- Email: [email protected]
Redescriptions of three marine ciliates, Strombidium elegans Florentin, 1901, Strombidium sulcatum Claparède & Lachmann, 1859 and Heterostrombidium paracalkinsi Lei, Xu & Song, 1999 (Ciliophora, Oligotrichida)
Europ. J. Protisto!. 36, 327-342 (2000) September 25,2000 http://www.urbanfischer.de/journals/ejp
European Journal of
PROTISTOLOGY
Redescriptions of Three Marine Ciliates, Strombidium elegans Florentin, 1901, Strombidium sulcatum Claparede & Lachmann, 1859 and Heterostrombidium paracalkinsi Lei, Xu & Song, 1999 (Ciliophora, Oligotrichida) Weibo Sonq'>, Mei Wang 1 and Alan warren1
2
Laboratory of Protozoology, ARL, Ocean University of Qingdao, 266003 Qingdao, P.R. China Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
Summary The morphology and infraciliature of three marine oligotrich ciliates, Strombidium elegans Florentin, 1901, Strombidium sulcatum Claparede & Lachmann, 1859, and Heterostrombidium paracalkinsi Lei, Xu & Song, 1999, collected from coastal mollusc farming ponds near Qingdao (Yellow Sea, north China) are investigated based on observations of specimens in vivo and following protargol impregnation. Since no recent data deriving from modern studies on Strombidium elegans are available, a detailed redescription is given and some synonyms are suggested. As a commonly occurring form, further morphological and morphometrical data on S. sulcatum are supplied based on four populations from the Qingdao region. Other populations of Strombidium sulcatum reported previously in the literature are compared with our organisms and the taxonomic status of each is discussed. The genus Heterostrombidium Song, 1999 is a recently erected taxon characterised by the presence of a few dorsal attaching membranelles that are connected with "normal" collar membranelles on dorsal side. The relationship between H. paracalkinsi and H. calkinsi (Faure-Fremiet, 1932) Song, 1999 is discussed. Following a review of the data provided by previous investigators, four other taxa are synonymized thus; Strombidium sauerbreyae (Sauerbrey, 1928) sensu Faure-Frerniet, 1950 and S. armatum Burger, 1908 [synonyms of S. elegans]; Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 and S. lagenula Faure-Frerniet, 1924 [synonyms of S. sulcatum]. Additional notes on Heterostrombidium paracalkinsi Lei, Xu and Song, 1999, are also provided. "corresponding author: Dr. Weibo Song, College of Fisheries, Ocean University of Qingdao, Qingdao 266003, P. R. China; Fax: ++86 532 2032283,E-mail: [email protected] © 2000 by Urban & Fischer Verlag
Key words: Marine ciliates; Oligotrichina; Morphology and infraciliature; New species; Yellow Sea, China.
Introduction Oligotrichs are often the dominant planktonic ciliates in both marine and freshwaters. About 200 putative aloricate species belonging to the suborder Oligotrichina have been reported [1, 11, 23, 29, 34, 39, 43, 49]. Since most of these organisms are small, fragile and highly motile, over two thirds of them have been only superficially described, in most cases these descriptions being based only on live specimens or on material fixed using classical methods [7, 8, 10, 15,24]. Only approximately one third have been studied with the help of the protargol impregnation technique [3, 12,22,30,35-37, 40]. Consequently, many ambiguities concerning the identification of taxa within this species-rich group have accumulated and previously reported species are frequently misidentified or overlooked in ecological and taxonomic studies. This is mainly because certain diagnostic features (viz. behaviour or movement, extrusomes, body shape, cell colour etc.) can, in most cases, only be seen in living cells while others such as ciliary patterns and buccal structures can only be discerned in silver-impregnated cells or by electron microscopy, both of which require fixation. Thus, modern techniques, in which cells are observed in vivo as well as following silver impregnation, are regarded as essential for adequate species descriptions. Furthermore, careful comparisons with those forms reported in the 0932-4739/00/36/03-327 $ 15.00/0
328
W. Song, M. Wang and A. Warren
older literature must also be carried out, especially when erecting new taxa. Taxonomic studies of planktonic ciliates in coastal waters near Qingdao, north China have been carried out for over a decade and many populations/species of aloricate oligotrichs have been isolated and observed. Many of those isolated have never been studied using modern techniques, including several previously known forms. In this paper, the morphology of one commonly occurring, "well known" species and two poorly known species are described. The taxonomic status of several closely related taxa is also discussed.
Material and Methods
Sampling sites and ecological features Seawater samples were collected from open ponds used for mollusc mariculture in the Yellow Sea coastal regions near Qingdao, Shandong Province, China. Both field material and raw cultures, which were kept for several days or weeks in the laboratory, were used for morphological studies. Ecological characteristics for all sampling sites were similar: generally oligo- to mesosaprobic coastal waters, salinity 30-32%0, pH ca. 8.0-8.3, water temperature ranged from 5-24 dc. Two populations of Strombidium elegans Florentin, 1901 were isolated from coastal waters off Qingdao (Tsingtao), China (january 10,1995 and April 16, 1996). Four populations of Strombidium sulcatum Claparede & Lachmann, 1859 were isolated during the year 1995 (17 April, 18 July, 14 October and 11 November) from coastal waters off Qingdao and from neighbouring areas. They were found to occur in large number. H eterostrombidium paracalkinsi Lei, Xu & Song, 1999 was isolated once in low number from samples collected from the coastal waters near Qingdao (20 June, 1996).
Observations, staining and terminology In order to observe locomotion, all organisms were kept in Petri dishes with the water in which they were growing. They were observed first under a stereomicroscope (x64 magnification), and were then transferred onto microscope slides (without cover glasses) and observed at low magnifications (xl 00-200) under a compound microscope. All species were observed in vivo with phase contrast and differential interference contrast microscopy. The infraciliature was revealed by protargol impregnation [48]. Counts, drawings and measurements were performed at a magnification of x1250. Terminology is mainly according to Corliss [9], Lynn and Montagnes [31] and Krainer [25]. A few terms that might be confusing are explained in the following paragraphs. Buccal membranelles: (= ventral polykinetids) membranelles which are clearly separated from the collar membranelles and located along the buccal cavity. Circle kinety: (= girdle kinety or equatorial kinety) a single row of dikinetids which encircles the equatorial region of the cell.
Collar membranelles: (= anterior polykinetids) membranelles which occupy the collar region and encircle the apical protrusion. Extrusome girdle: (= circumferential girdle) belt-like structure on the surface of cell, usually around the equatorial region anterior to the circle kinety, which demonstrates the outer ends of extrusomes. In vivo it often consists of longitudinally arranged, granule-like, rough protrusions, while after protargol impregnation it appears as an independent girdle, containing densely arranged argyrophilic fibres or meshes. Perilemma: the outermost structure of the cell covering the whole pellicle, but most conspicuous around the posterior half of the cell and beneath which the polygonal cortical platelets are distributed. Ventral kinety: the short, postequatorial kinety, longitudinally oriented on ventral side (with exception) and usually located in the caudal region. Prolonged membranelles: belong to the collar membranelles but having considerably longer bases and cilia, and are usually used for attaching to a substrate.
Slide depositions Voucher slides of protargol-impregnated specimens of Strombidium elegans are deposited in the Natural History Museum, London with the following registration number: Strombidium elegans; 2000:01:01:01 and 2000:01:01:02. For Heterostrombidium paracalkinsi, one paratype slide is deposited in the NHM with registration number; 2000: 01:01:03 (the holotype is deposited in the Laboratory of Protozoology, College of Fisheries, Ocean University of Qingdao, P. R. China).
Results Family Strombidiidae Faure-Fremiet, 1969 Genus Strombidium Claparede & Lachmann, 1859
Strombidium elegans Florentin, 1901 (Fig. 1-9, 39-42; Table 1) Syn. S. armatum Burger, 1908 S. sauerbreyae sensu Faure-Fremiet, 1950 Spirostrombidium elegans (Florentin, 1901) Petz, Song & Wilbert, 1995 To the authors' knowledge, this species has never been investigated using modern methods, so we here supply a redescription based on an examination of the present populations. Improved diagnosis. Medium-sized, marine Strombidium 30-50x20-30 pm in vivo with somewhat asymmetric, slim-cordate outline when viewed dorsa-ventrally and with pointed posterior end; 12-15 collar and 8-10 buccal membranelles; 2 posteriorly-directed prolonged membranelles; one macronucleus and one micronucleus; extrusomes prominent, ca. 7-10 pm long, arranged along cell margins; circle kinety consisting of 30-44 dikinetids, open on ventral side with both arms
Three Marine Oligotrichous Ciliates from China
329
Table 1. Morphometric characterization of Strombidium elegans-population I (line 1) and population II (line 2). Data based on protargol-impregnated specimens. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in pm
31 27
51 47
36.3 38.8
3.59 4.3
0.90 1.01
9.9 11.1
16 18
Body width in urn
16 18
27 26
20.1 21.2
2.13 3.7
0.54 0.87
10.6 17.5
16 18
12
21
14.7
1.66
0.42
11.3
16
No. of collar membranelles'"
12 13
14 15
12.9 13.9
0.83 0.7
0.22 0.2
6.4 5.1
14 19
No. of buccal membranelles
8 9
10 10
9.1 9.2
0.74 0.4
0.23 0.1
8.1 4.5
10 19
No. of basal body pairs in girdle kinety
30 37
39 44
34.1 40.5
3.18 2.3
0.88 0.6
9.3 5.7
13 17
No. of basal body pairs in ventral kinety
11 9
21 11
13.5 10.4
3.55 0.7
0.98 0.2
23.0 6.7
13 19
No. of macronucleus-segments
0 0
0 0
0 0
11 18
No. of micronuclei
0 0
0 0
0 0
9 18
~istance III
from apex to cytostome'
pm
Length of macronucleus in pm
11 18
18 28
13.9 24.4
2.22 2.9
0.56 0.7
16.0 11.7
16 16
10
18
14.9
2.2
0.5
14.6
16
Width of macronucleus in pm ':. Measured from anteriormost to the posterior end of buccal zone of membranelles; ':"'Including the prolonged membranelles.
shifted caudally; about 9-21 dikinetids in ventral kinety which is twisted towards the left. Redescription. Cell size in vivo mostly about 35-45 )lm in length. Body shape asymmetric, elongate cordate or obconical often with caudal part slightly twisted to right (Fig. 1); when viewed from ventral aspect, broadest part of cell always at "shoulder" area with caudal end more or less pointed; length to width ratio about 3:2 depending on stage in life cycle (Fig. 1, 5, 6). Dorsoventrally about 2:3 flattened (Fig. 4). Prominent apical protrusion (collar) distinct in vivo, but may disappear or be undetectable after fixation (Fig. 5-9). Buccal cavity deep, extending to about 1/3-2/5 of cell length (Fig. 1, 5, 6). Cilia of most membranelles about 20 )lm long, extending anteriorly as shown in Figures 1 and 3; cilia of two prolonged membranelles 30-50 )lm in length (depending on cell size), and always directed posteriorly like two tails (Fig. 1). Cells not very fragile, pellicle rather delicate with thin perilemma covering most of cell, but with no rec-
ognizable polygonal cortical platelets (Fig. 1). No distinct girdle present. Cytoplasm colourless to greyish, sometimes yellow-green due to ingested diatoms (Fig. 1, 4). Cell often containing several small globular lipid-like inclusions, 2-4 )lm across (Fig. 1). Food vacuoles few in number, frequently replete with very large diatoms (Fig. 39,41). Extrusomes prominent, about 10 )lm long, usually evenly spaced around periphery of the whole cell with exception of anteriormost region when viewed from ventral side (Fig. 1,5); in some small cells, probably following cell division, extrusomes sparsely arranged (Fig. 6). Contractile vacuole not found. Single macronucleus, ovoid to ellipsoidal, containing several large globular nucleoli (Fig. 5-7); single ovoid micronucleus about 2 )lm long, attached to macronucleus (Fig. 7). Locomotion with two main patterns: very fast and irregular when swimming (Fig. 2), or slow and even motionless for long periods when crawling over surfaces, using its 2 prolonged membranelles for attachment with ventral side down (Fig. 3).
330
W Song, M. Wang and A. Warren
J~ 2
1 3
!-
.." k
- CK
-
,.-
I
~~
\.,.--/
8
- -. / •
," \.......
"
I~
9
Fig. 1-9. Strombidium elegans from life (1-6) and after protargol impregnation (7-9). 1. Typical individual, ventral view. 2. Pattern of locomotion. 3. To show the creeping state, note the cell attached to the substrate with its two prolonged rnernbranelles, 4. Lateral view. 5, 6. To demonstrate the different body shapes. 7. Ventral view of ciliary pattern, arrow indicating the left arm of circle kinety; note that the ventral kinety is located in the right margin of cell. 8, 9. Ventral and dorsal view, to show some "extra" kinety fragments extrusornes (arrows); note that the "extra" kinety fragment extends over dorsal side. BAM - buccal membranelles, CAM - collar mernbranelles, CK - circle kinety, Co - collar, ExK - extra kinety, Ma - macronucleus, Mi - micronucleus, Pe - perilernma, Pm - prolonged membranelles, PM - par oral membrane, VK - ventral kinety. Scale bars in 1, 4-6 =25 pm; in 8, 9 =15 urn.
Somatic ciliature rather variable, basically consisting of one circle and one ventral kinety. Circle kinety shifted strongly posteriad on ventral side with both arms often slightly overlapping and forming a small gap through which ventral kinety inserts (Fig. 7-9). The Iat-
rer is usually long, extending to about 1/3 of body length and situated in shallow groove, distinctly shifted to right margin of cell (Fig. 7, 8). Some specimens (fewer than 1/3 of total individuals observed) possessing a fragment-like "extra" kinety, which is positioned
Three Marine Oligotrichous Ciliates from China
around "shoulder" area of cell and is composed of up to 15 or more sparsely arranged basal body pairs (Fig. 8,9, 42). In most cases, the extra kinety is very short and located either ventrally, posterior to buccal field, or on dorsal side, directly posterior to collar membranelles (Fig. 40). Extrusome girdle not observed. Buccal apparatus as shown in Figures 7 and 8. Buccal membranelles continuous with collar membranelles, invaginated into buccal cavity (Fig. 7). Bases of two prolonged collar membranelles about 12-15 pm in length (about twice as long as the other membranelles), positioned between collar and buccal membranelles (Fig. 7, 39). Paroral membrane on right wall of buccal cavity, extending to centre of apical protrusion; pharyngeal fibres about 7-20 pm long (Fig. 7, 8). Remarks and comparison with related species. In 1995, Petz, Song & Wilbert - without knowledge of its infraciliature - transferred this species into the genus Spirostrombidium, which is characterised thus: " ... equatorial kinety long and spiralling, viz. transversely encircling almost completely ventral and dorsal side and extending in wide spiral almost to or across posterior pole ... " [40]. According to the present study, the circle kinety of this species is neither spiral nor open but only highly "shifted" to the posterior area on ventral side. This species is therefore returned to the genus Strombidium. Our populations correspond well with Florentin's original description with reference to the basic morphology (the asymmetric body shape, size, etc.) and habitat [21]. Florentin [21], however, observed two contractile vacuoles in his organism. whereas no contractile vacuoles were observed in our population. We surmise that this character is either salinity-dependent or was misinterpreted by Florentin. In Florentin's drawing [21], the cell is depicted as possessing several prolonged membranelles among the collar mernbranelles rather than just two. Since this phenomenon was also observed by us in some newly divided cells, we assume that it represents a morphological variation. Finally, although Florentin [21] depicted the extrusomes as being present only on the dorsal side of the cell rather than around the periphery of the whole cell, we noted the arrangement of extrusomes varied somewhat according to the stage of the life cycle. The infraciliature of Strombidium armatum Burger, 1908 is still unknown. Based on the cell size, the general morphological appearance, distribution of extrusomes and the slightly prolonged membranelles, we surmise that it might be synonymized with the S. elegans. In 1950, Faure-Fremiet [17] described a form under the name "S. sauerbreyae Kahl" [24], despite the fact that its morphology is quite unlike that of the original [41]. Rather, it bears a strong resemblance to S. elegans, so it is here considered conspecific with the latter.
331
To date, approximately ten species of Strombidium with flattened body shape inhabiting marine biotopes have been reported [5, 6, 17,24,29,41,45-47]. However, few of these have been described using modern methods and this yields further confusion in terms of species separation and identification. The key morphological features of each of these taxa are given in Table 2. With reference to the morphologically related species (Table 2), Spirostrombidium cinctum (Kahl, 1932) Petz, Song & Wilbert, 1995 seems to be most similar to S. elegans. Although its infraciliature has not been described, S. cinctum can be distinguished by the distribution of extrusomes which are arranged around the entire cell margin (vs. absent from anteriormost region of cell in S. elegans), the deeply extended buccal field (ca. 1/2 vs. ca. 113 in S. elegans) and the absence of the prolonged membranelles (vs. present in S. elegans). Strombidium clavellinae Buddenbrock, 1922 is also very similar to S. elegans in terms of its general appearance [5]. It differs, however, in having four prolonged membranelles (vs. 2 in S. elegans), a rotund body shape (vs. elongate in S. elegans), and a much higher number of membranelles (total of buccal and collar membranelles 32-35 vs. 20-24 in S. elegans). The slender species, S. schizonstomum Kahl, 1932, the infraciliature of which is also unknown, exhibits a very different body shape (cylindrical), a conspicuously depressed girdle region in equatorial area, and possibly absence of the prolonged collar membranelles, all of which are in contrast to S. elegans. In 1932, Kahl reported a new species, Strombidium latum, which is characterized by its large size (100-140 pm long), many buccal membranelles, flat and wide oval body shape, and with extrusomes distributed throughout the cell [24]. Subsequently, Faure-Frerniet described a "population" of this taxon which he misidentified and very likely represents a separate, valid species [17]. Faure-Fremiet's isolate is characterized by its deeply extended buccal field (ca. 2/3 of body length), presence of 2 prolonged membranelles (vs. absent in S. latum) and with numerous buccal and collar rnembranelles (> 35). Strombidium elegans differs from the two organisms mentioned above, mainly in terms of body size (30-50 pm in S. elegans vs. > 100 urn) and in having fewer membranelles (8-10 in S. elegans vs. "numerous" as depicted by Kahl [24] and Faure-Frerniet [17]) (Table 2). Comparisons should also be made with two morphologically similar Spirostrombidium species: S. platum Song & Packroff, 1997 and S. echini Song, Wilbert & Warren, 1999. The latter is an endocommensal form inhabiting in digestive tract of sea urchins. It possesses an open circle kinety, the posterior end of which is divided into two parts giving the impression that this species has 2 ventral kineties [46], while the former is
Kahl, 1932
Data resource
Kahl, 1932
mesosaprobic (marine)
girdle groove conspICUOUS manne
Wang, 1934
manne sand Kahl, 1932
extrusomes all through cell margin
,,- Assumed from the illustrations; ,,-,,- Ventral kinety (VK) divided into 2 parts; ? Data unavailable or structure difficult to judge (or doubtful if present)
marine & brackish water
Habitats/biotopes or lifestyle (free-living if not otherwise specified)
Other features
1999
& Song,
Lei,Xu
manne
circle kinety open
87-121
-
-
-
present (3)
absent
13-16
ca. 12"-
absent
Number of dikinetids in circle kinety
absent?
absent?
Prolonged buccal adoral membranelles
ca. 2/3
ca. 1/3
ca. 1/3
absent
FaureFremiet, 1950
manne
original
mesosaprobic (marine)
body disgirdle symmetric groove conspICUOUS
37-44
present (2)
present (2)
endocommensal (marine)
Song, Wilbert & Warren, 1999
Buddenbrock, 1922
with "2" ventral kineties ,,-,,manne
-
>70
absent
19-24
ca. 25"-
12-15
present (4)
15-18
15-18
ca. 10"-
8-10
Song & Packroff, 1997
mesosaprobic (marine)
no ventral kinety
8-11
ca. 1/3
<1/4
1/4-1/3
conical
70-100
113-1/2
conical to ovoid
50-70
No. 10
widely oval
70-80
30-50
No.9
slimconic
No.8
No.7
ca.Ifi"
>20"-
widely oval
110-170
No.6
widely oval
20-22
>20"-
ca. 15'f
>15"-
No. of collar membranelles
70-80
36-55 cordate
No.5
No.4
ca. 20"-
>15"-
ca. 15"-
ca. 15"-
Length of buccal field: body length
No. of buccal adoral membranelles
cordate
Body shape ca. 2/5
100 -140
ca. 2/5
50-70
No.3
ca. 1/2
40-50
No.2
pot-like
(in vivo)
No.1
elongated
m]lm
C~lliength
Characters
Strombidium schizostomum Kahl, 1932 (No.2); Strombidium latum Kahl, 1932 (No.3); Strombidium pseudocinetum Wang, 1934 (No.4); Spirostrombidium urceolare (Stein in Faure-Frerniet, 1932) Lei et ai, 1999 (No.5); Strombidium latum sensu Faure-Frerniet, 1950 (No.6); Strombidium elegans Florentin, 1901 (No.7); Strombidium clavellinae Buddenbrock, 1922 (No.8); Spirostrombidium echini Song, Wilbert & Warren, 1999 (No.9) and Spirostrombidium platum Song & Packroff, 1997(No.10).
Table 2. Morphometric comparison of some marine, elegans-similar species with flattened body shape. Measurements in ]lm. Strombidium cinctum Kahl, 1932 (No.1);
w
::::J
;:0
;J> ~ (l) ....,
o,
::::J
(l)
1O
~ ::::J
'P :5:
::::J
0
VI
:::E
N
W
Three Marine Oligotrichous Ciliates from China
large (70-100 pm in length) and lacks a ventral kinety [45]. Based on these characters, both are clearly separated from S. elegans. Three morphological similar species from the genus Spirostrombidium, S. pseudocinctum (Wang, 1934) Petz, Song & Wilbert, 1995, S. oblongum (Entz, 1884) Petz, Song & Wilbert, 1995, and S. sauerbreyae (Sauerbrey, 1928) Petz, Song & Wilbert, 1995, can easily be distinguished from S. elegans on the basis of body shape, arrangement of extrusomes and general appearance of buccal membranelles [13,24,41,47]. Strombidium urceolare Stein in Faure-Fremiet, 1932 was re-identified only very recently [16, 28] and has been transferred to the genus Spirostrombidium as Spirostrombidium urceolare (Stein in Faure-Fremiet, 1932) Lei, Xu & Song, 1999. It differs from S. elegans in several respects, e.g. the number of attachment or-
333
ganelles (3 vs. 2), the ciliary pattern (girdle kinety open vs. girdle kinety closed and inserted by ventral kinety), the larger cell size (70-80 vs. 30-50 pm), and the number of buccal membranelles (13-16 vs. 8-10), collar membranelles (20-22 vs. 12-15) and dikinetids in the circle kinety (87-121 vs. 37-44) (Table 2).
Strombidium sulcatum Claparede & Lachmann, 1859 (Fig. 10-19,32-38; Table 3) Syn. Strombidium lagenula Faure-Frerniet, 1924 (?) Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 This supposedly well-known species has a cosmopolitan distribution and has been found in most kinds of marine biotope. For over 100 years, it has been re-
Table 3. Morphometric characterization of 4 populations of Strombidium sulcatum. Data from the authors and based on protargol impregnated specimens. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in urn
30 38 36 34
47 46 44 47
37.3 41.0 39.6 37.4
5.05 2.48 2.91 3.26
1.40 0.66 0.88 0.82
13.6 6.1 7.3 8.7
13 14 13 16
Body width in ).1m
24 26 32 25
34 33 41 33
28.0 29.2 37.2 27.8
3.11 2.05 2.49 2.37
0.86 0.55 0.69 0.59
11.1 3.4 6.7 8.5
13 14 13 16
No. of collar membranelles
13 14 14 14
15 15 16 15
13.7 14.2 14.6
0.71 0.60 0.77
0.24 0.17 0.22
5.2 4.2 5.3
9 13 13 4
No. of buccal membranelles
7 8 7 8
9 9 9 9
8.1
0.78
0.26
9.6
8.4
0.65
0.18
7.6
9 3 13 6
53.3 49.2
2.06 2.77
0.78 0.93
3.9 5.6
7.3 7.6 8.6
0.91 0.98 1.51
0.27 0.37 0.46
12.4 12.9 17.6
11 7 11 3
0 0 0 0
0 0 0 0
0 0 0 0
13 14 16 16
2.48 2.61 2.24 2.73
0.69 0.70 0.56 0.91
15.5 13.6 11.3 15.3
13 14 16 9
No. of basal body pairs in girdle kinety
No. of basal body pairs in ventral kinety
52 52 46 ca. 50 6 6 7 5
58 56 54 9 9 12 7
No. of macronucleus-segments
Length of macronucleus in ).1m
12 15 15 14
20 24 23 22
16.0 19.2 19.8 17.8
5 7 9 3
334
W. Song, M. Wang and A. Warren
14
13 16
,
.,
.
.'
. 1 . 1
/
~/
/
17
18
Fig. 10-19. Strombidium sulcatum from life (10-16) and after pro targol impregnation (17-19). 10. Ventral view of a typical individua l. 11. Portion of perilemma and the extru somes in v ivo. 12. Proposed process of formation of the polygona l platelets on perilemma. 13. Pattern of locomot ion . 14. Apical view, to show the prop ort ion of the buccal field/collar area to the cross section of the bod y. 15. A thick form with the posterior part clearly wider than the anterior. 16. To show different body shapes, not e th at the cell in the middle po ssesses fewer extrusomes. 17. Apical view of the buccal apparatus. 18, 19. Infraciliature of ventral and do rsal sides; note the lorica is clearly separated from the cytoplasm. BAM - buccal membranelles, CA M - collar membranelles, CK - circle kinety, Co - collar, Ex - extru somes, GEx - girdl e of extruso mes, Pe - perilemma, PM - paroral membrane, VK ventr al kinety. Scale bars in 10 = 25 pm; in 18, 19 = 20 pill.
Three Marine Oligotrichous Ciliates from China
peatedly reported or investigated with reference to its ecology, morphology, ultrastructure and other aspects of its biology [2, 4, 14, 18-20, 24, 26, 32, 33, 38, 42]. However, a detailed redescription concerning its morphology in vivo and infraciliature is still necessary because this species is highly variable in many respects, a fact that has been overlooked in many previous studies. Based on the data from the literature and from our own observations, we suggest here an improved diagnOSiS.
Improved diagnosis. Medium-sized marine Strombidium 30-50x25-40 pm in vivo with ovoidal body shape and conspicuous apical protrusion; 13-16 collar and 7-9 buccal membranelles; one macronucleus and one micronucleus; extrusomes prominent, ca. 12-15 pm long, around equatorial region; ventral kinety short and posteriorly positioned, usually consisting of 7-8 dikinetids; circle kinety closed, composed of ca. 50 dikinetids. Redescription of Chinese populations. Body shape slightly variable, but mostly broadly obconical to ellipsoidal, usually widest posterior of mid-body (Fig. 15, 16), while in newly divided cells posterior half often slightly tapering (Fig. 10, 16) as depicted by Kahl [24, 38]; length to width ratio about 2-3:2 and circular in cross-section (Fig. 14, 16). Apical protrusion, or collar, conspicuous in vivo but usually undetectable after impregnation. Buccal cavity extending to about 1/3 of cell length (Fig. 16). Cilia of most membranelles about 20 m long, extending anteriorly as shown in Figures 10 and 14. Pellicle with conspicuous perilemma, especially in some large individuals (Fig. 15). Cortical platelets displaying great diversity: In most cases, these platelets are numerous, polygonal in shape, of similar sizes and easily observed being positioned immediately underneath the cell surface (Fig. 11). In others, they are sparsely distributed, irregularly rounded in shape, of variable size, and rather inconspicuous being positioned at some distance beneath the cell surface within the alveolae, but nevertheless anchored in a specific position (Fig. 12, 33). This "abnormal" situation (without typical polygonal cortical platelets) possibly individual-dependent or relying on physiological or developing stages (e.g. newly divided). In this case, polygonal cortical platelets were impossible to recognise; rather the platelets are rounded or irregularly shaped and firmly positioned beneath the cell surface (Fig. 32, 33). Girdle groove most conspicuous around mid-body, below where the perilemma covers the cytoplasm. Margin of perilemma often inclined to cell surface (Fig. 10, 16). Cells colourless to slightly grey, containing numerous light-reflecting, lipid-like globules and large food vacuoles (ca. 5 pm across) usually containing small flagellates or diatoms, often rendering cells green or yel-
335
low-green in colour (Fig. 10, 15). Extrusomes prominent, about 15-20 pm long, closely spaced (often several in a bundle as shown in Fig. 11,32) anterior to margin of perilemma; when observed under higher magnification, the outer ends of extrusomes grouped 5-7 together, anchored beneath pellicle in orderly fashion, making the cell surface slightly protrude; extrusomes often seen as a band of dark dots after protargol impregnation (Fig. 18, 19). Occasionally cells can be seen with fewer, widely spaced extrusomes but they are not grouped together in this case (Fig. 16). Contractile vacuole not found. Macronucleus, ovoid to ellipsoidal, containing several to many large globular nucleoli (Fig. 19); micronucleus ovoid, about 2 pm long, near macronucleus (Fig. 19). Locomotion typical of pelagic oligotrichs being irregular and very fast (Fig. 13). Somatic ciliature consisting of two kineties: circle kinety around periphery, immediately anterior of perilemma, composed of approximately 50 dikinetids (Fig. 18, 19). Ventral kinety in shallow groove near caudal area, mostly with 7-8 densely spaced dikinetids (Fig. 18,35,37). Peristomial field relatively narrow, almost completely surrounded by adoral zone of membranelles (Fig. 14, 17). Bases of collar membranelles about 7-9 pm long, each composed of 3 basal body rows; buccal mernbranelles continuous with collar membranelles and gradually shortened posteriad (longest of bases about 5 pm long), invaginating centrally into mid-body. Single-rowed paroral membrane along right border of buccal cavity. Pharyngeal fibres up to 20 pm long. Remarks and comparison with related species. With reference to the abnormal cortical polygonal platelets in some specimens observed, we assume that they may represent different developing stages, but all cells concerned belong to the same species for they have similar general morphological as well as the infraciliatural features as "typical" forms. We propose here a hypothesis for this situation: the platelets first develop within the alveolae near the cell surface in low number and with a wide variety of shapes and sizes. These gradually join together and begin to anchor on/beneath the perilemma. As they increase in size and number, the platelets form into polygonal shapes because of the limited space available. This process is schematised in Figure 12. The position of the platelets suggested here is consistent with that demonstrated by Faure-Fremiet and Ganier [19] in their ultrastructural study of S. sul-
catum. The present study supports the conclusion given by Montagnes et al. [38] that Strombidium sulcatum should be identified by its body shape and size, the number of membranelles, dikinetids in circle and ven-
336
W. Song, M. Wang and A. Warren
Table 4. Morphometry of Strombidium sulcatum; comparison of data from present study with those from some previous ly reported S. sulcatum-populations. No.1, present study; No .2 after Lei er al [26]; No .3 after Montagnes et al. [38]; No.4 after Lynn et al. [32]; No.5 after Fenchel & Jonsson [20]; No.6 after Borror [2]. Character
No .1
No.2
N o.3
No.4
N o.5
N o.6
Body length in vivo (prn)
30-50
33-42
40-50
28-42
12.5-30':'
ca. 44
Body width in vivo (pm)
25-40
25-35
25-30
16-26
12.5-2F"
ca. 30
No . of collar membranelles
13-16
14-16
ca.12
12-15
12-15
12-13
No. of buccal membranelles
7-9
7-9
7-8
8-1 1
7-9
10-12
No. of basal body pairs in girdle kinety
46-56
ca. 50
No. of basal body pairs in ventral kinety
5-12
7-9
Apical protrusion in vivo
present
present
Apical protrusion after protargol impregnation
unde tectable
undetectable
Sample location
Qingdao, China
Qingdao, China
7-8 present
7-9 present absent (or artifact)
Limfjorden, Denmark
Gulf of Main, USA
Limfjorden, Denmark
Florida, USA
". Data from protargol impregnated specimens; ? Data not given.
tral kineties, as well as the app earance of the perile mma and extrusomes. We also approve their redefinition which was based on previous reports and descriptions (Table 4). Th e most ambiguo us charac ter for the recognition of S. sulcatum is the presence of the apical protrusion, by which this taxon may be clearly separated from other closely-related Strombidium species as indicated in some previous studies [32, 33, 38]. During our observa tions, we always fou nd that the apical pro trus ion can be clearly observe d in vivo but becomes comp letely unde tectable after protargol impregnation (even using Normaski differential interference microscopy). This indi cates that the "absence" of such protrusion in impreg nated specimens is an artefact produced by the fixation/staining procedure. It is reasonab le to assume that this disappearance of the apical protrusion during the silverstaining procedure also occurs in other oligotric hs, e.g. Strombidium conicum (viz . Figures 3d, c and g of [1]) and Strombidium tintinnodes [44]. Thus, we agree with Lei et a1. [26] that Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 should be conspecific (again) with S. sulcatum, as originally stated by Lynn et a1. [32], because the only difference between the two forms is that the former lacks an apical protrusion in impregnated specimens [32]. G en us Heterostrombidium Song, 1999 Th e genus Heterostrombidium was established by Song [43] based on a poorly-known form, H. calk insi
(Faur e-Fre miet, 1932) Song, 1999 (formerly Strom bidium calkinsi Faure -Fremiet, 1932). Since Hete rostrombidium has so far only been repo rted in the Chinese literature [43], we give here a summary of diagnostic characteristics of the genus. Di agn ostic cha racters for the genus H eterostrombidium: Strombidiidae with Strombidium-like somatic ciliature: circle kinet y around equatorial area, with ventral kinery located caudally; several long, specialized attaching membr anelles whic h are structurally ind ependent and connect with some collar membranelles on do rsal side; extrusomes and perilemma commonly present . H eterostrombidium differs from other known strombidiids in the presence of its specialized attaching membranelles on dorsal surface.
Heterostrombidium paracalkinsi Lei, Xu & Song, 1999 (Fig. 20-31, 43-47; Table 5) This species has been recently reported by Lei et al [27]. Because some information was lacking in the original description of this taxon, an additional contribution, based on our observations during the present study, is here provided along with an improved diagnoSIS.
Improved diagn osis. Small marine H eterostrombidium , 27-60 pmx30-50 pm in vivo; 15-17 collar and 7-9 buccal membranelies; 3 dorsal attachment mernbranelles connected to collar membranelles; girdle kinet y slightly open on ventral surface, comprising ca.
Three Marine Oligotrichous Ciliates from China
337
/
! 25
21
20
26 22
27
Fig. 20-31. Heterostrombidium paracalkinsi from life (20, 21, 23-27), after protargol impregnation (28-31) and Heterostrombidium calkinsi (from life). 20. Ventral view of a slender form. 21. A portion of cortex showing the platelets and the extrusomes (arrow). 22. An attached form of H. calkinsi (after Faure-Fremiet, 1932). 23-25. Showing attaching membranelles (arrows); 23, 24, to show different body shapes, lateral views; 25, to show creeping locomotion. 26, 27. To show the asymmetrical body shape (ventral and dorsal views). 28, 29. Ventral and dorsal view of the ciliary pattern. 30. Portion of dorsal view, to demonstrate the attaching dorsal membranelles. 31. Lateral view to show the newly-built oral primordium; note the 3 prolonged attaching dorsal membranelles continuous with the normal membranelles. AtM - attaching dorsal membranelles, BAM - buccal membranelles, CAM - collar membranelles, CK - circle kinety, GEx - girdle of extrusomes, Ma - macronucleus, PM - paroral membrane, VK - ventral kinety. Scale bars in 20, 23, 24 = 20 prn; in 28, 29 = 25 pm.
338
W. Song, M. Wang and A. Warren
Table 5. Morphom etric characterization of Heterostrombidium paracalkinsi. Data based on protargol-impregnated specimens [27]. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in pm Body width in pm No. of collar membranelles No. of buccal membranelles No. of basal body pairs in girdle kinety No. of basal body pairs in ventral kinety N o. of macronucleus-segments No. of micronuclei Length of macronucleus in pm Width of macronucleus in pm
27 30 15 7 44 8 1 1 15 13
43 42 17 9 56 16 1 1 25 18
36.0 34.8 15.9 8.1 48.4 10.1 1 1 19.6 15.4
4.4 3.5 0.6 0.5 2.9 1.4 0 0 2.3 1.5
1.0 0.8 0.1 0.1 0.7
12.3 10.2 3.7 6.7 6.1 13.9 0 0 11.9 10.0
20 20 18 13 17 19 20 20 20 20
44-56 dikinetids; posterior girdle kinety with 8-16 dikinetids; single ovoid macronucleus and spherical micronucleus. Description. In vivo 40-60x35-50 pm in size , body shape rather constant, broadl y ovoid to globular in sha pe, with conspicuous apical pr otrusion; posterior end rounded or only slightly nar ro wed (Fig . 20, 23-27). Buccal cavity extending to abo ut 1/3-2/5 of cell length. Perilemma tr ansparent, in po sterior half of body, w hich seems asy mme tric when viewe d fr om dorsoventral asp ect and is divided into tw o parts on vent ral side by the presen ce of ventral groove (Fig. 26, 27). Polygonal pl atel ets distinct (Fig. 21). Ex tr usomes about 15 pm long, in groups of ca. 5 each, insert ed anteriorly to edge of p eril emma (Fig. 21, 23, 24). Al ways with a V-shaped indentation on dorsal sid e beneath collar region where the att aching membranelles are located (Fig. 27). Cytoplasm colourless and hyaline, often containing nume rous lipid droplets (1---4 pm across), giving the cell a grey ish appearance. Food vacu oles large, several in number, often containing gree n- or yellow -coloured flagellat es. One macronuclear nodule, ovoid to ellipsoi dal w ith large globular nucleoli, centrally position ed; one globular micronucleu s attac hed to macronucleus (Fig. 28, 29). No contractile vacuoles observed. Cilia of membranelles of co llar area ca. 20 pm long, radi at ing outwards; three attaching membranelles abo ut 30 pm in length bending p osteriorly w hen swimmin g (Fig. 24, arrow), o r extending anteriad as shown
OJ
0 0 0.5
OJ
in Fi g. 23 while motionless (Fi g. 23, arro w ). Cells usually crawl on bottom of Petri dish with the help of th e thre e attaching membranelles, leavin g its vent ral side up (Fig. 25). C ircle kinety around edge of perilemma composed of approx imately 50 d iki netid s, with small gap on ventral sid e (Fig. 28-29). Ventral kinety in shallow groove with abo ut 10 dikinetids, extends fro m p osterior re gion almos t to equatorial kinety, usually slightly left of cytosto me (Fig. 28). Girdle of extrusomes distinct, about 4 pm wide, cont inuous on vent ral sid e (Fig. 28, 43). After impregnation, cells mo re bowl-like than ovo id (apical protrusion not recognizable), ofte n width of bod y greater than its len gth , with conspic uous bu ccal field (Fig. 28). Bases of collar membranelles about 10 pm long, each with 3 rows of kinetosomes; posterior to th em on dorsal side, 3 attaching membranelles about 15 pm long, each with only 2 rows of kinetosomes and positioned in shallow grooves, continuous with collar ones, extending posteriorly to equ atorial region of cell. Betw een and parallel to these attaching membranelles, argentophilic fibres alwa ys present (Fig. 30, 31, 46). About 8 bu ccal membranelles, each ca. 5 pm long and thus co nspic uo usly sho rt er th an co llar membranelles; each bu ccal membranelle co nsists of two row s of kin eto somes. Paroral membran e consists of monokinetids and lies alo ng margin of buccal cavit y (Fig. 28). Remarks and comparison with related species. One of th e most interestin g characteristics of thi s
Fig. 32-38. Strombidium sulcatum from life (32-34) and after protargol impregnation (35-38). 32. To show the extrusomes (large arrows) and "primary" platelets which are closely spaced (small arrows). 33. Arrows indicate the irregularly arranged "primary" platelets. 34. To show the groove where the ventral kinety is located (arrow). 35. Ventral view, to show the macronucleus (white arrow), extrusome girdle (small arrows), circle kin ety (double-arrowheads) and the ventral kinety (large arrow). 36,37. Ventral view to show the buccal membranelles(largearrow), newly-built oral primordium (small arrows) and the ventral kinety (white arrow). Note the "absence" of the apical protru sion (arrow in Fig. 36 and double-arrowheads in Fig. 37). 38. To show the extrusome girdle (arrow). Scale bars in 32 = 20 urn; in 35 = 25 pm.
Three Marine Oligotrichous Ciliates from China
+ I
I '\ \
339
" 33
32
// 35
• 36
37
38
340
W. Song, M. Wang and A. Warren
39
40
41
43
42
44
I
45
46
47
Three Marine Oligotrichous Ciliates from China genus/organism is the ongm of the attaching membranelles. Some individuals in early division stages, and at least one cell in the final division phase, were observed (Fig. 31). From these it can be seen that the attaching membranelles derive from the middle portion of the oral primordium, which also generates the other "normal" collar membranelles. It is also confirmed that the attaching membranelles, each of which consists of two rows of kinetosomes, originate as a prolonged part of related collar membranelles. In 1932, Faure-Fremiet described an unique Strombidium, S. calkinsi, which measures about 40 pm in length and has 2 very long (35-40 urn) attaching membranelles (Fig. 22) [16]. It is evidently very closely related to H. paracalkinsi. Since no information is available concerning the infraciliature of S. calkinsi, comparisons can only be made using its morphology in vivo. According to the original description, its body is "irregularly ovoid with a great antero-posterior axis; the hemispherical basal region is bounded by a transversal depression ...; the adoral sinistral zone surrounds the collar with 14 great membranelles...; a conical bundle of intracytoplasmic radiating rods fills the basal part of the body and clearly delineates the annular furrow... " [16]. Strombidium calkinsi is thus very similar to H. paracalkinsi, the main differences being that the former has 2 attaching membranelles that are distinctly separate from the adoral membranelles (vs. 3 in H. paracalkinsi that are continuous with the collar membranelles), and the fact that the manner of attachment when the cell is motionless is dissimilar (Fig. 22, 25). Since FaureFremiet [16] stressed repeatedly that his organism possesses two attaching membranelles, we believe that the number of such organelles should be considered as a reliable and critical character to separate these taxa. Acknowledgements: This work was supported by the "State 973 Research Program" (project number: G1999012001), the National Science Foundation of China (project number: 39970098), and an exquota travel award from the Royal Society of London to the senior author. We would like to thank Zigui Chen and Lei Yanli (College of Fisheries, Ocean University of Qingdao) for help with the photographic development and the collection of some of the samples, respectively.
341
References 1 Agatha S. and Riedel-Lorje J. C. (1997): Morphology, infraciliature, and ecology of halteriids and strombidiids (Ciliophora, Oligotrichea) from coastal brackish water basins. Arch. Protistenkd. 148,445-459. 2 Borror A. C. (1965): New and little known tidal marsh ciliates. Trans. Am. microsc. Soc. 84, 550-565. 3 Borror A. C. (1972): Tidal marsh ciliates (Protozoa): morphology, ecology, systematics. Acta Protozool. 10,29-71. 4 Buddenbrock W. (1920): Beobachtungen uber einige neue oder wenig bekannte marine Infusorien. Arch. Protistenkd. 41, 341-364. 5 Buddenbrock W. (1922): Ober eine neue StrombidiumArt aus Helgoland (Str. clavellinae). Arch. Protistenkd. 45, 129-132. 6 Burger O. (1908): Nuevos estudios sobre Protozoos chilenos del agua dulce. An. Univ. Chile 122, 137-204. 7 Busch W. (1921): Studien uber Ciliaten des Nordatlantischen Ozeans und Schwarzen Meeres. Arch. Protistenk. 42,364-378. 8 Busch W. (1930): Ober marine Strombidium-Arten aus der antarktischen allgemeinen Oststromung. Abh. Mus. Nat. Heimatk. Magdeburg. 4, 83-87. 9 Corliss J. O. (1979): The ciliated Protozoa: characterization, classification and guide to the literature. 2nd ed. Pergamon Press, London. 10 Czapik A. (1976): Strombidium grande Levander. Acta Protozool. 15,273-275. 11 Dragesco J. (1960): Cilie mesopsarnmiques littoraux. Systematique, morphologie, ecologic. Trav.Stn. bioI. Roscoff 12,1-356. 12 Dragesco J. and Dragesco- Kerneis A. (1986): Cilies libres de l'Afrique intertropicale. Faune tropic ale 26,1-559. 13 Entz G. (1884): Ober Infusorien des Golfes von Neapel. Mitt. zool. Stn. Neapel5, 289-444. 14 Faure-Fremiet E. (1911): tudes cytologiques sur quelques Infusoires des marais salants du Croisic. Arch. Anat. Microsc.13,401-479. 15 Faure-Frerniet E. (1924): Contribution a la connaissance des infusoires planktoniques. Bull. bioI. Fr. Belg. (suppl.) 6,1-171. 16 Faure-Frerniet E. (1932): Strombium calkinsi, a new thigmotactic species. BioI. Bull. 57, 201-204. 17 Faurc-Frcmict E. (1950): Ecologic des cilies psammophiles littoraux. Bull. biol. Fr. Belg. 84, 35-75. 18 Faure-Frcrnict E. (1969): Remarques sur la systematique des cilies Oligotrichida. Protistologica 5, 345-352. 19 Faure-Fremiet E. and Ganier M.-C. (1970): Structure fine du Strombidium sulcatum CI. et L. (Ciliata Oligotrichida). Protistologica 6, 207-223.
Fig. 39-47. Strombidium elegans (39-43) and Heterostrombidium paracalkinsi (43-47) after protargol impregnation. 39. Ventral view, to show the prolonged buccal membranelles (arrows). 40. Dorsal view to demonstrate the "extra" kinety fragment in the anterior region (arrow). 41. Ventral view, to show the cell full of diatoms (arrows). 42. Ventral view, to show the "extra" kinety fragment on the ventral side, posterior to the buccal field (arrows). 43, 47. To show the circle kinety (arrow in 47). 44. Dorso-lateral view, to show the macronucleus (arrow) and the attaching membranelies (white arrow). 45. Ventral view to show the buccal apparatus, arrow marks the paroral membrane, while the double arrowheads indicate the buccal membranelles. 46. Right-lateral view, to show the attaching membranelles (white arrow). Scalebars in 41 = 30 urn; in 44 = 35 }lm.
342
W. Song, M. Wang and A. Warren
20 Fenchel T. and Jonsson P.R. (1988): The functional biology of Strombidium sulcatum, a marine oligotrich ciliate (Ciliophora, Oligotrichina). Mar. Ecol. Prog. Ser. 48, 1-15 . 21 Florentin R. (1901): Description de deux infusoires cilies nouveaux des mares salees de Lorraine suivie de quelques considrations. AnnIs. Sci. nat. (Zool.) Paleontol, 12, 343-363. 22 Foissner W. (1994): Progress in taxonomy of planktonic freshwater ciliates. Mar. Microb. Food Webs 8, 9-35. 23 Foissner W., Blatterer H., Berger H . and Kohmann F. (1991): Taxonomische und Okologische Revision der Ciliaten des Saprobiensystems. Band I: Cyrtophorida, Oligotrichida, Hypotrichida, Colpodea, Miinchen: Inforrnationsberichte des Bayer. Landesamtes fr Wasserwirtschaft 1/91,1-478. 24 Kahl A. (1932): Urtiere oder Protozoa I: Wimpertiere oder Ciliata (Infusoria) 3. Spirotricha. Tierwelt Dtl, 25, 399-650. 25 Krainer K.-H. (1991): Contributions to the morphology, infraciliature and ecology of the planktonic ciliates Strombidium pelagicum n. sp., Pelagostrombidium mirabile (Penard, 1916) n. g., n. comb., and Pelagostrombidium fallax (Zacharias, 1896) n. g., n. comb. (Ciliophora, Oligotrichida). Europ. J. Protistol. 27, 60-70. 26 Lei Y., Xu K. and Song W. (1996): Ecological and morphological studies on Strombidium sulcatum, a harmful ciliate during algae cultivation. ]. Fish. Sci. Chin. 3, 39--47 (in Chinese with English summary). 27 Lei Y., Xu K. and Song W. (1999a): Morphological studies on a new ciliate, Heterostrombidium paracalkinesi nov. spec. from mariculture water (Ciliophora, Oligotrichida). Chin.]. Appl. Environ. BioI. 5, 181-184 (in Chinese with English summary). 28 Lei Y., Xu K. and Song W. (1999b): Free living ciliates from marine farming ponds. In: W. Song et al. (ed): Progress in Protozoology, pp. 269-295 (in Chinese). Qingdao Ocean Univ. Press, Qingdao. 29 Levander K. M. (1894): Materialien zur Kenntniss der Wasserfauna in der Umgebung von Helsingfors, mit besonderer Bcriicksichtigung der Meeresfauna 1. Protozoa . Acta Soc. Fauna Flora fenn 12, 1-115. 30 Lynn D. H. and Gilron G. L. (1993): Strombidiid ciliates from coastal waters near Kingston Harbour, Jamaica (Ciliophora, Oligotrichia, Strombidiidae). J. mar. bioI. Ass. U .K. 73, 47-65 . 31 Lynn D. H. and Montagnes D .]. S. (1988): Taxonomic description of some conspicuous species of strobilidiine ciliates (Ciliophora: Choreotrichia) from the Isles of Shoals, Gulf of Maine.]. mar. bioI. Ass. U.K. 68, 639-658. 32 Lynn D. H., Montagnes D . ]. S. and Small E. B. (1988): Taxonomic description of some conspicuous species in the family Strombidiidae (Ciliophora: Oligotrichida) from the Isles of Shoals, Gulf of Maine. ]. mar. bioI. Ass. U. K. 68, 259-276. 33 Maeda M. (1986): An illustrated guide to the species of the families Halteriidae and Strobilidiidae (Oligotrichida, Ciliophora), free swimming protozoa common in the aquatic environment. Bull. Ocean Res. Inst. Univ. Tokyo 21,1-67.
34 Maeda M. and Care y P. G. (1985): An illustrated guide to the species of the families Strombidiidae (Oligotrichida, Ciliophora), free swimming protozoa common in the aquatic environment. Bull. Ocean Res. Inst., Univ, Tokyo 19,1-68. 35 Martin A.]. and Montagnes D. J. S. (1993): Winter ciliates in a British Columbian Fjord: six new species and an analysis of ciliate putative pre y. J. Euk. Microbiol. 40, 535-549. 36 Montagnes D. ]. S. and Lynn D. H. (1991): Taxonomy of choreotrichs, the major marine planktonic ciliates, with emphasis on the aloricate forms. Mar. Microb. Food Webs 5,59-74. 37 Montagnes D.]. S. and Taylor F.]. R. (1994): The salient features of five marine ciliates in the class Spirotrichea (Oligotrichia), with notes on their culturing and behaviour.]. Euk. Microbiol. 41, 569-586. 38 Montagnes D.]. S., Taylor F. J. R. and Lynn D. H. (1990): Strombidium inclinatum n. sp. and a reassessment of Strombidium sulcatum Claparede and Lachmann (Ciliophora).]. Protozool. 37, 318-323. 39 Montagnes D.]. S., Lynn D . H., Stoecker D. K. and Small E. B. (1988): Taxonomic descriptions of one new species and redescription of four species in the family Strombidiidae (Ciliophora, Oligotrichida). ]. Protozool. 35, 189-197. 40 Petz W, Song W. and Wilbert N. (1995): Taxonomy and ecolog y of the ciliate fauna (Protozoa, Ciliophora) in the endopagial and pelagial of the Weddell Sea, Antarctica. Stapfia 40,1-223. 41 Sauerbrey E. (1928): Beobachtungen uber einige neue oder wenig bekannte marine Ciliaten. Arch. Protistenkd. 62,355--407. 42 Song W. (1996): Morphogenetic studies on Strombidium sulcatum (Ciliophora, Oligotrichida). Nat. Sci. Pro gr. China.6,16-25. 43 Song W. (1999): Infraciliature of oligotrichous ciliates at generic level. In: W. Song et al. (ed): Progress in Protozoology, pp. 155-176 (in Chinese). Qingdao Ocean Univ. Press, Qingdao. 44 Song W. and Bradbury P. C. (1998): Studies on some new and rare reported marine planktonic ciliates (Ciliophora: Oligotricha) from coastal waters in North China. J. mar. bioI. Ass. U.K. 78, 767-794. 45 Song Wand Packroff G. (1997): Taxonomische Untersuchungen an marin en Ciliaten aus China mit Beschreibungen von 2 neuen Arten, Strombidium globosaneum nov. spec. und Strombidium piatum nov. spec. (Protozoa, Ciliophora). Arch. Protistenkd. 147,331-360. 46 Song W., Wilbert N. and Warren A. (1999): Three new entocommensal ciliates from digestive tract of sea urchins of the Weddell Sea, Antarctica (Protozoa, Ciliophora). Polar BioI. 22, 232-240. 47 Wang C. C. (1934): Notes on the marine infusoria of Amo y. Mar. BioI. Ass. China, Annual Rep. 3, 50-70. 48 Wilbert N. (1975): Eine verbesserte Technik der Protargolimpragnation fur Ciliaten. Mikrokosmos 64,171-179. 49 Wilbert N . (1986): Beitrag zur Morphologic und Okologie einiger planktischer Ciliaten aus dem Poppelsdorfer Weiher in Bonn (BRD). Arch. Protistenkd. 131,59-69.
European Journal of
PROTISTOLOGY
Redescriptions of Three Marine Ciliates, Strombidium elegans Florentin, 1901, Strombidium sulcatum Claparede & Lachmann, 1859 and Heterostrombidium paracalkinsi Lei, Xu & Song, 1999 (Ciliophora, Oligotrichida) Weibo Sonq'>, Mei Wang 1 and Alan warren1
2
Laboratory of Protozoology, ARL, Ocean University of Qingdao, 266003 Qingdao, P.R. China Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
Summary The morphology and infraciliature of three marine oligotrich ciliates, Strombidium elegans Florentin, 1901, Strombidium sulcatum Claparede & Lachmann, 1859, and Heterostrombidium paracalkinsi Lei, Xu & Song, 1999, collected from coastal mollusc farming ponds near Qingdao (Yellow Sea, north China) are investigated based on observations of specimens in vivo and following protargol impregnation. Since no recent data deriving from modern studies on Strombidium elegans are available, a detailed redescription is given and some synonyms are suggested. As a commonly occurring form, further morphological and morphometrical data on S. sulcatum are supplied based on four populations from the Qingdao region. Other populations of Strombidium sulcatum reported previously in the literature are compared with our organisms and the taxonomic status of each is discussed. The genus Heterostrombidium Song, 1999 is a recently erected taxon characterised by the presence of a few dorsal attaching membranelles that are connected with "normal" collar membranelles on dorsal side. The relationship between H. paracalkinsi and H. calkinsi (Faure-Fremiet, 1932) Song, 1999 is discussed. Following a review of the data provided by previous investigators, four other taxa are synonymized thus; Strombidium sauerbreyae (Sauerbrey, 1928) sensu Faure-Frerniet, 1950 and S. armatum Burger, 1908 [synonyms of S. elegans]; Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 and S. lagenula Faure-Frerniet, 1924 [synonyms of S. sulcatum]. Additional notes on Heterostrombidium paracalkinsi Lei, Xu and Song, 1999, are also provided. "corresponding author: Dr. Weibo Song, College of Fisheries, Ocean University of Qingdao, Qingdao 266003, P. R. China; Fax: ++86 532 2032283,E-mail: [email protected] © 2000 by Urban & Fischer Verlag
Key words: Marine ciliates; Oligotrichina; Morphology and infraciliature; New species; Yellow Sea, China.
Introduction Oligotrichs are often the dominant planktonic ciliates in both marine and freshwaters. About 200 putative aloricate species belonging to the suborder Oligotrichina have been reported [1, 11, 23, 29, 34, 39, 43, 49]. Since most of these organisms are small, fragile and highly motile, over two thirds of them have been only superficially described, in most cases these descriptions being based only on live specimens or on material fixed using classical methods [7, 8, 10, 15,24]. Only approximately one third have been studied with the help of the protargol impregnation technique [3, 12,22,30,35-37, 40]. Consequently, many ambiguities concerning the identification of taxa within this species-rich group have accumulated and previously reported species are frequently misidentified or overlooked in ecological and taxonomic studies. This is mainly because certain diagnostic features (viz. behaviour or movement, extrusomes, body shape, cell colour etc.) can, in most cases, only be seen in living cells while others such as ciliary patterns and buccal structures can only be discerned in silver-impregnated cells or by electron microscopy, both of which require fixation. Thus, modern techniques, in which cells are observed in vivo as well as following silver impregnation, are regarded as essential for adequate species descriptions. Furthermore, careful comparisons with those forms reported in the 0932-4739/00/36/03-327 $ 15.00/0
328
W. Song, M. Wang and A. Warren
older literature must also be carried out, especially when erecting new taxa. Taxonomic studies of planktonic ciliates in coastal waters near Qingdao, north China have been carried out for over a decade and many populations/species of aloricate oligotrichs have been isolated and observed. Many of those isolated have never been studied using modern techniques, including several previously known forms. In this paper, the morphology of one commonly occurring, "well known" species and two poorly known species are described. The taxonomic status of several closely related taxa is also discussed.
Material and Methods
Sampling sites and ecological features Seawater samples were collected from open ponds used for mollusc mariculture in the Yellow Sea coastal regions near Qingdao, Shandong Province, China. Both field material and raw cultures, which were kept for several days or weeks in the laboratory, were used for morphological studies. Ecological characteristics for all sampling sites were similar: generally oligo- to mesosaprobic coastal waters, salinity 30-32%0, pH ca. 8.0-8.3, water temperature ranged from 5-24 dc. Two populations of Strombidium elegans Florentin, 1901 were isolated from coastal waters off Qingdao (Tsingtao), China (january 10,1995 and April 16, 1996). Four populations of Strombidium sulcatum Claparede & Lachmann, 1859 were isolated during the year 1995 (17 April, 18 July, 14 October and 11 November) from coastal waters off Qingdao and from neighbouring areas. They were found to occur in large number. H eterostrombidium paracalkinsi Lei, Xu & Song, 1999 was isolated once in low number from samples collected from the coastal waters near Qingdao (20 June, 1996).
Observations, staining and terminology In order to observe locomotion, all organisms were kept in Petri dishes with the water in which they were growing. They were observed first under a stereomicroscope (x64 magnification), and were then transferred onto microscope slides (without cover glasses) and observed at low magnifications (xl 00-200) under a compound microscope. All species were observed in vivo with phase contrast and differential interference contrast microscopy. The infraciliature was revealed by protargol impregnation [48]. Counts, drawings and measurements were performed at a magnification of x1250. Terminology is mainly according to Corliss [9], Lynn and Montagnes [31] and Krainer [25]. A few terms that might be confusing are explained in the following paragraphs. Buccal membranelles: (= ventral polykinetids) membranelles which are clearly separated from the collar membranelles and located along the buccal cavity. Circle kinety: (= girdle kinety or equatorial kinety) a single row of dikinetids which encircles the equatorial region of the cell.
Collar membranelles: (= anterior polykinetids) membranelles which occupy the collar region and encircle the apical protrusion. Extrusome girdle: (= circumferential girdle) belt-like structure on the surface of cell, usually around the equatorial region anterior to the circle kinety, which demonstrates the outer ends of extrusomes. In vivo it often consists of longitudinally arranged, granule-like, rough protrusions, while after protargol impregnation it appears as an independent girdle, containing densely arranged argyrophilic fibres or meshes. Perilemma: the outermost structure of the cell covering the whole pellicle, but most conspicuous around the posterior half of the cell and beneath which the polygonal cortical platelets are distributed. Ventral kinety: the short, postequatorial kinety, longitudinally oriented on ventral side (with exception) and usually located in the caudal region. Prolonged membranelles: belong to the collar membranelles but having considerably longer bases and cilia, and are usually used for attaching to a substrate.
Slide depositions Voucher slides of protargol-impregnated specimens of Strombidium elegans are deposited in the Natural History Museum, London with the following registration number: Strombidium elegans; 2000:01:01:01 and 2000:01:01:02. For Heterostrombidium paracalkinsi, one paratype slide is deposited in the NHM with registration number; 2000: 01:01:03 (the holotype is deposited in the Laboratory of Protozoology, College of Fisheries, Ocean University of Qingdao, P. R. China).
Results Family Strombidiidae Faure-Fremiet, 1969 Genus Strombidium Claparede & Lachmann, 1859
Strombidium elegans Florentin, 1901 (Fig. 1-9, 39-42; Table 1) Syn. S. armatum Burger, 1908 S. sauerbreyae sensu Faure-Fremiet, 1950 Spirostrombidium elegans (Florentin, 1901) Petz, Song & Wilbert, 1995 To the authors' knowledge, this species has never been investigated using modern methods, so we here supply a redescription based on an examination of the present populations. Improved diagnosis. Medium-sized, marine Strombidium 30-50x20-30 pm in vivo with somewhat asymmetric, slim-cordate outline when viewed dorsa-ventrally and with pointed posterior end; 12-15 collar and 8-10 buccal membranelles; 2 posteriorly-directed prolonged membranelles; one macronucleus and one micronucleus; extrusomes prominent, ca. 7-10 pm long, arranged along cell margins; circle kinety consisting of 30-44 dikinetids, open on ventral side with both arms
Three Marine Oligotrichous Ciliates from China
329
Table 1. Morphometric characterization of Strombidium elegans-population I (line 1) and population II (line 2). Data based on protargol-impregnated specimens. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in pm
31 27
51 47
36.3 38.8
3.59 4.3
0.90 1.01
9.9 11.1
16 18
Body width in urn
16 18
27 26
20.1 21.2
2.13 3.7
0.54 0.87
10.6 17.5
16 18
12
21
14.7
1.66
0.42
11.3
16
No. of collar membranelles'"
12 13
14 15
12.9 13.9
0.83 0.7
0.22 0.2
6.4 5.1
14 19
No. of buccal membranelles
8 9
10 10
9.1 9.2
0.74 0.4
0.23 0.1
8.1 4.5
10 19
No. of basal body pairs in girdle kinety
30 37
39 44
34.1 40.5
3.18 2.3
0.88 0.6
9.3 5.7
13 17
No. of basal body pairs in ventral kinety
11 9
21 11
13.5 10.4
3.55 0.7
0.98 0.2
23.0 6.7
13 19
No. of macronucleus-segments
0 0
0 0
0 0
11 18
No. of micronuclei
0 0
0 0
0 0
9 18
~istance III
from apex to cytostome'
pm
Length of macronucleus in pm
11 18
18 28
13.9 24.4
2.22 2.9
0.56 0.7
16.0 11.7
16 16
10
18
14.9
2.2
0.5
14.6
16
Width of macronucleus in pm ':. Measured from anteriormost to the posterior end of buccal zone of membranelles; ':"'Including the prolonged membranelles.
shifted caudally; about 9-21 dikinetids in ventral kinety which is twisted towards the left. Redescription. Cell size in vivo mostly about 35-45 )lm in length. Body shape asymmetric, elongate cordate or obconical often with caudal part slightly twisted to right (Fig. 1); when viewed from ventral aspect, broadest part of cell always at "shoulder" area with caudal end more or less pointed; length to width ratio about 3:2 depending on stage in life cycle (Fig. 1, 5, 6). Dorsoventrally about 2:3 flattened (Fig. 4). Prominent apical protrusion (collar) distinct in vivo, but may disappear or be undetectable after fixation (Fig. 5-9). Buccal cavity deep, extending to about 1/3-2/5 of cell length (Fig. 1, 5, 6). Cilia of most membranelles about 20 )lm long, extending anteriorly as shown in Figures 1 and 3; cilia of two prolonged membranelles 30-50 )lm in length (depending on cell size), and always directed posteriorly like two tails (Fig. 1). Cells not very fragile, pellicle rather delicate with thin perilemma covering most of cell, but with no rec-
ognizable polygonal cortical platelets (Fig. 1). No distinct girdle present. Cytoplasm colourless to greyish, sometimes yellow-green due to ingested diatoms (Fig. 1, 4). Cell often containing several small globular lipid-like inclusions, 2-4 )lm across (Fig. 1). Food vacuoles few in number, frequently replete with very large diatoms (Fig. 39,41). Extrusomes prominent, about 10 )lm long, usually evenly spaced around periphery of the whole cell with exception of anteriormost region when viewed from ventral side (Fig. 1,5); in some small cells, probably following cell division, extrusomes sparsely arranged (Fig. 6). Contractile vacuole not found. Single macronucleus, ovoid to ellipsoidal, containing several large globular nucleoli (Fig. 5-7); single ovoid micronucleus about 2 )lm long, attached to macronucleus (Fig. 7). Locomotion with two main patterns: very fast and irregular when swimming (Fig. 2), or slow and even motionless for long periods when crawling over surfaces, using its 2 prolonged membranelles for attachment with ventral side down (Fig. 3).
330
W Song, M. Wang and A. Warren
J~ 2
1 3
!-
.." k
- CK
-
,.-
I
~~
\.,.--/
8
- -. / •
," \.......
"
I~
9
Fig. 1-9. Strombidium elegans from life (1-6) and after protargol impregnation (7-9). 1. Typical individual, ventral view. 2. Pattern of locomotion. 3. To show the creeping state, note the cell attached to the substrate with its two prolonged rnernbranelles, 4. Lateral view. 5, 6. To demonstrate the different body shapes. 7. Ventral view of ciliary pattern, arrow indicating the left arm of circle kinety; note that the ventral kinety is located in the right margin of cell. 8, 9. Ventral and dorsal view, to show some "extra" kinety fragments extrusornes (arrows); note that the "extra" kinety fragment extends over dorsal side. BAM - buccal membranelles, CAM - collar mernbranelles, CK - circle kinety, Co - collar, ExK - extra kinety, Ma - macronucleus, Mi - micronucleus, Pe - perilernma, Pm - prolonged membranelles, PM - par oral membrane, VK - ventral kinety. Scale bars in 1, 4-6 =25 pm; in 8, 9 =15 urn.
Somatic ciliature rather variable, basically consisting of one circle and one ventral kinety. Circle kinety shifted strongly posteriad on ventral side with both arms often slightly overlapping and forming a small gap through which ventral kinety inserts (Fig. 7-9). The Iat-
rer is usually long, extending to about 1/3 of body length and situated in shallow groove, distinctly shifted to right margin of cell (Fig. 7, 8). Some specimens (fewer than 1/3 of total individuals observed) possessing a fragment-like "extra" kinety, which is positioned
Three Marine Oligotrichous Ciliates from China
around "shoulder" area of cell and is composed of up to 15 or more sparsely arranged basal body pairs (Fig. 8,9, 42). In most cases, the extra kinety is very short and located either ventrally, posterior to buccal field, or on dorsal side, directly posterior to collar membranelles (Fig. 40). Extrusome girdle not observed. Buccal apparatus as shown in Figures 7 and 8. Buccal membranelles continuous with collar membranelles, invaginated into buccal cavity (Fig. 7). Bases of two prolonged collar membranelles about 12-15 pm in length (about twice as long as the other membranelles), positioned between collar and buccal membranelles (Fig. 7, 39). Paroral membrane on right wall of buccal cavity, extending to centre of apical protrusion; pharyngeal fibres about 7-20 pm long (Fig. 7, 8). Remarks and comparison with related species. In 1995, Petz, Song & Wilbert - without knowledge of its infraciliature - transferred this species into the genus Spirostrombidium, which is characterised thus: " ... equatorial kinety long and spiralling, viz. transversely encircling almost completely ventral and dorsal side and extending in wide spiral almost to or across posterior pole ... " [40]. According to the present study, the circle kinety of this species is neither spiral nor open but only highly "shifted" to the posterior area on ventral side. This species is therefore returned to the genus Strombidium. Our populations correspond well with Florentin's original description with reference to the basic morphology (the asymmetric body shape, size, etc.) and habitat [21]. Florentin [21], however, observed two contractile vacuoles in his organism. whereas no contractile vacuoles were observed in our population. We surmise that this character is either salinity-dependent or was misinterpreted by Florentin. In Florentin's drawing [21], the cell is depicted as possessing several prolonged membranelles among the collar mernbranelles rather than just two. Since this phenomenon was also observed by us in some newly divided cells, we assume that it represents a morphological variation. Finally, although Florentin [21] depicted the extrusomes as being present only on the dorsal side of the cell rather than around the periphery of the whole cell, we noted the arrangement of extrusomes varied somewhat according to the stage of the life cycle. The infraciliature of Strombidium armatum Burger, 1908 is still unknown. Based on the cell size, the general morphological appearance, distribution of extrusomes and the slightly prolonged membranelles, we surmise that it might be synonymized with the S. elegans. In 1950, Faure-Fremiet [17] described a form under the name "S. sauerbreyae Kahl" [24], despite the fact that its morphology is quite unlike that of the original [41]. Rather, it bears a strong resemblance to S. elegans, so it is here considered conspecific with the latter.
331
To date, approximately ten species of Strombidium with flattened body shape inhabiting marine biotopes have been reported [5, 6, 17,24,29,41,45-47]. However, few of these have been described using modern methods and this yields further confusion in terms of species separation and identification. The key morphological features of each of these taxa are given in Table 2. With reference to the morphologically related species (Table 2), Spirostrombidium cinctum (Kahl, 1932) Petz, Song & Wilbert, 1995 seems to be most similar to S. elegans. Although its infraciliature has not been described, S. cinctum can be distinguished by the distribution of extrusomes which are arranged around the entire cell margin (vs. absent from anteriormost region of cell in S. elegans), the deeply extended buccal field (ca. 1/2 vs. ca. 113 in S. elegans) and the absence of the prolonged membranelles (vs. present in S. elegans). Strombidium clavellinae Buddenbrock, 1922 is also very similar to S. elegans in terms of its general appearance [5]. It differs, however, in having four prolonged membranelles (vs. 2 in S. elegans), a rotund body shape (vs. elongate in S. elegans), and a much higher number of membranelles (total of buccal and collar membranelles 32-35 vs. 20-24 in S. elegans). The slender species, S. schizonstomum Kahl, 1932, the infraciliature of which is also unknown, exhibits a very different body shape (cylindrical), a conspicuously depressed girdle region in equatorial area, and possibly absence of the prolonged collar membranelles, all of which are in contrast to S. elegans. In 1932, Kahl reported a new species, Strombidium latum, which is characterized by its large size (100-140 pm long), many buccal membranelles, flat and wide oval body shape, and with extrusomes distributed throughout the cell [24]. Subsequently, Faure-Frerniet described a "population" of this taxon which he misidentified and very likely represents a separate, valid species [17]. Faure-Fremiet's isolate is characterized by its deeply extended buccal field (ca. 2/3 of body length), presence of 2 prolonged membranelles (vs. absent in S. latum) and with numerous buccal and collar rnembranelles (> 35). Strombidium elegans differs from the two organisms mentioned above, mainly in terms of body size (30-50 pm in S. elegans vs. > 100 urn) and in having fewer membranelles (8-10 in S. elegans vs. "numerous" as depicted by Kahl [24] and Faure-Frerniet [17]) (Table 2). Comparisons should also be made with two morphologically similar Spirostrombidium species: S. platum Song & Packroff, 1997 and S. echini Song, Wilbert & Warren, 1999. The latter is an endocommensal form inhabiting in digestive tract of sea urchins. It possesses an open circle kinety, the posterior end of which is divided into two parts giving the impression that this species has 2 ventral kineties [46], while the former is
Kahl, 1932
Data resource
Kahl, 1932
mesosaprobic (marine)
girdle groove conspICUOUS manne
Wang, 1934
manne sand Kahl, 1932
extrusomes all through cell margin
,,- Assumed from the illustrations; ,,-,,- Ventral kinety (VK) divided into 2 parts; ? Data unavailable or structure difficult to judge (or doubtful if present)
marine & brackish water
Habitats/biotopes or lifestyle (free-living if not otherwise specified)
Other features
1999
& Song,
Lei,Xu
manne
circle kinety open
87-121
-
-
-
present (3)
absent
13-16
ca. 12"-
absent
Number of dikinetids in circle kinety
absent?
absent?
Prolonged buccal adoral membranelles
ca. 2/3
ca. 1/3
ca. 1/3
absent
FaureFremiet, 1950
manne
original
mesosaprobic (marine)
body disgirdle symmetric groove conspICUOUS
37-44
present (2)
present (2)
endocommensal (marine)
Song, Wilbert & Warren, 1999
Buddenbrock, 1922
with "2" ventral kineties ,,-,,manne
-
>70
absent
19-24
ca. 25"-
12-15
present (4)
15-18
15-18
ca. 10"-
8-10
Song & Packroff, 1997
mesosaprobic (marine)
no ventral kinety
8-11
ca. 1/3
<1/4
1/4-1/3
conical
70-100
113-1/2
conical to ovoid
50-70
No. 10
widely oval
70-80
30-50
No.9
slimconic
No.8
No.7
ca.Ifi"
>20"-
widely oval
110-170
No.6
widely oval
20-22
>20"-
ca. 15'f
>15"-
No. of collar membranelles
70-80
36-55 cordate
No.5
No.4
ca. 20"-
>15"-
ca. 15"-
ca. 15"-
Length of buccal field: body length
No. of buccal adoral membranelles
cordate
Body shape ca. 2/5
100 -140
ca. 2/5
50-70
No.3
ca. 1/2
40-50
No.2
pot-like
(in vivo)
No.1
elongated
m]lm
C~lliength
Characters
Strombidium schizostomum Kahl, 1932 (No.2); Strombidium latum Kahl, 1932 (No.3); Strombidium pseudocinetum Wang, 1934 (No.4); Spirostrombidium urceolare (Stein in Faure-Frerniet, 1932) Lei et ai, 1999 (No.5); Strombidium latum sensu Faure-Frerniet, 1950 (No.6); Strombidium elegans Florentin, 1901 (No.7); Strombidium clavellinae Buddenbrock, 1922 (No.8); Spirostrombidium echini Song, Wilbert & Warren, 1999 (No.9) and Spirostrombidium platum Song & Packroff, 1997(No.10).
Table 2. Morphometric comparison of some marine, elegans-similar species with flattened body shape. Measurements in ]lm. Strombidium cinctum Kahl, 1932 (No.1);
w
::::J
;:0
;J> ~ (l) ....,
o,
::::J
(l)
1O
~ ::::J
'P :5:
::::J
0
VI
:::E
N
W
Three Marine Oligotrichous Ciliates from China
large (70-100 pm in length) and lacks a ventral kinety [45]. Based on these characters, both are clearly separated from S. elegans. Three morphological similar species from the genus Spirostrombidium, S. pseudocinctum (Wang, 1934) Petz, Song & Wilbert, 1995, S. oblongum (Entz, 1884) Petz, Song & Wilbert, 1995, and S. sauerbreyae (Sauerbrey, 1928) Petz, Song & Wilbert, 1995, can easily be distinguished from S. elegans on the basis of body shape, arrangement of extrusomes and general appearance of buccal membranelles [13,24,41,47]. Strombidium urceolare Stein in Faure-Fremiet, 1932 was re-identified only very recently [16, 28] and has been transferred to the genus Spirostrombidium as Spirostrombidium urceolare (Stein in Faure-Fremiet, 1932) Lei, Xu & Song, 1999. It differs from S. elegans in several respects, e.g. the number of attachment or-
333
ganelles (3 vs. 2), the ciliary pattern (girdle kinety open vs. girdle kinety closed and inserted by ventral kinety), the larger cell size (70-80 vs. 30-50 pm), and the number of buccal membranelles (13-16 vs. 8-10), collar membranelles (20-22 vs. 12-15) and dikinetids in the circle kinety (87-121 vs. 37-44) (Table 2).
Strombidium sulcatum Claparede & Lachmann, 1859 (Fig. 10-19,32-38; Table 3) Syn. Strombidium lagenula Faure-Frerniet, 1924 (?) Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 This supposedly well-known species has a cosmopolitan distribution and has been found in most kinds of marine biotope. For over 100 years, it has been re-
Table 3. Morphometric characterization of 4 populations of Strombidium sulcatum. Data from the authors and based on protargol impregnated specimens. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in urn
30 38 36 34
47 46 44 47
37.3 41.0 39.6 37.4
5.05 2.48 2.91 3.26
1.40 0.66 0.88 0.82
13.6 6.1 7.3 8.7
13 14 13 16
Body width in ).1m
24 26 32 25
34 33 41 33
28.0 29.2 37.2 27.8
3.11 2.05 2.49 2.37
0.86 0.55 0.69 0.59
11.1 3.4 6.7 8.5
13 14 13 16
No. of collar membranelles
13 14 14 14
15 15 16 15
13.7 14.2 14.6
0.71 0.60 0.77
0.24 0.17 0.22
5.2 4.2 5.3
9 13 13 4
No. of buccal membranelles
7 8 7 8
9 9 9 9
8.1
0.78
0.26
9.6
8.4
0.65
0.18
7.6
9 3 13 6
53.3 49.2
2.06 2.77
0.78 0.93
3.9 5.6
7.3 7.6 8.6
0.91 0.98 1.51
0.27 0.37 0.46
12.4 12.9 17.6
11 7 11 3
0 0 0 0
0 0 0 0
0 0 0 0
13 14 16 16
2.48 2.61 2.24 2.73
0.69 0.70 0.56 0.91
15.5 13.6 11.3 15.3
13 14 16 9
No. of basal body pairs in girdle kinety
No. of basal body pairs in ventral kinety
52 52 46 ca. 50 6 6 7 5
58 56 54 9 9 12 7
No. of macronucleus-segments
Length of macronucleus in ).1m
12 15 15 14
20 24 23 22
16.0 19.2 19.8 17.8
5 7 9 3
334
W. Song, M. Wang and A. Warren
14
13 16
,
.,
.
.'
. 1 . 1
/
~/
/
17
18
Fig. 10-19. Strombidium sulcatum from life (10-16) and after pro targol impregnation (17-19). 10. Ventral view of a typical individua l. 11. Portion of perilemma and the extru somes in v ivo. 12. Proposed process of formation of the polygona l platelets on perilemma. 13. Pattern of locomot ion . 14. Apical view, to show the prop ort ion of the buccal field/collar area to the cross section of the bod y. 15. A thick form with the posterior part clearly wider than the anterior. 16. To show different body shapes, not e th at the cell in the middle po ssesses fewer extrusomes. 17. Apical view of the buccal apparatus. 18, 19. Infraciliature of ventral and do rsal sides; note the lorica is clearly separated from the cytoplasm. BAM - buccal membranelles, CA M - collar membranelles, CK - circle kinety, Co - collar, Ex - extru somes, GEx - girdl e of extruso mes, Pe - perilemma, PM - paroral membrane, VK ventr al kinety. Scale bars in 10 = 25 pm; in 18, 19 = 20 pill.
Three Marine Oligotrichous Ciliates from China
peatedly reported or investigated with reference to its ecology, morphology, ultrastructure and other aspects of its biology [2, 4, 14, 18-20, 24, 26, 32, 33, 38, 42]. However, a detailed redescription concerning its morphology in vivo and infraciliature is still necessary because this species is highly variable in many respects, a fact that has been overlooked in many previous studies. Based on the data from the literature and from our own observations, we suggest here an improved diagnOSiS.
Improved diagnosis. Medium-sized marine Strombidium 30-50x25-40 pm in vivo with ovoidal body shape and conspicuous apical protrusion; 13-16 collar and 7-9 buccal membranelles; one macronucleus and one micronucleus; extrusomes prominent, ca. 12-15 pm long, around equatorial region; ventral kinety short and posteriorly positioned, usually consisting of 7-8 dikinetids; circle kinety closed, composed of ca. 50 dikinetids. Redescription of Chinese populations. Body shape slightly variable, but mostly broadly obconical to ellipsoidal, usually widest posterior of mid-body (Fig. 15, 16), while in newly divided cells posterior half often slightly tapering (Fig. 10, 16) as depicted by Kahl [24, 38]; length to width ratio about 2-3:2 and circular in cross-section (Fig. 14, 16). Apical protrusion, or collar, conspicuous in vivo but usually undetectable after impregnation. Buccal cavity extending to about 1/3 of cell length (Fig. 16). Cilia of most membranelles about 20 m long, extending anteriorly as shown in Figures 10 and 14. Pellicle with conspicuous perilemma, especially in some large individuals (Fig. 15). Cortical platelets displaying great diversity: In most cases, these platelets are numerous, polygonal in shape, of similar sizes and easily observed being positioned immediately underneath the cell surface (Fig. 11). In others, they are sparsely distributed, irregularly rounded in shape, of variable size, and rather inconspicuous being positioned at some distance beneath the cell surface within the alveolae, but nevertheless anchored in a specific position (Fig. 12, 33). This "abnormal" situation (without typical polygonal cortical platelets) possibly individual-dependent or relying on physiological or developing stages (e.g. newly divided). In this case, polygonal cortical platelets were impossible to recognise; rather the platelets are rounded or irregularly shaped and firmly positioned beneath the cell surface (Fig. 32, 33). Girdle groove most conspicuous around mid-body, below where the perilemma covers the cytoplasm. Margin of perilemma often inclined to cell surface (Fig. 10, 16). Cells colourless to slightly grey, containing numerous light-reflecting, lipid-like globules and large food vacuoles (ca. 5 pm across) usually containing small flagellates or diatoms, often rendering cells green or yel-
335
low-green in colour (Fig. 10, 15). Extrusomes prominent, about 15-20 pm long, closely spaced (often several in a bundle as shown in Fig. 11,32) anterior to margin of perilemma; when observed under higher magnification, the outer ends of extrusomes grouped 5-7 together, anchored beneath pellicle in orderly fashion, making the cell surface slightly protrude; extrusomes often seen as a band of dark dots after protargol impregnation (Fig. 18, 19). Occasionally cells can be seen with fewer, widely spaced extrusomes but they are not grouped together in this case (Fig. 16). Contractile vacuole not found. Macronucleus, ovoid to ellipsoidal, containing several to many large globular nucleoli (Fig. 19); micronucleus ovoid, about 2 pm long, near macronucleus (Fig. 19). Locomotion typical of pelagic oligotrichs being irregular and very fast (Fig. 13). Somatic ciliature consisting of two kineties: circle kinety around periphery, immediately anterior of perilemma, composed of approximately 50 dikinetids (Fig. 18, 19). Ventral kinety in shallow groove near caudal area, mostly with 7-8 densely spaced dikinetids (Fig. 18,35,37). Peristomial field relatively narrow, almost completely surrounded by adoral zone of membranelles (Fig. 14, 17). Bases of collar membranelles about 7-9 pm long, each composed of 3 basal body rows; buccal mernbranelles continuous with collar membranelles and gradually shortened posteriad (longest of bases about 5 pm long), invaginating centrally into mid-body. Single-rowed paroral membrane along right border of buccal cavity. Pharyngeal fibres up to 20 pm long. Remarks and comparison with related species. With reference to the abnormal cortical polygonal platelets in some specimens observed, we assume that they may represent different developing stages, but all cells concerned belong to the same species for they have similar general morphological as well as the infraciliatural features as "typical" forms. We propose here a hypothesis for this situation: the platelets first develop within the alveolae near the cell surface in low number and with a wide variety of shapes and sizes. These gradually join together and begin to anchor on/beneath the perilemma. As they increase in size and number, the platelets form into polygonal shapes because of the limited space available. This process is schematised in Figure 12. The position of the platelets suggested here is consistent with that demonstrated by Faure-Fremiet and Ganier [19] in their ultrastructural study of S. sul-
catum. The present study supports the conclusion given by Montagnes et al. [38] that Strombidium sulcatum should be identified by its body shape and size, the number of membranelles, dikinetids in circle and ven-
336
W. Song, M. Wang and A. Warren
Table 4. Morphometry of Strombidium sulcatum; comparison of data from present study with those from some previous ly reported S. sulcatum-populations. No.1, present study; No .2 after Lei er al [26]; No .3 after Montagnes et al. [38]; No.4 after Lynn et al. [32]; No.5 after Fenchel & Jonsson [20]; No.6 after Borror [2]. Character
No .1
No.2
N o.3
No.4
N o.5
N o.6
Body length in vivo (prn)
30-50
33-42
40-50
28-42
12.5-30':'
ca. 44
Body width in vivo (pm)
25-40
25-35
25-30
16-26
12.5-2F"
ca. 30
No . of collar membranelles
13-16
14-16
ca.12
12-15
12-15
12-13
No. of buccal membranelles
7-9
7-9
7-8
8-1 1
7-9
10-12
No. of basal body pairs in girdle kinety
46-56
ca. 50
No. of basal body pairs in ventral kinety
5-12
7-9
Apical protrusion in vivo
present
present
Apical protrusion after protargol impregnation
unde tectable
undetectable
Sample location
Qingdao, China
Qingdao, China
7-8 present
7-9 present absent (or artifact)
Limfjorden, Denmark
Gulf of Main, USA
Limfjorden, Denmark
Florida, USA
". Data from protargol impregnated specimens; ? Data not given.
tral kineties, as well as the app earance of the perile mma and extrusomes. We also approve their redefinition which was based on previous reports and descriptions (Table 4). Th e most ambiguo us charac ter for the recognition of S. sulcatum is the presence of the apical protrusion, by which this taxon may be clearly separated from other closely-related Strombidium species as indicated in some previous studies [32, 33, 38]. During our observa tions, we always fou nd that the apical pro trus ion can be clearly observe d in vivo but becomes comp letely unde tectable after protargol impregnation (even using Normaski differential interference microscopy). This indi cates that the "absence" of such protrusion in impreg nated specimens is an artefact produced by the fixation/staining procedure. It is reasonab le to assume that this disappearance of the apical protrusion during the silverstaining procedure also occurs in other oligotric hs, e.g. Strombidium conicum (viz . Figures 3d, c and g of [1]) and Strombidium tintinnodes [44]. Thus, we agree with Lei et a1. [26] that Strombidium inclinatum Montagnes, Taylor & Lynn, 1990 should be conspecific (again) with S. sulcatum, as originally stated by Lynn et a1. [32], because the only difference between the two forms is that the former lacks an apical protrusion in impregnated specimens [32]. G en us Heterostrombidium Song, 1999 Th e genus Heterostrombidium was established by Song [43] based on a poorly-known form, H. calk insi
(Faur e-Fre miet, 1932) Song, 1999 (formerly Strom bidium calkinsi Faure -Fremiet, 1932). Since Hete rostrombidium has so far only been repo rted in the Chinese literature [43], we give here a summary of diagnostic characteristics of the genus. Di agn ostic cha racters for the genus H eterostrombidium: Strombidiidae with Strombidium-like somatic ciliature: circle kinet y around equatorial area, with ventral kinery located caudally; several long, specialized attaching membr anelles whic h are structurally ind ependent and connect with some collar membranelles on do rsal side; extrusomes and perilemma commonly present . H eterostrombidium differs from other known strombidiids in the presence of its specialized attaching membranelles on dorsal surface.
Heterostrombidium paracalkinsi Lei, Xu & Song, 1999 (Fig. 20-31, 43-47; Table 5) This species has been recently reported by Lei et al [27]. Because some information was lacking in the original description of this taxon, an additional contribution, based on our observations during the present study, is here provided along with an improved diagnoSIS.
Improved diagn osis. Small marine H eterostrombidium , 27-60 pmx30-50 pm in vivo; 15-17 collar and 7-9 buccal membranelies; 3 dorsal attachment mernbranelles connected to collar membranelles; girdle kinet y slightly open on ventral surface, comprising ca.
Three Marine Oligotrichous Ciliates from China
337
/
! 25
21
20
26 22
27
Fig. 20-31. Heterostrombidium paracalkinsi from life (20, 21, 23-27), after protargol impregnation (28-31) and Heterostrombidium calkinsi (from life). 20. Ventral view of a slender form. 21. A portion of cortex showing the platelets and the extrusomes (arrow). 22. An attached form of H. calkinsi (after Faure-Fremiet, 1932). 23-25. Showing attaching membranelles (arrows); 23, 24, to show different body shapes, lateral views; 25, to show creeping locomotion. 26, 27. To show the asymmetrical body shape (ventral and dorsal views). 28, 29. Ventral and dorsal view of the ciliary pattern. 30. Portion of dorsal view, to demonstrate the attaching dorsal membranelles. 31. Lateral view to show the newly-built oral primordium; note the 3 prolonged attaching dorsal membranelles continuous with the normal membranelles. AtM - attaching dorsal membranelles, BAM - buccal membranelles, CAM - collar membranelles, CK - circle kinety, GEx - girdle of extrusomes, Ma - macronucleus, PM - paroral membrane, VK - ventral kinety. Scale bars in 20, 23, 24 = 20 prn; in 28, 29 = 25 pm.
338
W. Song, M. Wang and A. Warren
Table 5. Morphom etric characterization of Heterostrombidium paracalkinsi. Data based on protargol-impregnated specimens [27]. CV - coefficient of variation in %, Max - maximum, Mean - arithmetic mean, Min - minimum, n - number of specimens investigated, SD - standard deviation, SE - standard error of the mean. Character
Min
Max
Mean
SE
SD
CV
n
Body length in pm Body width in pm No. of collar membranelles No. of buccal membranelles No. of basal body pairs in girdle kinety No. of basal body pairs in ventral kinety N o. of macronucleus-segments No. of micronuclei Length of macronucleus in pm Width of macronucleus in pm
27 30 15 7 44 8 1 1 15 13
43 42 17 9 56 16 1 1 25 18
36.0 34.8 15.9 8.1 48.4 10.1 1 1 19.6 15.4
4.4 3.5 0.6 0.5 2.9 1.4 0 0 2.3 1.5
1.0 0.8 0.1 0.1 0.7
12.3 10.2 3.7 6.7 6.1 13.9 0 0 11.9 10.0
20 20 18 13 17 19 20 20 20 20
44-56 dikinetids; posterior girdle kinety with 8-16 dikinetids; single ovoid macronucleus and spherical micronucleus. Description. In vivo 40-60x35-50 pm in size , body shape rather constant, broadl y ovoid to globular in sha pe, with conspicuous apical pr otrusion; posterior end rounded or only slightly nar ro wed (Fig . 20, 23-27). Buccal cavity extending to abo ut 1/3-2/5 of cell length. Perilemma tr ansparent, in po sterior half of body, w hich seems asy mme tric when viewe d fr om dorsoventral asp ect and is divided into tw o parts on vent ral side by the presen ce of ventral groove (Fig. 26, 27). Polygonal pl atel ets distinct (Fig. 21). Ex tr usomes about 15 pm long, in groups of ca. 5 each, insert ed anteriorly to edge of p eril emma (Fig. 21, 23, 24). Al ways with a V-shaped indentation on dorsal sid e beneath collar region where the att aching membranelles are located (Fig. 27). Cytoplasm colourless and hyaline, often containing nume rous lipid droplets (1---4 pm across), giving the cell a grey ish appearance. Food vacu oles large, several in number, often containing gree n- or yellow -coloured flagellat es. One macronuclear nodule, ovoid to ellipsoi dal w ith large globular nucleoli, centrally position ed; one globular micronucleu s attac hed to macronucleus (Fig. 28, 29). No contractile vacuoles observed. Cilia of membranelles of co llar area ca. 20 pm long, radi at ing outwards; three attaching membranelles abo ut 30 pm in length bending p osteriorly w hen swimmin g (Fig. 24, arrow), o r extending anteriad as shown
OJ
0 0 0.5
OJ
in Fi g. 23 while motionless (Fi g. 23, arro w ). Cells usually crawl on bottom of Petri dish with the help of th e thre e attaching membranelles, leavin g its vent ral side up (Fig. 25). C ircle kinety around edge of perilemma composed of approx imately 50 d iki netid s, with small gap on ventral sid e (Fig. 28-29). Ventral kinety in shallow groove with abo ut 10 dikinetids, extends fro m p osterior re gion almos t to equatorial kinety, usually slightly left of cytosto me (Fig. 28). Girdle of extrusomes distinct, about 4 pm wide, cont inuous on vent ral sid e (Fig. 28, 43). After impregnation, cells mo re bowl-like than ovo id (apical protrusion not recognizable), ofte n width of bod y greater than its len gth , with conspic uous bu ccal field (Fig. 28). Bases of collar membranelles about 10 pm long, each with 3 rows of kinetosomes; posterior to th em on dorsal side, 3 attaching membranelles about 15 pm long, each with only 2 rows of kinetosomes and positioned in shallow grooves, continuous with collar ones, extending posteriorly to equ atorial region of cell. Betw een and parallel to these attaching membranelles, argentophilic fibres alwa ys present (Fig. 30, 31, 46). About 8 bu ccal membranelles, each ca. 5 pm long and thus co nspic uo usly sho rt er th an co llar membranelles; each bu ccal membranelle co nsists of two row s of kin eto somes. Paroral membran e consists of monokinetids and lies alo ng margin of buccal cavit y (Fig. 28). Remarks and comparison with related species. One of th e most interestin g characteristics of thi s
Fig. 32-38. Strombidium sulcatum from life (32-34) and after protargol impregnation (35-38). 32. To show the extrusomes (large arrows) and "primary" platelets which are closely spaced (small arrows). 33. Arrows indicate the irregularly arranged "primary" platelets. 34. To show the groove where the ventral kinety is located (arrow). 35. Ventral view, to show the macronucleus (white arrow), extrusome girdle (small arrows), circle kin ety (double-arrowheads) and the ventral kinety (large arrow). 36,37. Ventral view to show the buccal membranelles(largearrow), newly-built oral primordium (small arrows) and the ventral kinety (white arrow). Note the "absence" of the apical protru sion (arrow in Fig. 36 and double-arrowheads in Fig. 37). 38. To show the extrusome girdle (arrow). Scale bars in 32 = 20 urn; in 35 = 25 pm.
Three Marine Oligotrichous Ciliates from China
+ I
I '\ \
339
" 33
32
// 35
• 36
37
38
340
W. Song, M. Wang and A. Warren
39
40
41
43
42
44
I
45
46
47
Three Marine Oligotrichous Ciliates from China genus/organism is the ongm of the attaching membranelles. Some individuals in early division stages, and at least one cell in the final division phase, were observed (Fig. 31). From these it can be seen that the attaching membranelles derive from the middle portion of the oral primordium, which also generates the other "normal" collar membranelles. It is also confirmed that the attaching membranelles, each of which consists of two rows of kinetosomes, originate as a prolonged part of related collar membranelles. In 1932, Faure-Fremiet described an unique Strombidium, S. calkinsi, which measures about 40 pm in length and has 2 very long (35-40 urn) attaching membranelles (Fig. 22) [16]. It is evidently very closely related to H. paracalkinsi. Since no information is available concerning the infraciliature of S. calkinsi, comparisons can only be made using its morphology in vivo. According to the original description, its body is "irregularly ovoid with a great antero-posterior axis; the hemispherical basal region is bounded by a transversal depression ...; the adoral sinistral zone surrounds the collar with 14 great membranelles...; a conical bundle of intracytoplasmic radiating rods fills the basal part of the body and clearly delineates the annular furrow... " [16]. Strombidium calkinsi is thus very similar to H. paracalkinsi, the main differences being that the former has 2 attaching membranelles that are distinctly separate from the adoral membranelles (vs. 3 in H. paracalkinsi that are continuous with the collar membranelles), and the fact that the manner of attachment when the cell is motionless is dissimilar (Fig. 22, 25). Since FaureFremiet [16] stressed repeatedly that his organism possesses two attaching membranelles, we believe that the number of such organelles should be considered as a reliable and critical character to separate these taxa. Acknowledgements: This work was supported by the "State 973 Research Program" (project number: G1999012001), the National Science Foundation of China (project number: 39970098), and an exquota travel award from the Royal Society of London to the senior author. We would like to thank Zigui Chen and Lei Yanli (College of Fisheries, Ocean University of Qingdao) for help with the photographic development and the collection of some of the samples, respectively.
341
References 1 Agatha S. and Riedel-Lorje J. C. (1997): Morphology, infraciliature, and ecology of halteriids and strombidiids (Ciliophora, Oligotrichea) from coastal brackish water basins. Arch. Protistenkd. 148,445-459. 2 Borror A. C. (1965): New and little known tidal marsh ciliates. Trans. Am. microsc. Soc. 84, 550-565. 3 Borror A. C. (1972): Tidal marsh ciliates (Protozoa): morphology, ecology, systematics. Acta Protozool. 10,29-71. 4 Buddenbrock W. (1920): Beobachtungen uber einige neue oder wenig bekannte marine Infusorien. Arch. Protistenkd. 41, 341-364. 5 Buddenbrock W. (1922): Ober eine neue StrombidiumArt aus Helgoland (Str. clavellinae). Arch. Protistenkd. 45, 129-132. 6 Burger O. (1908): Nuevos estudios sobre Protozoos chilenos del agua dulce. An. Univ. Chile 122, 137-204. 7 Busch W. (1921): Studien uber Ciliaten des Nordatlantischen Ozeans und Schwarzen Meeres. Arch. Protistenk. 42,364-378. 8 Busch W. (1930): Ober marine Strombidium-Arten aus der antarktischen allgemeinen Oststromung. Abh. Mus. Nat. Heimatk. Magdeburg. 4, 83-87. 9 Corliss J. O. (1979): The ciliated Protozoa: characterization, classification and guide to the literature. 2nd ed. Pergamon Press, London. 10 Czapik A. (1976): Strombidium grande Levander. Acta Protozool. 15,273-275. 11 Dragesco J. (1960): Cilie mesopsarnmiques littoraux. Systematique, morphologie, ecologic. Trav.Stn. bioI. Roscoff 12,1-356. 12 Dragesco J. and Dragesco- Kerneis A. (1986): Cilies libres de l'Afrique intertropicale. Faune tropic ale 26,1-559. 13 Entz G. (1884): Ober Infusorien des Golfes von Neapel. Mitt. zool. Stn. Neapel5, 289-444. 14 Faure-Fremiet E. (1911): tudes cytologiques sur quelques Infusoires des marais salants du Croisic. Arch. Anat. Microsc.13,401-479. 15 Faure-Frerniet E. (1924): Contribution a la connaissance des infusoires planktoniques. Bull. bioI. Fr. Belg. (suppl.) 6,1-171. 16 Faure-Frerniet E. (1932): Strombium calkinsi, a new thigmotactic species. BioI. Bull. 57, 201-204. 17 Faurc-Frcmict E. (1950): Ecologic des cilies psammophiles littoraux. Bull. biol. Fr. Belg. 84, 35-75. 18 Faure-Frcrnict E. (1969): Remarques sur la systematique des cilies Oligotrichida. Protistologica 5, 345-352. 19 Faure-Fremiet E. and Ganier M.-C. (1970): Structure fine du Strombidium sulcatum CI. et L. (Ciliata Oligotrichida). Protistologica 6, 207-223.
Fig. 39-47. Strombidium elegans (39-43) and Heterostrombidium paracalkinsi (43-47) after protargol impregnation. 39. Ventral view, to show the prolonged buccal membranelles (arrows). 40. Dorsal view to demonstrate the "extra" kinety fragment in the anterior region (arrow). 41. Ventral view, to show the cell full of diatoms (arrows). 42. Ventral view, to show the "extra" kinety fragment on the ventral side, posterior to the buccal field (arrows). 43, 47. To show the circle kinety (arrow in 47). 44. Dorso-lateral view, to show the macronucleus (arrow) and the attaching membranelies (white arrow). 45. Ventral view to show the buccal apparatus, arrow marks the paroral membrane, while the double arrowheads indicate the buccal membranelles. 46. Right-lateral view, to show the attaching membranelles (white arrow). Scalebars in 41 = 30 urn; in 44 = 35 }lm.
342
W. Song, M. Wang and A. Warren
20 Fenchel T. and Jonsson P.R. (1988): The functional biology of Strombidium sulcatum, a marine oligotrich ciliate (Ciliophora, Oligotrichina). Mar. Ecol. Prog. Ser. 48, 1-15 . 21 Florentin R. (1901): Description de deux infusoires cilies nouveaux des mares salees de Lorraine suivie de quelques considrations. AnnIs. Sci. nat. (Zool.) Paleontol, 12, 343-363. 22 Foissner W. (1994): Progress in taxonomy of planktonic freshwater ciliates. Mar. Microb. Food Webs 8, 9-35. 23 Foissner W., Blatterer H., Berger H . and Kohmann F. (1991): Taxonomische und Okologische Revision der Ciliaten des Saprobiensystems. Band I: Cyrtophorida, Oligotrichida, Hypotrichida, Colpodea, Miinchen: Inforrnationsberichte des Bayer. Landesamtes fr Wasserwirtschaft 1/91,1-478. 24 Kahl A. (1932): Urtiere oder Protozoa I: Wimpertiere oder Ciliata (Infusoria) 3. Spirotricha. Tierwelt Dtl, 25, 399-650. 25 Krainer K.-H. (1991): Contributions to the morphology, infraciliature and ecology of the planktonic ciliates Strombidium pelagicum n. sp., Pelagostrombidium mirabile (Penard, 1916) n. g., n. comb., and Pelagostrombidium fallax (Zacharias, 1896) n. g., n. comb. (Ciliophora, Oligotrichida). Europ. J. Protistol. 27, 60-70. 26 Lei Y., Xu K. and Song W. (1996): Ecological and morphological studies on Strombidium sulcatum, a harmful ciliate during algae cultivation. ]. Fish. Sci. Chin. 3, 39--47 (in Chinese with English summary). 27 Lei Y., Xu K. and Song W. (1999a): Morphological studies on a new ciliate, Heterostrombidium paracalkinesi nov. spec. from mariculture water (Ciliophora, Oligotrichida). Chin.]. Appl. Environ. BioI. 5, 181-184 (in Chinese with English summary). 28 Lei Y., Xu K. and Song W. (1999b): Free living ciliates from marine farming ponds. In: W. Song et al. (ed): Progress in Protozoology, pp. 269-295 (in Chinese). Qingdao Ocean Univ. Press, Qingdao. 29 Levander K. M. (1894): Materialien zur Kenntniss der Wasserfauna in der Umgebung von Helsingfors, mit besonderer Bcriicksichtigung der Meeresfauna 1. Protozoa . Acta Soc. Fauna Flora fenn 12, 1-115. 30 Lynn D. H. and Gilron G. L. (1993): Strombidiid ciliates from coastal waters near Kingston Harbour, Jamaica (Ciliophora, Oligotrichia, Strombidiidae). J. mar. bioI. Ass. U .K. 73, 47-65 . 31 Lynn D. H. and Montagnes D .]. S. (1988): Taxonomic description of some conspicuous species of strobilidiine ciliates (Ciliophora: Choreotrichia) from the Isles of Shoals, Gulf of Maine.]. mar. bioI. Ass. U.K. 68, 639-658. 32 Lynn D. H., Montagnes D . ]. S. and Small E. B. (1988): Taxonomic description of some conspicuous species in the family Strombidiidae (Ciliophora: Oligotrichida) from the Isles of Shoals, Gulf of Maine. ]. mar. bioI. Ass. U. K. 68, 259-276. 33 Maeda M. (1986): An illustrated guide to the species of the families Halteriidae and Strobilidiidae (Oligotrichida, Ciliophora), free swimming protozoa common in the aquatic environment. Bull. Ocean Res. Inst. Univ. Tokyo 21,1-67.
34 Maeda M. and Care y P. G. (1985): An illustrated guide to the species of the families Strombidiidae (Oligotrichida, Ciliophora), free swimming protozoa common in the aquatic environment. Bull. Ocean Res. Inst., Univ, Tokyo 19,1-68. 35 Martin A.]. and Montagnes D. J. S. (1993): Winter ciliates in a British Columbian Fjord: six new species and an analysis of ciliate putative pre y. J. Euk. Microbiol. 40, 535-549. 36 Montagnes D. ]. S. and Lynn D. H. (1991): Taxonomy of choreotrichs, the major marine planktonic ciliates, with emphasis on the aloricate forms. Mar. Microb. Food Webs 5,59-74. 37 Montagnes D.]. S. and Taylor F.]. R. (1994): The salient features of five marine ciliates in the class Spirotrichea (Oligotrichia), with notes on their culturing and behaviour.]. Euk. Microbiol. 41, 569-586. 38 Montagnes D.]. S., Taylor F. J. R. and Lynn D. H. (1990): Strombidium inclinatum n. sp. and a reassessment of Strombidium sulcatum Claparede and Lachmann (Ciliophora).]. Protozool. 37, 318-323. 39 Montagnes D.]. S., Lynn D . H., Stoecker D. K. and Small E. B. (1988): Taxonomic descriptions of one new species and redescription of four species in the family Strombidiidae (Ciliophora, Oligotrichida). ]. Protozool. 35, 189-197. 40 Petz W, Song W. and Wilbert N. (1995): Taxonomy and ecolog y of the ciliate fauna (Protozoa, Ciliophora) in the endopagial and pelagial of the Weddell Sea, Antarctica. Stapfia 40,1-223. 41 Sauerbrey E. (1928): Beobachtungen uber einige neue oder wenig bekannte marine Ciliaten. Arch. Protistenkd. 62,355--407. 42 Song W. (1996): Morphogenetic studies on Strombidium sulcatum (Ciliophora, Oligotrichida). Nat. Sci. Pro gr. China.6,16-25. 43 Song W. (1999): Infraciliature of oligotrichous ciliates at generic level. In: W. Song et al. (ed): Progress in Protozoology, pp. 155-176 (in Chinese). Qingdao Ocean Univ. Press, Qingdao. 44 Song W. and Bradbury P. C. (1998): Studies on some new and rare reported marine planktonic ciliates (Ciliophora: Oligotricha) from coastal waters in North China. J. mar. bioI. Ass. U.K. 78, 767-794. 45 Song Wand Packroff G. (1997): Taxonomische Untersuchungen an marin en Ciliaten aus China mit Beschreibungen von 2 neuen Arten, Strombidium globosaneum nov. spec. und Strombidium piatum nov. spec. (Protozoa, Ciliophora). Arch. Protistenkd. 147,331-360. 46 Song W., Wilbert N. and Warren A. (1999): Three new entocommensal ciliates from digestive tract of sea urchins of the Weddell Sea, Antarctica (Protozoa, Ciliophora). Polar BioI. 22, 232-240. 47 Wang C. C. (1934): Notes on the marine infusoria of Amo y. Mar. BioI. Ass. China, Annual Rep. 3, 50-70. 48 Wilbert N. (1975): Eine verbesserte Technik der Protargolimpragnation fur Ciliaten. Mikrokosmos 64,171-179. 49 Wilbert N . (1986): Beitrag zur Morphologic und Okologie einiger planktischer Ciliaten aus dem Poppelsdorfer Weiher in Bonn (BRD). Arch. Protistenkd. 131,59-69.