Cap 10

the lorica can cover a portion or the 
entire cell body. Sometimes it is an extension of the 
outer covering of the stalk with loose fibrous mate-
rial “gluing” it to the cell body (Batisse, 1967a; 
Bardele, 1968). The lorica or “shell” of Metacineta
species has an exceedingly complex crystalline 
nodal substructure (Batisse, 1967b). 
Fig. 10.7. Schematics of the somatic kinetids of the Class PHYLLOPHARYNGEA . ( a ) Monokinetid of the cyr-
tophorian Chilodonella . ( b ) Monokinetid of the cyrtophorian Brooklynella . ( c ) Monokinetid of the chonotrich
Chilodochona . ( d ) Monokinetid of the chonotrich Spirochona . ( e ) Monokinetid of the rhynchodian Hypocoma . ( f ) 
Monokinetid of the rhynchodian Ignotocoma . ( g ) Monokinetid of the suctorian Trematosoma . ( h ) Monokinetid of the 
 suctorian Trichophrya (from Lynn, 1981, 1991) 
10.3 Somatic Structures 223
224 10. Subphylum 2. INTRAMACRONUCLEATA: Class 4. PHYLLOPHARYNGEA
 Mitochondria are the typical tubular mitochon-
dria. Batisse (1994b) reported that Allantosoma , 
the endosymbiotic suctorian of the horse cecum , 
contains hydrogenosomes , while Foissner and 
Foissner (1995) described hydrogenosomes in 
Enchelyomorpha , an anaerobic suctorian collected 
from domestic sewage . 
 Contractile vacuoles are present throughout the 
class. Indeed, the sessile habit of suctorians made 
them fruitful models for our basic understanding 
of contractile vacuole function in the protozoa 
(Kitching, 1967). Patterson (1980) characterized 
them as having an irregular network of spongiome 
tubules, and this has been confirmed for the chonot-
richs (Fahrni, 1983; Karadzhan, 1976). Contractions 
of the vacuole of Heliophrya were correlated with 
spontaneous depolarizing potentials of the plasma 
membrane (Eagles, Gregg, & Spoon, 1980). 
 The cytoproct is found in cyrtophorians , chonot-
richs , and rhynchodians . In cyrtophorians it is 
not a defined area, but egestion typically occurs 
through the right posterior dorsal surface (Deroux, 
1994a). In the chonotrich Spirochona , the cyto-
proct opens at the base of a 20 µm long “excretory” 
canal (Fahrni, 1983). The rhynchodian Hypocoma
has a cytoproct canal about 1 µm long (Grell & 
Fig. 10.8. Somatic cortex of a typical phyllopharyngean cyrtophorian whose postciliary microtubules extend as 
“triads” alongside each other into the right cortical ridges. Note that the transverse microtubules extend slightly pos-
teriorly into the left cortical ridge. (Adapted from Sołty ska, 1971.)
Meister, 1983). As noted above, suctorians do not 
have a cytoproct , but they may dispose of wastes 
by pinching off portions of the cytoplasm that are 
laden with wastes. 
 10.4 Oral Structures 
 The phyllopharyngeans represent a class where 
there is dramatic adaptive divergence in the struc-
tures of the oral region related to very different 
feeding functions. Nevertheless, their common 
ancestry is supported both by the strong simi-
larities in the somatic kinetids (see above Somatic 
Structures ) and by the presence of phyllae , or arm-
bearing microtubular ribbons, lining the ingestatory 
apparatus, either as a true cytopharynx or a tentacle 
(see Lynn & Foissner, 1994). Cyrtophorians tend to 
be substrate-oriented, encounter feeders , ingesting 
single diatoms or several bacteria at once as they 
“browse” along the substrate (Epstein & Shiaris, 
1992; Sawicka, Kaczanowski, & Kaczanowska, 
1983). Chonotrichs are suspension feeders , using 
the entire ciliature, both somatic and oral, which 
lines the oral cone, to create feeding currents to 
bring particles to the cytostome. Rhynchodians and 
 suctorians both have suctorial tube-like oral struc-
tures or tentacles. Rhynchodians are encounter 
feeders, attaching to the host, whether it be another 
 ciliate or a metazoan . Their haptotrichocysts in 
their suctorial tube function in some fashion, not 
yet known, to aid ingestion of host cytoplasm. 
 Suctorians can be characterized as passive encoun-
ter feeders – they are either sessile or float freely 
“waiting” for prey to contact the feeding tentacles . 
If appropriate, this contact will elicit extrusion of 
the toxic haptocysts that ensure fusion of predator-
prey cells and paralysis of the prey (see below; 
Hausmann, 1978). 
 Cyrtophorians have an oral region that is typi-
cally bordered on its right by two circumoral
kineties or kinetofragments and anteriorly by a 
 preoral kinety or multiple preoral kinetofragments 
(Fig. 10.1). However, there is considerable vari-
ation on this “basic” plan: the dysteriid Pithites
may have 5 or more small kinetofragments sur-
rounding the cytostome while some Lynchella
species may have oral kinetofragments that extend 
almost across the entire ventral surface of the 
cell (see Deroux, 1970, 1976a, 1977; Deroux & 
Dragesco, 1968). Early ultrastructural observa-
tions demonstrated the inverted nature of these 
oral kineties, predicted by their counter-clockwise 
migration occurring during cell division (Lom & 
Corliss, 1971; de Puytorac & Grain, 1976) (see 
below Division and Morphogenesis ). Subsequent 
descriptions have confirmed this (Hofmann, 1987; 
Hofmann & Bardele, 1987). These oral kinetids 
are characterized as follows: a ‘posterior’ or right-
most ciliated kinetosome with which are associated 
a slightly convergent postciliary ribbon and occa-
sionally a transverse fibre; and an ‘anterior’ or 
left-most, non-ciliated kinetosome with which is 
associated a transverse fibre (Lynn, 1981; Grain, de 
Puytorac, & Bohatier, 1973). Parasomal sacs may 
occur on either side of these kinetosomes and addi-
tional dense fibres may be present (see Hofmann, 
1987; Hofmann & Bardele, 1987). These oral 
kinetofragments are associated with the cyrtos , the 
complex cytopharyngeal “basket” of these ciliates, 
which shares strong similarities to the oral bas-
ket of nassophoreans (see Chapter 11 ). It is not 
certain that the cyrtos in both groups represents 
a demonstration of deep common ancestry or of 
convergent evolution. Although phylogenies based 
on small subunit ribosomal RNA genes clearly 
separate phyllopharyngeans and nassophoreans 
(see Strüder-Kypke, Wright, Fokin, & Lynn, 2000b), 
they are nevertheless topologically close on these 
trees suggesting the cyrtos could be homologous. 
In addition to the palisade of nematodesmata, three 
groups of microtubular ribbons (i.e., cytostomal or 
 cytopharyngeal or Z lamellae ; subcytostomal or Y 
 lamellae ; and nematodesmal or X lamellae , Eisler, 
1988; Kurth & Bardele, 2001; Tucker, 1968) are 
associated with the cyrtos . Two of these, the Y 
and Z lamellae, are shared by nassophoreans and 
 cyrtophorians . Ingestion is likely aided by dense 
differentiations at the outermost ends of the oral 
nematodesmata, variously called capitula , “teeth”, 
“maxillae”, or dens, while the arm-bearing micro-
tubules of the cytopharyngeal lamellae propel 
food vacuole membrane enclosing food into the 
endoplasm (Tucker, 1972). A system of complex 
elongated tubules, found also in chonotrichs, is 
associated with the cyrtophorian cyrtos . These 
may function in food vacuole formation, although 
direct evidence for this hypothesis is still needed 
(Chilodonella – Pyne & Tuffrau, 1970; chonotrichs 
– Fahrni, 1982; Grain & Batisse, 1974). 
10.4 Oral Structures 225
226 10. Subphylum 2. INTRAMACRONUCLEATA: Class 4. PHYLLOPHARYNGEA
 As suspension feeders , chonotrichs engage the 
entire body ciliature in creating feeding currents. It 
is therefore likely that there have not been strong 
selective pressures to retain an organized and adap-
tive oral ciliature. Indeed, it was only through elec-
tron microscopy that the chonotrich Chilodochona
was shown to have an oral ciliature. Grain and 
Batisse (1974) described a single inverted oral 
kinety composed of dikinetids patterned identically