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there is no consensus 
on subdivision within the subclass. Batisse (1975) 
described seven suborders within what was then the 
Order Suctorida . He has now supported three orders 
with eight included suborders in a Subclass Suctoria 
(Batisse, 1994b). These systems are modeled on 
Fig. 10.2. Stylized drawings of representatives of the Subclass Chonotrichia of the Class PHYLLOPHARYNGEA .
The exogemmid Chilodochona . The exogemmid Spirochona and its bud . Note the similarity of the bud’s ciliary pat-
tern to the cyrtophorians . The cryptogemmids Chonosaurus , Armichona , and Spinichona
10.1 Taxonomic Structure 213
Fig. 10.3. Stylized drawings of representatives of the Subclasses Rhynchodia and Suctoria of the Class 
 PHYLLOPHARYNGEA . Members of the Subclass Rhynchodia . The hypocomatid Hypocoma . The rhynchodids
Raabella and Ancistrocoma . Members of the Subclass Suctoria . The highly unusual endoparasite of guinea pigs , the 
 evaginogenid Cyathodinium . This ciliated suctorian has its tentacles reduced to small protuberances along the left 
border of a cortical depression. The bud of the endogenid Enchelyomorpha , exhibiting a rare condition in which the 
 bud bears tentacles
the morphogenetic analyses of Kormos and Kormos 
(1957a, 1957b, 1958). Jankowski (1980) listed five 
subclasses and 21 orders in a Class Suctoria . We 
conservatively follow Lynn and Small (2002) and 
Matthes et al. (1988) in recognizing three orders 
based on modes of asexual reproduction (Figs. 
2.11cb–d, 10.3–10.6). The Orders Exogenida and 
 Endogenida were suggested by Collin (1912) 
Fig. 10.4. Stylized drawings of representatives of the Subclass Suctoria of the Class PHYLLOPHARYNGEA .
The endogenid Acineta and its bud . The exogenid Asterifer . The evaginogenid Dendrocometes and its bud 
10.1 Taxonomic Structure 215
while the Order Evaginogenida was suggested by 
Jankowski (1975). Monographic works by Dovgal 
(1996, 2002) support these three taxa. However, 
Dovgal (2002) recognized the suctorians as a class 
and adds a fourth taxon, the Subclass Vermigenia 
Jankowski, 1978, to include suctorians whose 
swarmers are vermiform and non-ciliated. While 
this is truly an unusual kind of budding , we still 
consider it a type of exogenous budding , and will 
await the demonstration by gene sequencing that 
these taxa are sufficiently divergent and mono-
phyletic to be recognized at this taxonomic level. 
Nevertheless, we have relied particularly heavily on 
Dovgal (2002) whose numerical phenetic analysis 
has provided the most objective assessment of char-
acter state distributions among suctorians . 
 The exogenids reproduce by budding with 
cytokinesis occurring on the cortical surface of 
the parental cell. This order includes 17 fami-
lies: Allantosomatidae , Dentacinetidae , Dendro-
somididae , Ephelotidae , Manuelophryidae , 
 Metacinetidae , Ophryodendridae , Paracinetidae , 
 Phalacrocleptidae , Podophryidae , Praethecaci-
netidae , Rhabdophryidae , Severonidae , Spelaeo-
phryidae , Stylostomatidae , Tachyblastonidae , and 
 Thecacinetidae . The Family Phalacrocleptidae , 
monotypic for the genus Phalacrocleptes , is the 
exceptional ciliate – kinetosomes have never been 
observed. However, it does have a macronucleus 
and micronuclues, and with short tentacles enclos-
ing one haptocyst in each, its suctorian affini-
ties are certain (Kozloff, 1966; Lom & Kozloff, 
1967). Budding and cytokinesis in the endog-
enids occurs in a brood pouch with the swarmer
typically exiting through a “ birth pore .” Thirteen 
families are placed in this order: Acinetidae , 
 Acinetopsidae , Choanophryidae , Corynophryidae , 
 Dactylostomatidae , Dendrosomatidae , Endos-
phaeridae , Erastophryidae , Pseudogemmidae , 
 Rhynchetidae , Solenophryidae , Tokophryidae , and
 Trichophryidae . The Order Evaginogenida includes 
suctorians in which the kinetosomes of larval 
kineties first replicate on the “parental” surface 
of the brood pouch while cytokinesis is com-
pleted externally or exogenously. Eleven families 
are assigned to this order: the Cometodendridae , 
 Cyathodiniidae , Dendrocometidae , Discophryidae , 
 Enchelyomorphidae , Heliophryidae , Periacinet-
idae , Prodiscophryidae , Rhynchophryidae , 
 Stylocometidae , and Trypanococcidae . The 
Family Enchelyomorphidae includes the genus 
Enchelyomorpha , long-considered a tentacled, 
 actinobolinid gymnostome (Corliss, 1961, 1979), 
but now known to be the swarmer of a globular 
 suctorian (Foissner & Foissner, 1995) (Fig. 10.3). 
The Family Cyathodiniidae includes the genus 
Cyathodinium , an endosymbiont of the caecum of 
the guinea pig Cavia porcella . Its suctorian affinities
were demonstrated by Paulin and Corliss (1964, 
1969) who revealed the tentacle-like substructure 
of its endosprits and the presence of haptocysts 
(Fig. 10.3). 
 10.2 Life History and Ecology 
 Members of the Class PHYLLOPHARYNGEA 
can be divided into those that are free-living and 
those that are symbiotic, either commensal or 
parasitic but never mutualistic. The full range 
of these free-living and symbiotic life histories 
can be found among members of the subclasses 
 Cyrtophoria and Suctoria while members of the 
subclasses Rhynchodia and Chonotrichia are 
obligate symbionts. Rhynchodians are obligate 
predators or parasites and chonotrichs are obli-
gate commensals. Suctorians and chonotrichs 
have convergently evolved dimorphic life his-
tories: a sessile trophont divides to produce a 
motile dispersal swarmer . Distributions of the 
free-living members of the class are very likely 
global while the distributions of the symbionts, 
as with symbiotic forms from other classes, are 
likely limited by the distributions of their 
preferred hosts. 
 Members of the Subclass Cyrtophoria , such 
as Chilodonella , Dysteria , and others, have been 
found around the world: in terrestrial habitats, 
likes soils and mosses from Europe (Foissner, 
1979a, 1988b; Grolière, 1977), Africa (Buitkamp, 
1977), Asia (Wang, 1977), and Antarctica (Petz 
& Foissner, 1997); in freshwater streams (Cleven, 
2004) and ponds in Europe (Grolière, 1977; 
Madoni & Sartore, 2003), Africa (Dragesco, 
1965; Dragesco & Dragesco-Kernéïs, 1986), and 
 North America and Mexico (López-Ochoterena, 
1966); and in marine habitats, such as sublittoral 
sediments from Europe (Deroux, 1976a, 1976b; 
Deroux & Dragesco, 1968; Dragesco, 1963) and 
 North America (Borror, 1963), on kelps and other 
marine vegetation in Europe (Gismervik, 2004); in 
deep benthic Mediterranean sediments (Hausmann, 
Hülsmann, Polianski, Schade, & Weitere, 2002), 
and in sea ice in Antarctica (Garrison et al., 2005). 
Their flattened body form is particularly adapted 
for benthic or interstitial habitats, although some 
species of Pseudochilodonopsis (Foissner, 1988b) 
and Gymnozoum (formerly Spiroprorodon ) (Corliss 
& Snyder, 1986) can be found in the plankton. 
 Cyrtophorians are typically found in the bio-
films on substrates where they use the tooth-like 
 capitula on the cytopharyngeal apparatus to browse 
on bacteria , diatoms , filamentous green algae , and 
 cyanobacteria (Deroux, 1994a; Foissner, 1988b). 
This preference for biofilms probably leads them 
to exploit these films on the body surfaces of 
invertebrates, such as crustaceans , where they can 
be facultative (i.e., Chilodonella spp.) or obli-
gate (i.e., Allosphaerium ) symbionts (Dobrza ska-
Kaczanowska, 1963; Morado & Small, 1995). 
They do not likely present disease problems in 
 crustaceans . However, two species, Chilodonella
cyprini and Chilodonella hexasticha , do cause 
disease of freshwater and marine fishes (Hoffman,