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Protistology 4 (2), 121-127 (2005)
Protistology
First records of Trichodina japonica Imai, Miyazaki et Nomura 1991 and Trichodina mutabilis Kazubski et Migala 1968 (Ciliophora, Trichodinidae) from Indian fishes
Amlan Kumar Mitra and Probir K. Bandyopadhyay
Parasitology Laboratory, Department of Zoology, University of Kalyani, Kalyani, West Bengal, India
Summary
An icthyoparasitological survey in search of the trichodinid ciliophorans from the genus Trichodina Ehrenberg, 1838 has revealed the occurrence of two previously described species for the first time in India. They are T. japonica Imai, Miyazaki and Nomura, 1991 from gills of an euryhaline fish, Lates calcarifer (Bloch) and T. mutabilis Kazubski and Migala, 1968 from gills of a freshwater fish Nandus nandus (Hamilton). This paper provides taxonomic descriptions of these two species based on the light and scanning electron microscopic observations along with new host and locality records and prevalence rates.
Key words: biodiversity, trichodinids, ectoparasites, Trichodina japonica, Trichodina mutabilis, fish, India
Introduction
One of the largest and most widely distributed ciliophoran genera is Trichodina Ehrenberg, 1838, the representatives of which are parasites or symbionts of aquatic invertebrate and vertebrate hosts (Van As and Basson 1989). Work on this particular group in India got momentum in 1980, although Annandale (1912) paved the way more than nine decades ago. Studies on the biodiversity of the trichodinids in various water bodies ofWest Bengal have revealed the presence of one marine species, Trichodina japonica Imai, Miyazaki and N omura, 1991 from euryhaline water of the Matla River
of the district of South 24 Parganas and one freshwater species, T. mutabilis Kazubski and Migala, 1968 from the Churni River of the district of Nadia, for the first time in Indian fishes. Indian population of T. japonica exhibit some morphological variability as compared with the other two populations of this species reported so far from Japan and China. The present paper also presents a scanning electron microscopic description of T. mutabilis, providing some additional morphological features of the species. This paper deals with the taxonomic descriptions of these two species based on the light and scanning electron microscopy, along with the new host and locality records and prevalence rates.
© 2005 by Russia, Protistology
Material and Methods
The Matla is a short but very rapid river, passing through the district ofSouth 24 Parganas (21.5°N, 89°E; Fig. 1). It flows directly into the Bay of Bengal and experiences high and low tides. On the other hand, the Churni river is one of the many tributaries of the Ganges and flows through the district of Nadia in West Bengal (23°E, 88.5°W, Fig. 1). It is a small and docile river and provides a fresh water environment. Samplings were carried out to collect host fishes from the rivers Matla and Churni. Host fishes were brought alive to the laboratory, and gill and skin smears were made on grease free slides. Slides containing trichodinid ciliates were impregnated using Klein's dry silver impregnation technique (Klein, 1958). Preparations were examined under an Olympus phase contrast microscope at + 1000 magnifications with an oil immersion lens. Photographs and measurements were taken with an Olympus camera and a calibrated ocular scale fitted with the microscope, respectively. Measurements are in micrometers and follow the uniform specific characteristics as proposed by Lom (1958), Wellborn (1967) and Arthur and Lom (1984). In each case minimum and maximum values are given, followed in parentheses by arithmetic mean, standard deviation and number of specimens observed. For statistical analysis, morphometric measurements of 20 specimens for both species were considered. In the case of denticles and radial pins, the mode is given instead of the arithmetic mean. The span of the denticle is measured from the tip of the blade to the tip of the ray. Body diameter is measured as the adhesive disc plus border membrane. The description of denticle elements follows the guidelines of Van As and Basson (1989). Sequence and method of the description of denticle elements follows the recommendations of Van As and Basson (1992).
For SEM studies specimens were fixed in 4% buffered glutaraldehyde, washed in phosphate buffer, dehydrated in ascending concentrations of ethanol, transferred to amyl acetate and critical point dried using a Hitachi HP-2 critical point apparatus. Sputter coating was done with gold in an IB-2 coater. Observations were carried out with a Hitachi S-530 (Japan) Scanning Electron Microscope operating at 15 KV.
Results
Two species of ciliates belonging to the genus Trichodina Ehrenberg, 1838 were obtained from the fishes collected. They are Trichodina japonica Imai, Miyazaki and Nomura, 1991 from gills of Lates calcarifer (Bloch) and T. mutabilis Kazubski and Migala, 1968 from gills of Nandus nandus (Hamilton). Descriptions are given below.
Fig. 1. A map of the southern part of West Bengal, showing the Churni and the Matla rivers and sampling localities.
Trichodina japonica Imai, Miyazaki and Nomura, 1991 (Figs. 2-3, 8; Table 1).
Small-sized ciliate with a disc-shaped body. Whitish border membrane surrounding adhesive disc. Central area impregnating dark. Denticles axe-shaped. Blade broad distally, filling most area between y-axes. Distal surface of blade short, truncated. Anterior margin of blade slightly angular, forming prominent apex. Anterior blade apophysis absent. Tangent point like straight line situated well below distal point of distal surface. Posterior margin forming deep semilunar curve. Blade joining central part at base of ray with broad connection. Central part short, triangular. Tip of central part rounded or sharply pointed, extends halfway towards y-1 axis, fits loosely preceding denticle. Section of central part above and below x-axis similar in shape. Well-developed straight ray with bluntly rounded tip, directed towards y+1 axis.
Taxonomic summary Host: Lates calcarifer (Bloch)
Host family: Centropomidae
Locality: Canning (21.5°N, 89°E), South 24 Parganas
Location: Gills
Prevalence: 61/ 195 (31.3 %)
Remarks: T. japonica was originally described by Imai et al. (1991) from the gills of cultured Japanese eel, Anguilla japonica. This species was subsequently redescribed by Xu et al. (1999) from two marine fishes of Chaina, i.e., Lateolabrax japonicus and Chrysophrys major. Indian population of T. japonica obtained from the coast of Bay of Bengal exhibits a slightly lower range ofbody dimensions than those reported from Japan and China. Specimens described in the present paper have some variability in comparison to the other two foreign
Figs 2-3. Micrographs of silver nitrate impregnated adhesive discs of Trichodina japonica Imai, Miyazaki and Nomura, 1991 from the gills of Lates calcarifer (Bloch). Scale bars = 20^m.
populations when denticle structures and host specificity are considered. Imai et al. (1991) observed in specimens obtained from cultured eels several small dark granules in the central area of the denticulate ring. In our study, we did not observe the presence of any such granules in the central area of the denticulate ring that might be due to deficiency in silver nitrate impregnation. Another significant difference is in the direction of the rays of the blade in the Japanese/Chinese and Indian populations of T. japonica. In case of the Japanese and Chinese populations, the tips of the rays are directed towards
the geometric centre of the adhesive disc, but in all the specimens obtained from the Indian estuarine fish Lates calcarifer, the rays are directed consistently towards y+1 axis. T. japonica obtained from a new host and locality along the coast of the Bay of Bengal is the first report of this species from India. Morphometric comparisons, geographical distributions, host ranges of Trichodina japonica Imai, Miyazaki and Nomura, 1991 from various parts of the world are summarized in Table 1. Observation on the distribution of T. japonica reported from coastal areas of three Asian countries from three diffe-
Table 1. Morphometric comparison of Trichodina japonica Imai, Miyazaki and Nomura, 1991 obtained in the present study with the data of other authors.
Host Lates calcarifer Anguilla japonica Lateolabrax japonicus Chrysophrys major
Locality India Japan China
Location gills gills gills
References present study Imai et al., 1991 Xu et al., 1999
Diameter of body adhesive disc Dimension of denticulate ring central area Width of border membrane 20.9-25.4 (22.4± 1.2, 20) 16.8-21.4 (18.5± 1.1, 20) 9.6-12.7 (11.3± 1.5, 20) 2.5-6.1 (4.1± 0.8, 20) 1.5-2.0 (1.9± 0.1, 20) 27.0-41.0 (33.6± 3.7) 18.0-25.0 (21.7± 2.0) 9.0-15.0 (11.9± 1.6) 1.5-3.0 (2.3± 0.6) 22.0-29.0 (24.3± 1.9, 16) 17.0-22.0 (20.3± 1.7, 16) 8.0-13.0 (10.3± 1.2, 16) 2.0-3.0 (2.2± 0.3, 16)
Number of denticles radial pins/denticle Dimension of denticle span length Dimension of denticle components length of ray length of blade width of central part Adoral ciliary spiral 17-21 (18, 20) 5-7 (6, 20) 5.1-6.6 (5.5± 0.4, 20) 2.5-3.5 (3.1± 0.2, 20) 2.0-3.1 (2.2± 0.3, 20) 2.0-2.5 (2.1± 0.2, 20) 1.1-1.2 (1.1± 0.1, 20) 360-390° 18-23 (20.7± 1.1) 6 4.0-7.5 (6.5± 0.8) 3.5-5.0 (4.3± 0.5) 1.0-3.5 (2.8± 0.5) 2.0-3.0 (2.5± 0.4) 1.0-1.5 (1.1± 0.2) 390° 18-21 (19.2± 0.8, 16) 6-7 (16) 4.0-6.0 (5.2± 0.7, 16) 2.5-4.0 (3.1± 0.4, 16) 1.5-3.5 (2.6± 0.6, 16) 1.5-2.5 (1.9± 0.3, 16) 1.0-1.5 (1.1± 0.2, 16) 390°
rent hosts agree with Lom (1958) and Lom and Hoffman (1964). T. japonica seems to be an Asian marine trichodinid species, because up to date this species has only been reported from the coastal areas of Asia.
Trichodina mutabilis Kazubski and Migala, 1968 (Figs. 4-7, 9; Table 2).
Medium sized trichodinid with broad blade. Distal surface of blade flat, like straight line and running parallel to border membrane of adhesive disc. Tangent point blunt, situated on same level or slightly lower than distal margin. Anterior margin almost parallel to posterior margin. Blade thickened along posterior margin (Fig. 7). Apex prominent in some specimens. Apex extends or even touches y+1 axis. Blade apophysis prominent (Fig. 7). Semilunar curve formed by posterior margin of blade shallow, its deepest point situated at same level as apex. Blade connection thick. Central part moderately sized, almost triangular and extends more than halfway to y-1 axis. Posterior portion of central part very thin. Denticles tightly locked. Presence of ray apophysis well visible on SEM picture. Thickness of rays same along entire length. Tip of ray rounded. Rays straight and directed towards y+1 axis. Taxonomic summary Host: Nandus nandus (Hamilton)
Host family: Nandidae Locality: Ranaghat, W. Bengal, India Location: Gills Prevalence: 93/446 (20.9 %)
Reference material: CH-5/2001 is in the collection of authors.
Remarks: Kazubski and Migala (1968) first described T. mutabilis from the breeding carp, Cyprinus carpio, from Poland. Since then this species has been recorded mainly on the gills of cyprinid fishes, from various places in Eastern Europe, the former USSR, South Africa, Israel and Taiwan (Kazubski and Migala, 1968; Ivanova, 1970; Migala, 1970, 1971; Kashkovsky, 1974; Basson and Van As, 1994).
T. mutabulis described in this paper represents the lowest range ofbody dimensions reported so far (Table 2) and is also the first record of this species from India from a non cyprinid host fish Nandus nandus (Hamilton) belonging to the family Nandidae. This finding is important because it reveals that T. mutabilis also prefers a non-cyprinid fish as its host and throws new light on the biodiversity and host preference of the species. The populations obtained from Nandus nandus show significant resemblance in denticle structure with those of winter specimens reported by Kazubski and Migala (1968) obtained from Cyprinus carpio. Scanning electron microscopic study reveals that the blades of the denticles are thickened posteriorly. Presence of the blade and the ray apophysis can be clearly seen on the scanning electron micrographs, but is not well discernible at light microscopic level. The posterior portion of the central part situated just below the x-axis is very thin and rounded, and is clearly visible on the SEM picture (Fig. 7). Morphometric comparisons, geographical distributions, host ranges of Trichodina mutabilis Kazubski and Migala, 1968 from various parts of the world are summarized in Table 2.
Table 2. Morphometric comparison of Trichodina mutabilis Kazubski and Migala, 1968 obtained in the present study with the data of other authors.
Host Nandusnansus Cyprinus carpio Cyprinus carpio Carassius auratus Cyprinus carpio H. molitrix
Locality India Poland Czechoslovakia Taiwan
Location gills gills skin gills
References present study Kazubski and Migala, 1968 Lom, 1970 Basson and Van As, 1994
Diameter of
body 40.1-51.0 (46.1±3.4, 20) 65.5-105.0 (84.8) 78 (69-97) 57.0-70.0 (63.4±4.2, 13)
adhesive disc 31.6-42.8 (37.7±3.5, 20) 52.0-70.7 (61.9) 57(49-61) 46.0-58.0 (52.4±4.1, 13)
Dimension of
denticulate ring 19.3-29.4 (23.4±2.7, 20) 31.2-45.8 (37.9) 38(32-41) 29.0-37.5 (32.6±2.5, 13)
central area 4.5-13.2 (8.4±2.3, 20) — — —
Width of border membrane 4.0-6.6 (4.5±0.6, 20) 6.0 6-7 4.5-6.5 (5.6±0.6, 13)
Number of
denticles 22-28 (24, 20) 26-30 (29.15) 28 (26-30) 23-29 (27, 13)
radial pins/denticle 6-9 (7, 20) 9-10 9-10 9-11 (10)
Dimension of denticle
span 11.6-14.4 (12.6±0.8, 20) — — 15.0-18.0 (16.4±0.8, 13)
length 4.2-7.1 (5.3± 0.6, 20) — 9 7.0-8.0 (7.4±0.4, 13)
Dimension of denticle components
length of ray 4.5-7.1 (5.6±0.6, 20) — 8 6.5-8.0 (7.5±0.5, 13)
length of blade 4.4-6.6 (5.3±0.5, 20) — 7 6.0-7.0 (6.5±0.4, 13)
width of central part 1.2-2.0 (1.7± 0.2, 20) 2-3.3 2.5 1.5-2.5 (1.9±0.3, 13)
Adoral ciliary spiral 400-410° 400° — 400°
Figs 4-7. Micrographs of Trichodina mutabilis Kazubski and Migala, 1968 from the gills of Nandus nandus (Hamilton). 4 - Silver nitrate impregnated adhesive discs; 5-7 - scanning electron micrographs: 5 - adoral view, 6 - aboral view of a denticulate ring, 7 - aboral view of a section of a broken denticulate ring. Abbreviations: acs - origin of adoral ciliary spiral, bm - border membrane, cp - central part, ba -blade apophysis, ra - ray apophysis. Scale bars: 4-6 - 20^m, 7 - 5 ^m.
Discussion
In India, the emphasis has always been on describing new species, and as a result 10 new species belonging to the genus Trichodina have been described so far (Asmat and Haldar, 1998; Asmat, 2000a, 2001a, 2001b, 2001c, 2002a, 2002c; Mitra and Haldar, 2004). Interestingly, the reports on the occurrence of known trichodinid species in India are much less numerous than could be expected. Only four previously known trichodinids, i.e. Trichodina pediculus (Annandale, 1912; Hagargi and Amoji, 1979), T. nigra (Mukherjee and Haldar, 1982; Saha et al., 1995; Asmat, 2002a), T. reticulata (Mishra and Das, 1993) and T. acuta (Asmat, 2000b) have so far been reported from India. Up to date, more than 220
Figs 8-9. Diagrammatic drawings of the denticles of trichodinids. 8 - Trichodina japonica from the gills of Lates calcarifer (Bloch); 9 - T. mutabilis from the gills of Nandus nandus (Hamilton).
species of the genus Trichodina have been reported from various corners of the world. So, the list of only four known species of the trichodinid ciliophorans from a biodiversity hot spot country like India is obviously far from complete. Repeated investigations should be carried out in India to explore both new and previously described trichodinid species and to provide detailed information on their geographical distribution, host range and morphological variability using modern tools and techniques.
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Address for correspondence: Amlan Kumar Mitra. Parasitology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India. E-mail: amlan_mitra@hotmail.com
Editorial responsibility: Sergei Fokin
