Protostomatida (Table 1) ingest food by

Description

;' infolding a large , unciliated surface, bounded by a single cell membrane (Small , 1984 ; Lenk, Small and Gunderson, 1984) (Figs . 39,40). We consider this process ancestral , due to the nuclear characters of these ciliates (Corliss , 1979; Raikov, 1969, 1982), their kinetid structure (Lynn and Small, 1 9 81 ) , and the sequence of their small subunit rRNA (Embley et al. 1995; Hammerschmidt et al., 1995) . Bridging this group and the next are species of the Trachelocercidae, which ingest food in a restricted apical area not surrounded by differentiated oral kinetids (Figs . 41 ,42) (2) Cytostomial phagotrophy and oral kinetids . The majority of ciliates can be placed in this group . Variations are described with reference to particular genera. Where possible, figures within this section are grouped to show taxonomic affinities . (a) Cytostome anterior, apical or subapical. . Some species of Trachelocercidae may have a permanent cytopharynx with perhaps differentiated oral kinetids around it (Figs . 41, 42) . They also have primitive nuclear dualism . The simplest oral region with surrounding differentiated oral kinetids occurs in the Subclass Haptoria (representative genera , Figs. 43-49). The cytostome is only as an apical or apicoventral, dome-shaped or 382 CILIOPHORA, INTRODUCTION PD CP CM ---+++--++-++-++1-- (1) (a) Ax P (1) ~ 0~ ~ 0~ 0-... 0 00-.._,_ (2) 00-... 0~ D. b PS (3) and at several levels ((1 )-(5)) in transverse section. patterns, sh The kinetid , an organeliar complex, has at least 5 unit (a,b): Monok organelles. The central or "organizing" kinetosome Is a (small circl tubul ar cylinder - 0.2 1-Jm In diameter and - 0.5 1-Jm In and, in some height. A proximal cartwheel Structure (CW) links the 9 dikinetid ki triplets together. Medially, dense material may Occupy ciliatlon of th e lumen of the kinetosome. Di stally, the kinetosome The latter a is occl uded by terminal plate (TP) and axosomal plate as found in (AxP); there , peripheral triplets lose the outer common In co microtubule to beome peripheral doublets of the ci li ary below, a fre axoneme (PO) (ct. (3) , (2)). Axosomal plate (AxP) Is nassophorean the proximal end of the cilium with its axonemal "9+2" pattern ofte fibril s. One of the central pair (CP) of mic rotubules hypotrich; ( arises in an ovoid dense body , the axosome (Ax). monokinetids Peripheral doublets (PO) are linked to the central pair (i) linear p (CP) by radial spokes (see (1 )) ; the cilium Is covered plagiopylids by the cell membrane (CM). Besid es the cilium, 3 other polykinetlds unit orga nell es are common (see (4)): a transverse tricha , and ribbon of microtubules (T) ; a postcill ary ribbon of polykinetids microtubules (Pc); and a Operiodicall y striated (m). klnetodesrnal fibril (Kd) . The membranous parasomal sac (PS) is a usual component of the kinetid. Viewed support the as if, from inside the organisms (from Lynn , 1981 ). cilia are us cilia and ap elongate region , usually not as a permanent cilia ("cour opening , but formed as prey is captured and occur in the ingested (Figs.43-48) . The cytopharynx , transverse m when present, is supported by transverse the Actinobo microtubules that originate from the oral Non-motile s kinetids , typically dikinetids , surrounding club-shaped the cytostome . Microtubular rods or near the cou nematodesmata (nematodesma , sing .) 48). These c also extend from these oral kinetosomes to appropriate 0~ 0 0 8\ o' \ ~ oC7-...... g_ 00 o 'o o-: 0 0" 0~ 0~ 0~ 00 0~ 0 ~ ~ 0~ ()... ~ 0~ o<;\ '00 oo 0 0--.,__ ~ oo 00-.._,_ 0 0~ o· 0 ~ 0~ oo..._ ~ Q.. 0~ ~' ~ G "-. :~ 0 ~ ~()... 00-.._,_ 00 G"""' 0 0-.._,_ G-..... ~ ~ G 0~ o0 o ~""" ~~ 0~ ~ 0~ 00 0-... oQ " 0~ 0~ C. d. e. f g. h. j. k. xamples of various somatic cortical own as viewed frorn outside the organisms. inetid kinetles . Note: parasomal sacs es) may be anterior or right of the cilium (a) suctorlans, on both sides (b) . (c-1 ): netles. Note: position of the parasomal sac; kinetosomes; and patterns of sliver li nes . re : (c) a common pattern among cilates ; (d} some hymenosromatian scuticocil lates ; (a) lpodeans ; (f) a prostomatean pattern ; (g) quent anterior or perioral pattern In some s and oligohymenopnoreans ; above , a n found In splrotrlchs ; (h) dorsal kinety of a I) oligohymenophorean klnety that combine s and dikinetids. (1-m) : Polykinetid kinetl es; olykinetids found in some metopids, , and scuticoi lates; (k) square-packed found In some microthoracids , hetero- hypotrichs; (I) hexagonally packed (cirri) in which ciliary length may be variabl e ingestatory process . The oral ually longer than adjacent somatic pear to form an anterior crown of onne ciliaire") . Toxicysts oral area, inserted between icrotubular ribbons (except in lin idae and pleurostomatids) . omatic cilia that appear swollen , or rod-like sometimes occur ronne ciliaire (Figs. 45 , 4 6 , lavate cilia apparently sense prey, perhaps by chemo CILIOPHORA, INTRODU Figs. 9-26. Scanning electron micrograph s of the cortex of various ciliate genera as evidence t o r the schematic patterns described and ill ustrat ed in Fig. 8. B. Fig. 9. Somatic co rt ex of Tetrahymena pyriformis wi th ciliated monokineti ds reception . Some ci liates in this group may have a perma nent cytostome and cytopharynx (Fig .49 ). Oral reg ion s in the Class Prostomatea are sligh tly more complex (Figs. 50 -58) . The cyto stome is us ually permanent and often app ears apical or subap ical (Fi gs. 52-58). Postci liary microtu bu les from oral dikinetids of th e couronn e cili aire may support both the cytopharyn x and a precytostomal CTION 38 3 depression . In add ition , nematodesmata aris ing from these oral kinetids prov ide addition structural support to the oral apparatus . Dikinetids or small polykinetids often occur near, but always posterior to the cytostome (Figs. 53 -58) ; this brosse ciliature may be tactile or chemosensory . Toxicysts , if present, are never in the cytostomal area and though typically somatic , may occur in special processes outside the oral area. The precytostomal dep ression is a more elaborately ciliated , deep funnel in the Subclass Trichostomatia of the Class Litostomatea (Table 1). The diagrams (Figs . 59-62) show how complex this vestibular cavity can become. The entodiniomorphids have complex oral apparatuses that include special ized depressions with oral polykinetids . The plag iopylid cil iates (Figs . 63 , 64) have oral cavi ti es that are structu rally simila r to those of the trichostomes ; however, Small and Lynn (1981) transferred them to the Subphylum Cyrtophora , Class Oligohymenophorea due to characters of their somatic kinetids . Here , we conclude that they belong to a separate class of ciliates . Their vestibula are also funn el-shaped depressions supported by densely packed ciliated kinetosomes (Figs . 63 , 64) . The relatively "simple" oral apparatus of members of the Subclass Haptoria of the Class Litostomatea demonstrates several structural similarities . In most, the cytostomal area is ringed by dikinetids of longer cilia (the couronne ci liaire) . Transverse microtubular ribbons (T) originate near oral dikinetids and extend to support the temporary or permanent cytopharynx (Figs . 65a , b ). Nematodesmata originate from th e base of one or both oral dikinetid kinetosomes , which are joined apically by a ring of filaments . Collectively, all these structures comprise the rhabdos (Corliss , 1979) . Toxicysts insert typ ically on the cytostome-directed transverse microtubules . (b) Cytostome ventra l, NEVER anterior. Ciliates thus grouped are scattered throughout the phylum . There is great variety of A, INTRODUCTION CILIOPHORA, INTRODUCTION cucullus. Fig 12 . Doub Paramecium micronucleat ciliated dikinetids of Somatic polykinetids or Euplotes eurostomus . c seemingly fused cilia . are not ciliated but ap 18-23. Fig . 18. Decili scuticociliate Pleuroco dikinetids and complex cortical membranes . Fi surface of the scuticoc curt us shows extent of surface patterning of t

Type species

Figures

Raw text

;' infolding a large , unciliated surface, bounded
by a single cell membrane (Small , 1984 ;
Lenk, Small and Gunderson, 1984) (Figs .
39,40). We consider this process ancestral ,
due to the nuclear characters of these ciliates
(Corliss , 1979; Raikov, 1969, 1982), their
kinetid structure (Lynn and Small, 1 9 81 ) ,
and the sequence of their small subunit rRNA
(Embley et al. 1995; Hammerschmidt et al.,
1995) . Bridging this group and the next are
species of the Trachelocercidae, which ingest
food in a restricted apical area not surrounded
by differentiated oral kinetids (Figs . 41 ,42)
(2) Cytostomial phagotrophy and oral
kinetids .
The majority of ciliates can be placed in this
group . Variations are described with
reference to particular genera. Where
possible, figures within this section are
grouped to show taxonomic affinities .
(a) Cytostome anterior, apical or subapical. .
Some species of Trachelocercidae may have a
permanent cytopharynx with perhaps
differentiated oral kinetids around it (Figs .
41, 42) . They also have primitive nuclear
dualism .
The simplest oral region with surrounding
differentiated oral kinetids occurs in the
Subclass Haptoria (representative genera ,
Figs. 43-49). The cytostome is only as an
apical or apicoventral, dome-shaped or
382 CILIOPHORA, INTRODUCTION
PD CP
CM
---+++--++-++-++1-- (1)
(a)
Ax P
(1)
~ 0~
~ 0~
0-... 0
00-.._,_
(2) 00-...
0~
D. b
PS
(3)
and at several levels ((1 )-(5)) in transverse section. patterns, sh
The kinetid , an organeliar complex, has at least 5 unit (a,b): Monok
organelles. The central or "organizing" kinetosome Is a (small circl
tubul ar cylinder - 0.2 1-Jm In diameter and - 0.5 1-Jm In and, in some
height. A proximal cartwheel Structure (CW) links the 9 dikinetid ki
triplets together. Medially, dense material may Occupy ciliatlon of
th e lumen of the kinetosome. Di stally, the kinetosome The latter a
is occl uded by terminal plate (TP) and axosomal plate as found in
(AxP); there , peripheral triplets lose the outer common In co
microtubule to beome peripheral doublets of the ci li ary below, a fre
axoneme (PO) (ct. (3) , (2)). Axosomal plate (AxP) Is nassophorean
the proximal end of the cilium with its axonemal "9+2" pattern ofte
fibril s. One of the central pair (CP) of mic rotubules hypotrich; (
arises in an ovoid dense body , the axosome (Ax). monokinetids
Peripheral doublets (PO) are linked to the central pair (i) linear p
(CP) by radial spokes (see (1 )) ; the cilium Is covered plagiopylids
by the cell membrane (CM). Besid es the cilium, 3 other polykinetlds
unit orga nell es are common (see (4)): a transverse tricha , and
ribbon of microtubules (T) ; a postcill ary ribbon of polykinetids
microtubules (Pc); and a Operiodicall y striated (m).
klnetodesrnal fibril (Kd) . The membranous parasomal
sac (PS) is a usual component of the kinetid. Viewed support the
as if, from inside the organisms (from Lynn , 1981 ).
cilia are us
cilia and ap
elongate region , usually not as a permanent
cilia ("cour
opening , but formed as prey is captured and
occur in the
ingested (Figs.43-48) . The cytopharynx ,
transverse m
when present, is supported by transverse
the Actinobo
microtubules that originate from the oral
Non-motile s
kinetids , typically dikinetids , surrounding
club-shaped
the cytostome . Microtubular rods or
near the cou
nematodesmata (nematodesma , sing .)
48). These c
also extend from these oral kinetosomes to
appropriate
0~ 0
0 8\
o' \ ~ oC7-...... g_
00 o 'o o-:
0 0"
0~ 0~
0~ 00 0~ 0
~ ~ 0~ ()...
~ 0~
o<;\ '00 oo
0 0--.,__
~ oo
00-.._,_ 0 0~ o· 0
~ 0~ oo..._ ~
Q..
0~
~'
~ G "-.
:~ 0 ~ ~()...
00-.._,_ 00 G"""' 0
0-.._,_ G-..... ~ ~
G
0~ o0 o
~"""
~~ 0~ ~
0~ 00
0-...
oQ "
0~
0~
C. d. e. f g. h. j. k.
xamples of various somatic cortical
own as viewed frorn outside the organisms.
inetid kinetles . Note: parasomal sacs
es) may be anterior or right of the cilium (a)
suctorlans, on both sides (b) . (c-1 ):
netles. Note: position of the parasomal sac;
kinetosomes; and patterns of sliver li nes .
re : (c) a common pattern among cilates ; (d}
some hymenosromatian scuticocil lates ; (a)
lpodeans ; (f) a prostomatean pattern ; (g)
quent anterior or perioral pattern In some
s and oligohymenopnoreans ; above , a
n found In splrotrlchs ; (h) dorsal kinety of a
I) oligohymenophorean klnety that combine s
and dikinetids. (1-m) : Polykinetid kinetl es;
olykinetids found in some metopids,
, and scuticoi lates; (k) square-packed
found In some microthoracids , hetero-
hypotrichs; (I) hexagonally packed
(cirri) in which ciliary length may be variabl e
ingestatory process . The oral
ually longer than adjacent somatic
pear to form an anterior crown of
onne ciliaire") . Toxicysts
oral area, inserted between
icrotubular ribbons (except in
lin idae and pleurostomatids) .
omatic cilia that appear swollen ,
or rod-like sometimes occur
ronne ciliaire (Figs. 45 , 4 6 ,
lavate cilia apparently sense
prey, perhaps by chemo
CILIOPHORA, INTRODU
Figs. 9-26. Scanning electron micrograph s of the
cortex of various ciliate genera as evidence t o r
the schematic patterns described and ill ustrat ed
in Fig. 8. B. Fig. 9. Somatic co rt ex of
Tetrahymena pyriformis wi th ciliated
monokineti ds
reception . Some ci liates in this group may
have a perma nent cytostome and cytopharynx
(Fig .49 ).
Oral reg ion s in the Class Prostomatea are
sligh tly more complex (Figs. 50 -58) . The
cyto stome is us ually permanent and often
app ears apical or subap ical (Fi gs. 52-58).
Postci liary microtu bu les from oral dikinetids
of th e couronn e cili aire may support both the
cytopharyn x and a precytostomal
CTION 38 3
depression . In add ition , nematodesmata
aris ing from these oral kinetids prov ide
addition structural support to the oral
apparatus . Dikinetids or small polykinetids
often occur near, but always posterior to the
cytostome (Figs. 53 -58) ; this brosse
ciliature may be tactile or chemosensory .
Toxicysts , if present, are never in the
cytostomal area and though typically somatic ,
may occur in special processes outside the
oral area. The precytostomal dep ression is a
more elaborately ciliated , deep funnel in the
Subclass Trichostomatia of the Class
Litostomatea (Table 1). The diagrams (Figs .
59-62) show how complex this vestibular
cavity can become. The entodiniomorphids
have complex oral apparatuses that include
special ized depressions with oral
polykinetids . The plag iopylid cil iates (Figs .
63 , 64) have oral cavi ti es that are
structu rally simila r to those of the
trichostomes ; however, Small and Lynn
(1981) transferred them to the Subphylum
Cyrtophora , Class Oligohymenophorea due to
characters of their somatic kinetids . Here ,
we conclude that they belong to a separate
class of ciliates . Their vestibula are also
funn el-shaped depressions supported by
densely packed ciliated kinetosomes (Figs .
63 , 64) .
The relatively "simple" oral apparatus of
members of the Subclass Haptoria of the Class
Litostomatea demonstrates several structural
similarities . In most, the cytostomal area is
ringed by dikinetids of longer cilia (the
couronne ci liaire) . Transverse microtubular
ribbons (T) originate near oral dikinetids and
extend to support the temporary or
permanent cytopharynx (Figs . 65a , b ).
Nematodesmata originate from th e base of one
or both oral dikinetid kinetosomes , which are
joined apically by a ring of filaments .
Collectively, all these structures comprise
the rhabdos (Corliss , 1979) . Toxicysts
insert typ ically on the cytostome-directed
transverse microtubules .
(b) Cytostome ventra l, NEVER anterior.
Ciliates thus grouped are scattered throughout
the phylum . There is great variety of
A, INTRODUCTION
CILIOPHORA, INTRODUCTION
cucullus. Fig 12 . Doub
Paramecium micronucleat
ciliated dikinetids of
Somatic polykinetids or
Euplotes eurostomus . c
seemingly fused cilia .
are not ciliated but ap
18-23. Fig . 18. Decili
scuticociliate Pleuroco
dikinetids and complex
cortical membranes . Fi
surface of the scuticoc
curt us shows extent of
surface patterning of t