triad” arrangement, accompanying other ribbons 
in the right cortical ridge, while the transverse 
microtubules, when present, extend slightly poste-
riorly and laterally to support the left cortical ridge 
(Fig. 10.8). Parasomal sacs typically occur on the 
right side of the kinetosome, but may also occur 
on the left (Fig. 10.7) (see Lynn, 1991). Finally, 
 subkinetal microtubules originate as a flat ribbon 
from the base of the kinetosome and extend anteri-
orly beneath those originating from more anterior 
kinetosomes (Kurth & Bardele, 2001; Lynn, 1991). 
Their orientation in some suctorians cannot be 
concluded with precision given the unusual orien-
tations of their somatic kineties. 
 Small mucocysts are distributed throughout the 
ciliated cortex of cyrtophorians (Kurth & Bardele, 
2001) and rhynchodians (Lom & Kozloff, 1970). 
Some dysteriid cyrtophorians have well-developed 
 podites that are used for attachment to substrates 
(Deroux, 1975; Fauré-Fremiet, André, & Ganier, 
1968a). Other cyrtophorians and hypocomatids 
have a posterior “attachment” region, a portion of 
the somatic cortex with some associated kineties 
with densely spaced kinetosomes and a secretory 
pellicular area (Deroux, 1975). Abundant secre-
tory vesicles , likely containing a mucoprotein, are 
found in the holdfast organelle of cyrtophorians 
(Lom & Corliss, 1971; Fauré-Fremiet et al., 1968a) 
and chonotrichs (Fahrni, 1984) where they provide 
 substances for the temporary attachment structures 
and for the basal disc and stalk , respectively. The 
 scopuloid is likely the homologous structure in 
the suctorians . Secretions from vesicles in the 
 scopuloid provide material for the basal disc, 
non-contractile stalk , and, in some species, the 
 lorica . A thin dense outer layer surrounds a stalk 
matrix, which is highly variable in appearance: 
it can be composed of fibres that are periodically 
striated (e.g., Acineta – Batisse, 1967a; Acinetopsis
– Grell & Meister, 1982b; Thecacineta – Batisse, 
1969) or mostly not (e.g., Tokophrya – Batisse, 
1970). The stalk is a highly resistant structure com-
posed of proteins and sulfate groups, possibly also 
 polysaccharides , and it can represent up to 15% 
of the total protein of the cell (Hascall, 1973). In 
loricate forms,