The World of Protozoa, Rotifera, Nematoda and Oligochaeta
Dysteria
Dysteria Huxley, 1857 (ref. ID; 2013)
From Dr. Inaki
Class Kinetofragminophora: Subclass Hypostomata: Order Cyrtophorida: Suborder Dysteriina (ref. ID; 2013)
Class Kinetofragminophora de Puytorac et al., 1974: Order Cyrtophorida Faure-Fremiet, 1956 (ref. ID; 4893)
Synonym Aegyria Claparede & Lachmann (ref. ID; 1618); Cypridium Kent (ref. ID; 1618); Ervilia Dujardin (ref. ID; 1618); Iduna Claparede & Lachmann (ref. ID; 1618)
[ref. ID; 2013]
Body outline shape approximately oval with the dorsal surface being strongly arched and often longitudinally ribbed, ventral surface flattened. There is a posterior cytoplasmic spine from which a thread may be secreted for attachment to the substratum. Somatic ciliation greatly reduced and restricted to ventral surface alone. The right ciliary field consists of 4 to 6 kineties of which 2 to 4 extend beyond the oral aperture and curve around the body apex. The left field of kineties is in two parts as is found in Trochilia and not as a continuous field as in Orthotrochilia and Trochilioides. One part consists of a few rows lying equatorially, close to and parallel with the right field. The other part of the left field lies in front of the oral aperture situated between the pre-oral and circumoral ciliary rows. There are only two elements in the cytopharyngeal basket, the teeth of which are complex in structure but never sharp and needle-like. The macronucleus is large, ovoid and centrally placed. There are 2 contractile vacuoles.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)
[ref. ID; 4943]
Type species; Dysteria armata Huxley, 1857 (ref. ID; 4943)
Dysteria derouxi Gong & Song, 2004 (ref. ID; 4943 original paper)
Diagnosis
Marine Dysteria with a rectangular body shape, about 100 x 40 um in vivo; 8 ventral kineties in right field, of which the right-most 3 extend dorso-apically; 6-9 short kineties in left equatorial field; and two ventral contractile vacuoles. (ref. ID; 4943)
Descriptions
Size range 75-110x30-50 um in vivo, usually ca. 100x40 um body bilaterally flattened about 1:3. When observed from the side, cells nearly rectangular in outline, with the ventral side straight and dorsal slightly convex. Anterior margin usually transverse truncate, posterior region somewhat narrowed. Right plate arched and slightly wider than the flattened left plate. No conspicuous grooves or ridges on the cell surface. As in congeners, ciliary rows restricted to the antero-ventral groove between the two plates. Podite about 12 um in length, distal end pointed or blunt, emerges from the left posterior ventral side. Cytoplasm colorless to grayish, usually containing many food vacuoles (ca. 5 um in diameter) and several ingested diatoms ca. 10-30 um long. Cytostome in anterior 1/5-1/6 of cell and ventrally located. Cytopharynx typical of genus, diagonally oriented. Two ventral contractile vacuoles, 6-12 um in diameter, usually one in anterior third and the other in the posterior third of the body. Macronucleus (Ma) elongate, conspicuously large, about 36x16 um in vivo and ca. 40x14 um after protargol impregnation, centrally positioned, characteristically heteromerous; micronucleus not detected. Cilia about 10 um long. Movement moderately rapid, usually "standing" on substrate with podite slowly extending back and forth while the organism crawls forward. (ref. ID; 4943)
Infraciliature: When viewed from side, right field occupied by eight ventral, kineties (VK), among which the right-most three extend anteriorly to dorsal margin: the outer two almost equally long, while the inner one is slightly shortened. The other five ventral kineties end anteriorly slightly above or below the level of cytostome. Right-most ventral kinety consisting of ca. 200 basal bodies. All eight ventral kineties terminate posteriorly almost at the same level and are usually composed of groups of 4-5 basal bodies. One hook-like terminal fragment (Tf) comprising 10-19 antero-dorsally positioned basal bodies. Equatorial fragment composed of ca. 16 basal bodies. Six to nine left kineties (LK) with densely arranged basal bodies, equatorially positioned, close to ventral kineties. One argyrophilic glandule-like structure, sausage- or U-shaped, with each arm about 8 um long, subterminally present near the ventral margin; seven to eleven (mean 9) kinetosome-like granules invariably present near the base of the podite. Oral structures as in congeners: they consist of two parallel circumoral kineties (Co) and a single-rowed preoral kinety (Pr), both of which are composed of dikinetids and positioned anterior to cytostome; three oblique left frontal kineties (Lf) composed of monokinetids. Cytopharynx extending to about posterior 1/4 of cell, composed of fibrous membranes and two complex cytopharyngeal rods (CR), each with a triangular tooth. (ref. ID; 4943)
Comparison with related species
Morphologically, D. procera Kahl, 1931 should be closely related to D. derouxi; nevertheless, it differs from D. derouxi in having fewer (3 vs. 8) ventral kineties (Gong & Song 2003). Another similar form, D. monostyla (Ehrenberg, 1838), Kahl, 1931 has a similar size (60-110 um) and body shape (Kahl 1931; Dragesco & Dragesco-Kerneis 1986). According to the redescription by Gong et al. (2002), however, it has only five ventral kineties. (vs. 8 in D. derouxi). Considering the body size and infraciliature pattern, three species, i.e. D. pusilla (Claparede & Lachmann, 1859), D. cristata (Gourret & Roeser, 1888) Kahl, 1931 and D. calkinsi (Calkins, 1902) Kahl, 1931 can be clearly separated from D. derouxi in having much smaller size (15-50 vs. 75-110 um) and fewer (5 or lower vs. 8 in D. derouxi) ventral kineties. D. magna Gong & Song, 2003 also has, like D. derouxi, eight ventral kineties, but differs from that species in: (1) different body shape, i.e. more oval than elongate (length to width about 3:2 vs. 5:2); (2) being (bilaterally) extremely compressed (1:6-8 vs. 1:3) and (3) having only two (vs. three) ventral kineties extending dorso-apically. With reference to the somatic ciliature, the Antarctic form D. parovalis Wilbert & Song, 2004 is also similar to D. derouxi. The former, however, can be recognized by: (1) smaller size (50-80x40-60 vs. 75-110x30-50 um); (2) 9 ventral kineties (vs. 8) and (3) relatively smaller (25x15 vs. 40x14 um) macronucleus (Wilbert & Song, 2004). D. antarctica (Gong et al., 2002) was isolated from the Antarctic area and was originally described by Petz et al. (1995) under the name of D. monostyla. Compared with our new species, it can be separated by body size (145x65 vs. 75-110x30-50 um) and number (5 vs. 8) of ventral kineties (Gong et al., 2002). D. armata Huxley, 1857, the type species of the genus, has, according to Kahl (1931), a very similar body length (80-120 um) to D. derouxi. These two taxa, however, can be separated by body shape (oval vs. rectangular) and number (6 vs. 8) of ventral kineties (Faure-Fremiet, 1965). The cell size of D. ovalis (Gourret & Roeser, 1886) Kahl, 1931 is unknown. Nevertheless, it can be distinguished from D. derouxi in terms of body shape (oval vs. rectangular) and number (4 vs. 8) of ventral kineties (Faure-Fremiet, 1965). D. brasiliensis Faria et al., 1922 can be clearly distinguished in terms of the presence of the caudal spine and the conspicuously lower number (5 vs. 8) of ventral kineties (Song & Packroff 1997). In 1966, Dragesco described two new species from Roscoff, France: D. spinifera and D. meridionalis, both of which are about 100 um long; no infraciliature data were given. However, D. spinifera exhibits consistently different features in vivo, e.g. one apical and one caudal spine on the dorsal side (vs. without spines in D. derouxi), and a single contractile vacuole (vs. two contractile vacuoles in D. derouxi). D. meridionalis can be separated from D. derouxi by having an apically (vs. ventrally) located cytostome and a conspicuous crease (absent in D. derouxi) along its dorsal margin. The body shape of D. derouxi also resembles that of D. aculeata Claparede & Lachmann, 1859 and D. marioni (Gourret & Roeser, 1886) Kahl, 1931. Unfortunately, neither the size nor the infraciliature of these two organisms have been described. However, D. derouxi has no dorsal spines (vs. present) and conspicuous elongate body shape (length:width 2.5:1 vs. 2:1), which helps to distinguish if from them. Lei et al. (1999) misidentified a morphotype under the name D. ovalis (Gourret & Roeser, 1886) Ozaki & Yagiu, 1943, which was collected from the same area as our new species. It is characterized by: body size 90-100x42-45 um in vivo, rectangular or ellipsoid in shape outline, eight ventral kineties and three ciliary rows extending dorso-apically, two ventrally located contractile vacuoles and macronucleus about 39x13 um in size after protargol impregnation (Lei et al. 1999). Hence, it corresponds perfectly to D. derouxi and could very likely be conspecific with the latter. (ref. ID; 4943)
Etymology
This new species is dedicated to Dr. Gilbert Deroux, the French protozoologist, to show our respect for his great contributions on cyrtophorid ciliates. (ref. ID; 4943)
Type location
Clean coastal water of the Yellow Sea near Qingdao, with the following ecological features: salinity about 30 0/00; water temperature 11 degrees C; pH 7.1; transparency 2.2 m; soluble active phosphorus 0.76 mg/l; ammonia-nitrogen 0.07 mg/l; nitrate-nitrogen 0.10 mg/l; and nitrite-nitrogen 0.06 mg/l. (ref. ID; 4943)
Type specimens
One holotype slide of protargol impregnated specimens is deposited in the Natural History Museum, London, UK with registration number 2003:6:12:2. Two paratypes are deposited in the Laboratory of Protozoology, Ocean University of Qingdao, China (number HD-0012070201, HD-0012070202). (ref. ID; 4943)
Dysteria magna Gong & Song, 2003 (ref. ID; 4922 original paper, 4943)
Diagnosis
Large and highly flattened marine Dysteria about 150x100 um in vivo; body shape broadly rectangular with two ventrally located contractile vacuoles; 8 ventral kineties in right field with right-most two extending anteriorly to dorsal side; c. 7 short rows of kineties in left equatorial field. (ref. ID; 4922)
Descriptions
Cell size (in 4 individuals) about 150-160x100 um in vivo, body extremely bilaterally compressed about 1:6-8. From side view, body broadly rectangular, length: width about 3:2, both anterior and posterior ends evenly rounded; ventral side almost straight and dorsal side slightly convex. Unlike many of its congeners, both left and right plates flattened, without any groove or ridge and generally transparent when observed in life. Cilia in most parts of cell about 15 um in length, while longer (ca. 20-25 um) and somewhat stiff near buccal area. Podite relatively small, about 20x10 um in vivo, protruding only slightly from ventral margin. Cytoplasm colourless to grayish, usually with many differently-sized food vacuoles and numerous granules, which render the cell sometimes more or less opaque. The canal-like vacuoles along posterior and dorsal margins. Cytostome as in its congeners, located antero-ventrally, beneath which there is a dominant cytopharynx with teeth-complex extending postero-dorsally. Two large contractile vacuoles (CV), 10-20 um in diameter (usually formed by converging of several small vacuoles). Movement very slow, mostly lying (rather than "standing") and gliding on substrate. (ref. ID; 4922)
Infraciliature: Cell size about 135-145x95 um after fixation. Constantly 8 ventral kineties (VK) in right field, of which the right-most two are almost equal in length with each row consisting of about 260 basal bodies, and both extend anteriorly beyond the cytostome and bend to the dorsal side. Anterior ends of all the other 6 rows shorted progressively with the left-most three shortened at both ends. Rather uniquelly, basal bodies in anterior portion of the left-most 4 kineties irregularly and loosely distributed, while in other regions, kineties consisting, as usual, of fragments each with about 4 basal bodies. About 7 short rows with densely packed kinetosomes, positioned in left equatorial area. Terminal fragment (Tf) 2- or 3-rowed, comprising ca. 40 basal bodies in total. Equatorial fragment (Ef) normally present, consisting of 15-47 basal bodies. (ref. ID; 4922)
Macronucleus (Ma): Ellipsoidal, ca. 50x30 um after protargol impregnation, centrally located, characteristically heteromerous; micronucleus not observed. Often about 20 argentophilic granules (unciliated kinetosomes?) near the base of podite. Arrangement of oral ciliature typical of genus: both the double-rowed circumoral kineties (Co) and the single-rowed preoral kinety (Pr) with dikinetids, and the three-rowed left frontal kineties (Lf) with monokinetids. Cytopharynx composed of two complex pharyngeal rods and associated fibrous membranes, extends posteriorly to near posterior end of cell. (ref. ID; 4922)
Comparison
This new species is recognized by the huge size, broad rectangular body shape, the canal-like vacuoles on dorsal as well as caudal margin and the presence of 8 ventral ciliary rows of somatic kineties in the right field. Considering species with large cell size and from a marine habitat, only two species, namely D. brasiliensis and D. antarctica, are reported to exceed 100 um in length. Compared with D. magna, D. brasiliensis can be clearly recognized by its conspicuously more slender body shapes, presence of the dorsal spine (vs. absence in D. magna) and lower number of ventral kineties in right field (5 vs. 8 in D. magna). Another large form, Dysteria antarctica Gong et al., 2002 is characterized by the slender body shape (width:length ca. 1:2) and having consistently fewer ventral kineties in the right field (5 vs. 8 in D. magna)
Type location
A clean marine tank for abalone-farming in Qingdao, China. (ref. ID; 4922)
Slender marine Dysteria, 80-110x25-40 um in vivo; 3 ventral kineties in right field, of which the right-most two extend apically to the dorsal margin and the left one is highly shortened; ca. 6-9 short rows of kinetosomes in left equatorial field; two ventrally located contractile vacuoles. (ref. ID; 4922)
Descriptions
Size in vivo about 80-110x25-40 um, body shape consistent and bilaterally flattened about 1:4. From side view, body elongate and slender in outline shape (length: width about 2.5-3:1), anterior margin slightly truncated and posteriorly more or less tapering. Ventral side straight, and dorsal side slightly convex. When viewed dorsoventrally, cells always bend to the left. Podite (P) relatively small and slender, ca. 10 um in length, protruding subcaudally from ventral groove. Cilia 8-10 um long. As in its congeners, ciliary rows mostly restricted to ventral groove between left and right plates. No conspicuous grooves or ridges on lateral plates. Cytoplasm colourless to grayish, with several dark food vacuoles (4-5 um in diameter) and shining globular crystals (2-4 um across). Cytostome in anterior 1/8 of cell length and ventrally located. Two contractile vacuoles, about 4 um in diameters, ventrally located, one in anterior third the other in posterior third of body. Movement slow, crawling on substrate, occasionally swimming in water for several seconds and then returning to substrate. (ref. ID; 4922)
Infraciliature: Right field occupied by 3 ventral kineties (VK), among which the right-most 2 are approximately equal in length (each row consisting of 140-160 basal bodies), extend anteriorly beyond the level of cytostome and bend to the dorsal side. Left one "unusually' shortened, with anterior end terminating at about posterior fourth of body length. Most portions of the 3 ventral kineties conspicuously fragmented, each group with about 4 basal bodies. Terminal fragment (Tf) comprising 6-10 basal bodies, antero-dorsally positioned. Single-rowed equatorial fragment (Ef) at extreme right of equatorial field, consisting of c. 10 (3-15) basal bodies. In left field, 6-9 genus-typical short rows with densely packed kinetosomes, positioned close to ventral kineties. (ref. ID; 4922)
Macronucleus: Ellipsoidal and characteristically heteromerous, 24-36x8-12 um in size after protargol impregnation, positioned in mid-body. Micronucleus not observed. One argentophilic glandule-like structure subcaudally positioned, 5 um in diameter; seven to nine kinetosomes-like granules sometimes present near the base of podite. Arrangement of oral kineties typical of genus: one double-rowed preoral kinety (Pr) positioned dorsally to cytostome, three single-rowed left frontal kineties (Lf) and 2 circumoral kineties (Co). Cytopharynx slender and straight, longitudinally oriented, with two pharyngeal rods and associated fibrous membranes, extending posteriorly to about 80% of cell length. (ref. ID; 4922)
Remarks and comparison
As confirmed by recent studies, the pattern of infraciliature in most cyrtophorid is highly stable, especially these in small taxa, and is considered hence as one of the most significant criteria for species separation. Dysteria procera was originally reported from the North Sea, Germany (Kahl 1931) with a brief description concerning only the morphology of live cells. Since then, no redescription of this species remains unknown. However, we are convinced that the identification of our organism is correct because it resembles the original description in all known aspects, e.g. body shape, size, number and position of contractile vacuoles, as well as the marine habitat. Till now, a total of 10 Dysteria species have been described using silver staining techniques; these include: D. armata, D. monostyla, D. brasiliensis, D. calkinsi, D. parovalis, D. antarctica and D. ovalis. Compared with these seven taxa, D. procera can be recognized by fewer ventral kineties (3 vs. 4 or more) and other combined morphological characters, e.g. body shape, size and ciliature patterns. Very recently, Gong et al. have studied another two species, Dysteria cristata (Gourret and Roeser, 1888) Kahl, 1931 and D. pusilla (Claparede and Lachmann, 1859), and demonstrated that both organisms possess 3 ventral kineties (Gong et al. 2002, 2003). D. cristata differs from D. procera in its smaller body size (40-50x25-30 vs. 80-110x25-40 um), asymmetrically oval body shape (vs. elongate and slender) and the position of the left-most ventral kinety (terminated anteriorly near cytostome vs. below the level of mid-body). The tiny species D. pusilla can be distinguished from D. procera also by its much smaller body size (15-30x10-20 vs. 80-110x25-40 um). The position of the left-most ventral kinety (terminated anteriorly near cytostome vs. below mid-body), and the possession of three contractile vacuoles (vs. 2 in D. procera). With reference to the cell size and habitat, at least 4 other nominal forms: D. spinifera, D. proraefrons, D. pectinata and D. meridionalis, whose infraciliature remains unknown, should be compared with D. procera. Dyseria spinifera Dragesco, 1966 can be separated from D. procera by the two dominant dorsal spines (vs. absence in the latter) and the number of contractile vacuoles (single vs. two) (Dragesco 1966). With its conspicuously slender body shape, Dysteria procera can be clearly distinguished from the other 3 morphotypes, i.e. remarkably rectangular in D. meridionalis Dragesco, 1966; oval in D. pectinata (Nowlin, 1913) Kahl, 1931 and asymmetrically oval in D. proraefrons James-Clark, 1866. (ref. ID; 4922)
