Cap 10

” 
of the ancestral suctorian , preserved in the cecum 
of a vertebrate?! Finally, Foissner and Foissner 
(1995) conclusively demonstrated using electron 
microscopy that the strange tentacled “ haptorian ” 
Enchelyomorpha was, in fact, the swarmer of a 
small globular suctorian , based on the substruc-
ture of its tentacles and a complete study of its 
life cycle. 
 10.5 Division and Morphogenesis 
 Guilcher (1951) consolidated our current view 
that the subclasses in this class might be phyloge-
netically related with her descriptions of division 
morphogenesis , which Dobrza ska-Kaczanowska 
(1963) later confirmed. Foissner (1996b) charac-
terized stomatogenesis of cyrtophorians as mero-
telokinetal because the opisthe anlagen form at the 
anterior ends of a small number of somatic kineties 
(Fig. 10.9). He does not characterize stomatogen-
esis for the other three subclasses because no oral 
ciliature has been described in these ciliates. 
 Stomatogenesis in cyrtophorians involves a coun-
ter-clockwise migration of the kinetofragments, 
when the ventral surface is viewed from outside the 
cell (Fig. 10.9). Thus, at completion of stomatogen-
esis , these three or more oral kinetofragments are 
inverted with respect to neighbouring somatic kine-
ties (Deroux, 1970, 1976a, 1977; Sniezek & Coats, 
1996). These movements have been confirmed and 
the interpretation of the inverted nature of the oral 
dikinetids in cyrtophorians has been verified by the 
10.5 Division and Morphogenesis 227
228 10. Subphylum 2. INTRAMACRONUCLEATA: Class 4. PHYLLOPHARYNGEA
detailed ultrastructural study of Trithigmostoma
(Hofmann & Bardele, 1987) and Chilodonella
(Hofmann, 1987). Kurth and Bardele (2001) verify 
the same pattern in Chlamydodon and put forward 
the intriguing hypothesis that the cyrtophorian oral 
apparatus is a secondary one based on the very 
divergent nature of these oral kinetids. Turning 
the traditional view of phylogeny within the Class 
 PHYLLOPHARYNGEA upside-down, they claim 
that suctorians represent the basal branch with 
 cyrtophorians and chonotrichs deriving “typical” 
cytostomes and body ciliature secondarily! Clearly, 
sampling of more phyllopharyngean genera fol-
lowed by gene sequencing will help to resolve how 
basal the suctorians really are. Molecular phylo-
genetic analyses of SSUrRNA gene sequences do 
not resolve the question as suctorians are the sister 
clade to a cyrtophorine-chonotrich clade (Li & 
Song, 2006a; Snoeyenbos-West et al., 2004). 
Chilodonella and Trithigmostoma have also 
been models in understanding the global param-
eters of pattern formation in ciliates (see Frankel, 
1989). Contractile vacuole pore positioning at cell 
division suggests that new pores are positioned, 
in a probabilistic manner, with reference to the 
developing oral apparatus and the margins of the cell
(Kaczanowska, 1974, 1981). Variability in the 
number of ventral kineties has been determined 
to arise in Trithigmostoma following cell division . 
This is primarily due to how many left-field 
kineties are separated by the fission furrow since 
kineties typically decrease in length towards the 
left margin of the cell (Fig. 10.1) (Radzikowski 
& Golembiewska-Skoczylas, 1999). At each cell 
division, the right-most “stomatogenetic” kinety 
releases an anterior fragment, which separates, 
moves to the right of this kinety, and elongates by 
replication. This at least compensates for the loss of 
one left-field kinety (Deroux, 1994a; Radzikowski 
& Golembiewska-Skoczylas, 1999). However, 
 “stomatogenic” kineties can vary in position, lead-
ing to a phenomenon similar to cortical slippage 
in the oligohymenophorean Tetrahymena (Frankel, 
1989; Radzikowski & Golembiewska-Skoczylas). 
This indicates that it is not the kinety per se that 
has the morphogenetic “potential” but rather some 
particular region of the cortex, specified in a proba-
bilistic manner by a global patterning mechanism , 
like that for contractile vacuole positioning (see 
Frankel, 1989). Parental cytopharyngeal structures 
typically dedifferentiate and redifferentiate in syn-
chrony with those of the opisthe. 
 Chonotrichs reproduce by two major kinds of 
 budding , termed exogemmous and cryptogemmous 
(Jankowski, 1973b, 1975). The swarmer is pro-
duced probably by continuity with the ciliature of 
the parent in exogemmous forms. Cryptogemmous 
forms develop within a crypt, which may derive its 
kinetosomes by migration from the parental field 
(Gunderson, 1984). One bud is typically formed 
Fig. 10.9. Merotelokinetal division morphogenesis of the cyrtophorian Chlamydonella pseudochilodon . Note how the 
new oral structures appear in the equatorial region by kinetosomal replication of a few somatic kineties ( a ). These 
kinetosomes assemble as oral dikinetids ( b ) and undergo a counter-clockwise rotation as seen from outside the cell 
(b–d ). (Redrawn from Deroux, 1970.)
followed by regrowth of the parent. However, 
sequential reactive budding can occur at times when 
the host molts or dies (Batisse, 1994a; Jankowski, 
1973b). Very few buds have been described from 
silver stained specimens. However, those that have 
been described remind one of a dysteriid-like cyr-
tophorian with a right ventral kinety field extend-
ing anteriorly over a smaller left ventral kinety field 
(Fig. 10.2). There is also an adhesive organelle in 
the posterior (see Dobrza ska-Kaczanowska, 1963; 
Fahrni, 1984; Guilcher, 1951; Jankowski, 1973b; 
Taylor, Lynn, & Gransden, 1995). 
 Rhynchodian cell division can be equal or unequal. 
Since there is no oral ciliature, it is an uncomplicated 
division of the somatic kineties. The parental cytopha-
ryngeal apparatus dedifferentiates and redifferentiates 
in synchrony with that of the opisthe (de Puytorac, 
1994b). Sphenophryids may have a division that is so 
unequal that it could be called budding (Chatton & 
Lwoff, 1950; Dobrza ska, 1961). 
 The suctorian bud or swarmer , like that of the 
 chonotrichs , is a short-lived dispersal stage. It may 
be ciliated or it may be worm-like and non-ciliated. 
The bud “recapitulates” the phylogenetic origin of 
the group, under the hypothesis that suctorians are 
a derived group (but see Kurth & Bardele, 2001 
and above). Budding can be simple or single or it 
can be multiple, either successive or simultaneous. 
 Reactive budding , as in the chonotrichs , may occur 
under unfavourable conditions or when the host 
molts, possibly stimulated by ecdysone (Batisse, 
1994b; Walker & Roberts, 1988). There are several 
schemes of classification for budding (Batisse; 
Collin, 1912; Corliss, 1979; Kormos & Kormos, 
1957a, 1957b). We follow Corliss (1979) until 
molecular evidence confirms the diversity sug-
gested by Batisse and Dovgal (2002). In exogenous 
budding , the bud infraciliature develops on the cell 
surface of the parent followed by an uncompli-
cated cell division, sometimes almost equal (e.g., 
Podophrya – Fauré-Fremiet, 1945). In evaginative 
budding , the bud infraciliature begins development 
in a pocket that erupts rapidly out of the parental 
cell surface (e.g., Discophrya – Henk & Paulin, 
1977). In endogenous budding , the bud devel-
ops and is completed within a brood pouch . The 
 swarmer then exits through a “ birth pore ” (e.g., 
Tokophrya – Noble, 1932) (Fig. 2.11cb–d). 
 There have been relatively few studies on the 
ultrastructural aspects of division morphogenesis 
in suctoria . Non-ciliated kinetosomes, often near 
the parental contractile vacuole pore, replicate 
to produce the infraciliature of the swarmer. The 
kinetal pattern of Discophrya is very reminiscent 
of a cyrtophorian with kineties curving around 
the “anterior” end (Fig. 10.5) (Canella, 1957; 
Plachter, 1979; Suárez, Guinea, & Fernández-
Galiano, 1987a). However, these kineties curve 
around the scopuloid NOT the oral region,