Rotifera: India

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Faunal Diversity In India: Rotifera

This is an extract from FAUNAL DIVERSITY IN INDIA Edited by J. R. B. Alfred A. K. Das A. K. Sanyal. ENVIS Centre, Zoological Survey of India, Calcutta. 1998 ( J. R. B. Alfred was Director, Zoological Survey of India)

Rotifera

Introduction

Phylum Rotifera represents a small group of animal kingdom which is, however, well known for its very distinct qualitative and quantitative significance in freshwater biotopes. The rotifers are pseudocoelomate micro¬organisms and their body size usually ranges between 40-250 ~ but certain larger species (size upto 2.0 mm) can, however, be observed with unaided human eye as small dots, sacs or rods. They depict intricate structure and endless profusion of body forms which, in turn, are morphologically well adapted to their living habits as well as closely associated with their habitats. Besides, a number of species exhibit interesting ecotypic and cyclomorphic variations and have, therefore, resulted in frequent allocation of infraspecific categories by various workers. The rotifer descriptions in the literature usually refer to the commonly occurring parthenogenetic females. The males, on the other hand, are rare, diminutive and shortlived.

The rotifers are commonly termed as 'Rotatoria' or 'wheel-animalcules' because of their characteristic anterior 'corona' or 'wheel organ' which imparts an illusion of a pair of. rotating wheels as well as imparts typical 'rotating' locomotion to these organisms. They are also characterized by their jaw-like elements of 'trophi' located in the pharyx; the trophi are modified according to feeding habits of the different species. 'Lorica', yet another salient feature of this group, is formed by thickening of cuticle around the trunk region of their bodies. Depending on the presence or nature of lorica, these organisms are classified as 'loricate', 'semi-loricate', and 'illoricate or bdelloids'

Status Of The Taxon

Global and Indian Status

Rotifera have attracted worldwide attention of naturalists and specialists ever since the invention of the microscope because of their widespread distribution and intricate structure. As a result, these micro-invertebrates have been documented and described from distant parts of the globe and from localities ranging from the Arctic to Antarctic regions as well as transgress\Jlg the continents. Phylum Rotifera includes about 2500 species spread over 200 genera. Of these, 241 species belonging to 21 eurotatorian families and 48 genera were recorded by Sharma and Michael (1980) in 'Synopsis of taxonomic studies on Indian Rotifera' Sudzuki (1989) compiled a list of 575 taxa from the Oriental region which included 250 species from this country. A state of the art report by Shanna (1991), however, incorporated 310 species belonging to 24 families and 60 genera while Shanna (1996) referred to 316 species spread over 24 families and 62 genera. The documented overall biodiversity has not significantly increased since then and 330 species (excluding some doubtful taxa) belonging to 25 families and 63 genera are known to occur presently (Sharma, 1997) in India. The rotifer species known from this country, however, co~prise about 14.8% of the global Rotifera. A conservative estimate (Sharma, 1997) , however, indicates occurrence of over 500 species of Rotifera in this country.

Geographical Distribution In India

About 95% of the rotifer species occur in freshwater which is considered as their original habitat; less than 5% species are reported from continental oceanic environs while they do not occur in open sea. The rotifers colonize littoral, limnetic and benthic regions of inland waters and occur in practically all kinds of ecosystems ranging from small tree-holes or ephemeral pools to large lacustrine and riverine systems as well as prestine subterranean groundwaters. In addition, they are found in manure-pits, psammon, wet bryophytes and lichens as well as in aqualine of the pitcher plants.

Rotifera, as a group, are known for their cosmopolitan distribution yet certain taxa exhibit distinct distributional ranges and, hence, merit significant biogeographical interest. This generalization also holds true for Indian Rotifera which are so far noticed to occur in diverse geographical regions of this country (Shanna, 1996, 1997). At the same time, a number of genera and species are observed to register restricted distribution. This fact is apparently well supported by restricted occurrence of predominantly 'temperate' genera namely Notho1cn, Cephnlodelln and Synchnetn. Various species of the former genus are known to be primarily restricted to the Kashmir Himalayas, the report of N. labis in the river Yamuna near Delhi (Sharma, 1988) is, however, attributed to its drift from higher altitudes. On the contrary, the report of six species of this genus from the river Betwa, Madhya Pradesh (Central India) needs confirmation. The limited information so far avaialable relating to occurrence of species of the other two genera in the Indian waters also reflects their affinity for northern temperate environs. Kellieottia, another distinct temperate element, has interestingly not yet been reported from India. The stated geographical considerations are further augmented by greater species richness of two important 'tropic-centred' genera i.e., Lecane and Brachionlls particularly in its' tropical waters as well as their relative paucity in the rotHer communities from northern latitudes. Besides these salient distributional features, the rotifer fauna of this country exhibits fewer species of 'temperate-centred' brachionid genus Keratella.

Indian Rotifera includes several biogeographically important elements which exhibit both global as well as local or regional distributional interest. Among these, Brachionlls die/lOtomus reduetus, Lecalle batillifer and TestlldinelJa greeni are interesting additions to the fauna of this country; the stated taxa represent Australasian elements which are so documented exclusively from North-Eastern India. In addition, Keratel/a edmolldsolli, Brachiollus dOllneri, Lecalle acanthinllla, L. bifastigata, L. blachei, L. nodosa, L. bulla f ditlbolica, Trichoeerca flagellata and Habrotrocha melicetra are typical Oriental elements. Various Holarctic species reported from India include Eue1llanis alata, Dicranophorus /utkeni, Lecane elongata, L. lauterbomi, L levistyla, L. tryphema, L. galeata, Notommata saccigera, Pleosoma hudsoni, Polyarthra euryptera and P. /ongiremis. Besides, a number of cold-water species particularly belonging to the genus Cepha/odelJa, NotilOlca and Synchaeta are examined from this country.

A number of taxa of local or regional distributional importance are noticed in the rotHer fauna of India and these include BrachiollllS dimidiatus, B leydigi, B. mirabilis, B. pterodinoides, Keratella edmondsoni, K. lenzi, K. javalla, K. ticinensis, Platyias leloupi, Crytonia tuba, Euch/anis brahmae, E. alata, E. deflexa, Pseudoeuc1llanis longipedis, Tripleuchlanis plicata, Mytililla acanthopllOra, M. bisulcata, Wolga spinifera, Colurella adriatica, C. sulcata, Lepadella aspida, L. costatoides, L. dactyliseta, L. Irostei, L. longiseta, L. minuta, L. triba, Leca,te acronycha, L. bifastigata, L braumi, L. althausi, L haliclysta, L. ligona, L. nodosa, L. rutterni, L. simonmeac, L. sola, L. blachei, L. syngenus, L. acanthinula, I. bifurca, L. furcata, Cephalodella giganthea, C. intuta, C. hiulca, Eosphora anthadis, Taphrocampa selemura, Trichocerca brazieliensis, T. chattoni, T. jenningsi, T. kostri, T. tropis, Dicranophorus dolerus, D. lutkeni, D. tegillus, Sinantherina spinosa, S. semibullata, Hexarthra bulgarica, Filinia camascela, F. cornuta, F. saltator, F. pejleri, Testudinella brevicaudata, T. tridentata, Pompholyx complanta, Cupe/opagis vorax, Adineta valga, Habrotroc1ra angusticolis, H. aspersa, H. constricta, H. lata, H. Ieitgebii, H. perforata, Philodina indica, Embata Iaticeps, Macrotrachela bullata, M. formosa, M. habita, M. musculosa, M. papillosa, Rotaria mento and R. sordida.

Interestirtgly, a number of species described earlier from India now exhibit extended distributional ranges. Dhanapathi (1974) described an interesting brachionid rotifer i.e., Braehionus durgae from Andhra Pradesh; this species is presently reported to depict Cosmo (sub) tropical distribution (Segers et al., 1994). In addition, B. donneri and Keratella edmondsoni were described by Brehm (1951) and Ahistrom (1943) respectively from Tamil Nadu in Southern India. These two species are considered (Sanoamuang et aI., 1995) to be Oriental elements. Leenne lateralis is yet another example of distributional interest; this lecanid was described from West Bengal (Sharma, 1978), later on reported from Orissa, was believed to be an Indian endemic. It, however, is now known to be a palaeotropical element (Segers, 1996). On the other hand, the rare L sola, described from Tamil Nadu (Hauer, 1936) exhibits pantropical distribution (Segers lac., cit.); besides type locality' in South India, it is recently reported from Tripura State, in North-Eastern region (Sharma and Sharma, 1997) and, hence, its distributional range is considerably extended in this country. Further, Triehoeerea tropis, described from Tamil Nadu (Hauer, 1937a), is a cosmotropical species (Segers et al. , 1993). Horaella brehmi, an interesting illoricate rotifer described from Bihar (Donner, 1949), exhibits pantropical distribution (Sharma, 1991). Moreover, Segers et al. (1993) examined certain neotropical specimens identical with Lepadella bieornis which was, in tum described earlier by Vasisht and Battish (1971) from North India.

Qualitative diversity of Rotifera in different States of India (Fig. 1) reflects a distinct uneven picture of their species richness. Apparently, the rotHer fauna of West Bengal (148 species) is fairly well documented and is followed by the report of 110 species from Meghataya (Sharma and Sharma, 1997) as well as an equal number of species from the State of Tripura (Sharma, unpublished). Ironically, information about distribution of the rotifers in mentioned States is also yet far from complete because of inadequate analysis of taxa particularly of the littoral, benthic and bdelloid communities.

The number of species known from different States, in fact, provides a misleading information about their overall rotHer diversity, the reality, however, is otherwise as the presently available information is based on contestedly insufficient collections and do not include representatives of various communities. On the contrary, the reports of 90 and 82 species by Edmondson and Hutchinson (1934) and WuUert (1996) respectively and based on analysis of limited but heterogeneous samples obtained from diverse aquatic biotopes also supports the stated remarks. The above generalizations focus emphasis on exsitensive state-wise/regional faunistic surveys involving collections from various habitats/ecosystems and following suitable sampling techniques. Due attention is also required on the examination of more material from already studied regions to provide an exhaustive information on the distribution of Rotifera and to explain latitudinal and longitudinal distribution patterns of various taxa (if any).

Biological Diversity And Its Special Features

The members of sub-class Monogononta (300 species) comprise the significant fraction (90.9%) of the Indian Rotifera and are spread over 56 genera. On the other hand, only 30 species of the digononts, belonging to seven genera, are represented in this country. The former are dominated by the Ploimida (255 species, 77.3%) while order Gnesiotrocha constitutes a relatively smaller fraction (45 species, 13.6%) of the documented species. The observed pattern of species richness of the stated two orders is in conformity with general compOSition of the Oriental fauna (vide Sudzuki, 1989) and indicates paucity of information relating to the bdelloids in particular. Family¬wise break up of the rotifer fauna of India (Table -1) depicts qualitative importance, in the stated sequence, of Lecanidae > Brachionidae > Colurellidae>Notommatidae>Trichocercidae; these families comprise a notable fraction of overall species richness (193 species, 58.5%). In addition, three other monogonont families namely Euchlanidae, Floscularidae and Testudinellidae form a valuable component (37 species, 11.2%).

The rotifer taxocoenosis of India depicts broadly a tropical character as characterized by abundance of 'tropic-centred' genera namely Lecane and Brachionus speices. Such a generalization is applicable to the rotHer communities from different parts of this country in general except those from its northern latitudes. The indicated nature is also supported by fewer species (10 species) of 'temperate-centred' brachionid genus Keratella and restricted occurrence of other 'cold-water' genera namely Cephalodella, Nathalca and SyncllQeta. As mentioned earlier, various Notho/ca spp.reported so far from India are primarily restricted to the Kashmir Himalayas.

Cosmopolitan elements comprise a significant component (about 52%) of the Indian Rotifera. In addition, tropical and pantropical species are well represented (about 20%) in the rotiter communities examined from this country. The documented taxocoenosis includes three Australasian elements and several Oriental, Holarctic and Palaeotropical species while a number of species described from India are now reported from elsewhere and, hence, assume global distributional importance. Such examples have been discussed separately in this account under the section of 'geographical distribution'

The rotifer biodiversity registers interesting variations in hard-alkaline waters in different parts of tropical India as well as in soft and acidic to slightly alkaline aquatic biotopes particularly in its North-Eastern region. Planktonic Rotifera from the former are characterized by abundance of alkalophilic Brachionus species and Keratella tropica. On the contrary, the latter are marked by common occurrence of Keratella eoehiearis and certain eurytopic brachionids such as Brac1zionus angularis and B. calyciflorzts while Keratella lellzi, B. forficlIla, B. falcatus and B. dOlllzeri are frequently noticed in limnetic communities. The relative paucity of BrachionllS spp. in the second category of waters is attributed their acidic nature; this important feature is in conformity with the observations by Fernando and Zankai (1981), Sanoamuang et al. (1995) and Segers (1996). Further, a number of typical acidophilic elements so far reported from India are reptesented by Brac1zionus mirabilis, Plationlls patulus macracalltlzus, Euchiallis triquetra, Mytilina bisulcata, Colurella sulcata, Lepadella cristata, L. nartiallgellsis, L. dactyliseta, Lecane doryssa, L. jaintiaensis, L haliclysta, L. pertica, L. illermis and L. seutata.

The limited nature of investigations from India does not provide adequate information about the biological diversity of Rotifera in different ecosystems. Referring to the lentic biotopes with aquatic macrophytes, fairly extensive observations by the author from West Bengal indicaed total 72 species and those from Meghalaya reflected overall qualitative diversity ranging between 58-64 species while Sharma and Dudani (1992) documented 53 species from five such ponds from Bihar Further, Sharma and Sharma (1997) indicated upto 50-55 species from ephemeral paddy-field ecosystems of Meghalaya with maximum of 28-33 species/sample in contrast to upto 18-22 species/ sample recorded earlier from the state of West Bengal. Planktonic rotifer communities, however, depicted maximum 18-22 species/ ecosystem in Meghalaya and 28-33 species/ecosystem in West Bengal while Michael (1968) reported a total of 30 rotifer species from a fishpond in the latter state. The flood-plain lakes, interesting ecotones with considerable variations in micro-ecological conditions, serve as unique habitats for colonization of diversified aquatic communities in general and the rotifers in particular.

However, species richness of this phylum in the stated biotopes is yet very poorly documented in India and the published literature reflects very poor diversity i.e., maximum upto 40 species because of the study of inadequate collections. The samples examined by this author (Sharma, unpublished) from certain flood-plains of the Upper Assam region of the Brahmaputra basin have revealed about 90 species as well as occurrence of upto 54 species/ samples outlined the significance of the hypothesis proposed by Segers et al. (1993b) for (sub) tropical flood-plains and an urgent more data on their rotUer diversity in India.

Among other lentic habitats, the limited studies undertaken in prestine waters of the domestic wells has so far revealed only 16 species of monogonont rotHers. in addition, preliminary observations in insular freshwater from the greater Andamans (Sharma, unpublished) indicated only 45 species. More collections from the stated biotopes need to be examined to assess qualitative diversity of Rotifera.

The rotUer communities of the riverine ecosystems of India appear to be less diverse since a majority of workers reported upto 20 species while Adholia (1979) examined 33 species from the river Betwa (Madhya Pradesh) and Sampath et al. (1979) observed 35 species in the river Kaveri. On the other. hand, the recent study by Sharma and Naik (1996) dealt with distinciy higher .species richness (72 species) from the river Narmada in Central India, thereby, indicating the importance of proper sampling from lotic waters. Referring to two 'global hot-spots' of biodiversity significance, the studies initiated by this author from certain states of North-Eastern India provide useful information while the rotHer communities from Western ghats are still poorly documented. In all 132 species belonging to 32 genera and 19 families are so far reported from the former region. These, in tum represent 40.6% and 50.8% of total species and genera known from this country respectively. Needles to mention, the rotifer taxocoenosis of N. E. India requires further updating and as per a conservative estimate over 250 species are expected to be recorded from this region. Further, the rotifer richness examined from this region is broadly comparable with other S. E. Asian countries.

The rotHer fauna of North-Eastern India is characterized by more qualitative diversity of Lecane and relative paucity of Brachionus spp.-a feature well in conformity acidic nature waters and fewer permanent lentic biotopes as also suggested earlier by Fernando and Zankai (1981), Sanoamuang et al. (1995) and Segers (1996). The former aspect is supported by occurrence of various acidophilic elements namely Brachionus mirabilis, Plationlls patulus macracantltus, ElIcltlanis triquetra, Mytilina bisllicata, Colurella sulcata, Lepadella cristata, L. nartiangensis, L dactyliseta, Lecane doryssa, L. jaintiaensis, L. haliclysta, L. patica, L. internlis, L. sClIatata and Testudinella emarginllia. Interestingly, three Australasian elements i.e., Brachionus dichotomlls redllctlls, Lecane batillifer and Testlldinella greeni ascertain a close relation of the rotifer fauna of N. E. India with southeast Asia and Australia. Besides, the holarctic Lecame levistyla, reported recently (Sharma and Sharma, 1997) from Tripura State of this region comprises the first record of this rare lecanid outside the northern Hemisphere.

Endemicity

The rotifer fauna of India includes only 23 endemic species which, in tum, represent nearly 7.0% of the documented species; these mainly belong to Lecane (9 spp.) and Lepadella (4 spp.) and therefore, support the remarks of Dumont (1983) on the presence of unusual endemics of the stated genera in southeast Asian faunas. On the other hand, the absence of Indian endemic species in the family the Brachionidae is believed to be secondary (Dumont, loc. cit.) and this aspect is attributed to the loss of characteristic taxa after the Indian plate hit Asia and invasion of the Oriental faunal elements to the near East especially during the Pleistocene. In addition, the Indian Rotifera includes two monotypic endemic genera namely Pselldoellchlanis and Pselldoembata; of these, the taxonomic status of the former warrants confirmation (refer : Segers, 1996). These general remarks are not an index of paucity of the endemics in this country. However, the fact is that future investigations on the littoral rotifers are expected to consolidate the list of endemic species since these communities, in particular, are known to include interesting endemic elements (Segers, loc. cit.).

Introduced And Threatened Species

The classical instances of individual introduced species refer to extension of distributional ranges of Kellicottia bostomiensis in Scandinavia, Keratella tropica in Holland, Belgium, France and Spain, Brachionlls variabilis in Belgium and B. falcatlls in South-western France. However, in all cases human participation in introducing resting eggs along with import of fish, water plants, etc. is anticipated. No attempt has so far been made to evaluate the rotifer species of this category in the faunas of the Oriental region as well in Indian Rotifera. Apparently, occurrence of several Arctic-temperate, Neotropical, Australasian and Holarctic elements in this country presents ample proof of introduced elements. Hence, it will be worthwhile to focuss special attention on this aspect in future investigations. However, no information is yet available relating to 'threatened species' of Rotifera in India or elsewhere in the world. SHARMA: Rotifera

Value

Rotifera invariably comprise an important qualitative and quantitative component ?f freshwater microinvertebrate biocoenosis in general and limnetic as well as littoral zooplankton communities in particular. Various taxa of this phylum exhibit interesting latitudinal distributional patterns and, hence, serve as valuable material for biographical considerations. They represent an integral link in aquatic food-chain and also themselves comprise an important component of food-spectrum of fry, fingerlings and even adults of various commercially cultivable freshwater fish species. In addition, their importance as suplementary food in various aquaculture practices is undisputed. The rotifers contribute significantly to overall biological productivity in freshwaters because of their rapid tum-over rates and metabolism and also due to the fact that many species of this group feed on detritus and bacteria and are, therefore, consequently to a great extent independent of autotrophic production.

Various rotifer taxa serve as useful bioindicators of water quality of their environments within the limits of limnosaprobity, this fact has been ascertained by the reports from different parts of the world. Even the raHo between Bracllionus : Tricllocerca species (Sladecek, 1983) is regarded as an important index to depict trophic status of different ecosystems or of individual plankton collections. Their ability to colonize diversified aqautic and semi-aquatic biotopes and an inherent quality to build up substantial densities within short time-intervals makes them ideal objects for ecological considerations as well as valuable tools for population dynamics studies. Further, the soil-rotifers play an active role in promoting the soil fertility. The members of this phylum are being increasingly used in ecotoxicological studies and environmental bioassay experiments. The latest biotechnological advances dealing with mass rearing of fast-growing strains of selected species of these organisms merit special interest. Above all, there is yet no evidence that the 'Rotifera are injurious to any animal or plant that is of iinportance to human beings.

Threats

The species composition and abundance of the rotifers is intricately influenced by ecological changes/perturbations in their environments. The phenomena of cultural eutrophication, acidification, siltation, vertebrate (fish) predation, habitat destruction due to removal of aquatic macrophytes for fisheries development and influx of the different pollutants exercise drastic impact on their community structure and may threaten the survival of Rotifera. In addition, ecological changes associated with ontogeny of aquatic environs influence and change the structure and production of the rotifera communities.

Future Studies

Systematic studies on the rotifer taxocoenosis of Asia in general and the Indian subcontinent in particular are still in initial stage. Hence, updating of the rotifer fauna of this country as well as providing detailed species inventories from different regions/States of India holds the main scope for future studies. All such endeavours, however, must be supported with SEM observations on various morphological attributes as well as detailed structure of trophi of various taxa which undoubtedly serve as important diagnostic features. Illustrated taxonomic keys to the regional rotifer faunas or to the fauna of India are highly desired to resolve the existing nomenclatural discrepancies and to ensure correct identification of taxa in limnological investigations. Detailed statistical analysis of morphometric variations of different population of various species shall go a long way to explain questions related to morphospecies and to resolve aspects of vicariance. Further, more observations on ecotypic and cyclomorphic variations are required in the Indian taxa.

Ironically, a number of rotifer workers in this country have invariably resorted to descriptions of new species without allocation of type-specimens or even without making any reference to such material in their original publications. Hence, proper alloction of type-specimens must be ensured. A national depository of rotifer collections from different parts of India is desired to serve as ready reference for future workers.

Besides general taxonomic considerations, it is necessary to analyze and copare qualitative diversity of rotifers in the varied aquatic biotopes in general and to provide comprehensive information on littoral, benthic, sessile, semi¬sessile, colonial and bdelloids in particular. It will be interesting to examine the rotiter species associations in different habitats with reference to the basic parameters of water quality as well as those with different kinds of aquatic macrophytes. Adequate attention is to be focussed on the composition and biological diversity of Rotifera in different lentic and lotic ecosystems with special reference to their community structure in unconventional biotopes such as the flood-plain lakes or beels, wetlands, rice-fields, ephemeral water bodies, riverine systems and prestine groundwaters.The rotifer taxocoensis of insular freshwaters of the Andaman and Nicobar Islands and the Lakshadweep archipelago holds interest for future workers. All the above stated aspects will certainly remain meaningless without analysis of latitudinal and longitudinal distributional patterns. In addition, it is necessary to undertake faunistic surveys in estuarine ecosystems of this country.

The future in-depth synecological studies based particularly on short sampling intervals and detailed analysis of the rotifer communities are desired from tropical, sub-tropical, and temperate freshwater environs of India to acquire meaningful data. Theimpact of abiotic and biotic parameters on abundance and ecology of this group should be analyzed with support of appropriate statistical tools. Attention is also to be focussed on long-term temporal changes in the rotifers and on horizontal and vertical distributional patterns of various taxa. Influence of invertebrate and vertebrate (fish) predation on the community structure and production of organisms needs to be assessed.

The laboratory and field observations on embryonic durations, tum-over rates, cohort production, instantaneous birth, death and growth rates as well as on other population parameters at least of selected dominant species are much desired to examine their role in zooplankton dynamics and biological productivity in freshwaters. Estimation of biomass of the rotifer communities in the different ecosystems is yet another important aspect which merits attention in the future investigations. Besides, detailed autecological studies on the selected species are desired to supplement initial observations undertaken so far in India. Evaluation of regional target species of the Rotifera as well as attempts at the mass rearing are to be taken up to supply much needed supplementary food for inland pisciculture practices.

Evaluation of regional bioindicator rotifer species deserve attention of the Indian workers. Application of Sladecek's quotient based on Bracllionus.: Tricllocerca species ratios should be extended the rotifer communities of different water bodies to assess and compare their trophic status. The limited earlier observations from India have indicated special features of the rotifer species in typical alkaline as well as acidic waters. Further observations are desired to affirm acidophilic and alkalophilic affinity of various species or to supplement related data. Certain Indian taxa namely Bracllionus dimidiatlls, B. dicllotomlls redllctus, B. donneri, B. durgae, Keratella javana, K. lenzi, Pseudoeucltlanis longipedis Asplanclmopus bimaberaensis and Horaella brellmi have been included earlier under category of those preferring special waters (status yet not determined). Hence, special attention need to be focussed on the stated rotifers to examine their specific ecological requirements. Faunal Diversity in India

Selected References

Bartos, E. 1959. Virnici-Rotatoria Fauna CSR, Praha, 15: 1-969. De Ridder, M. and Segers, H., 1997. Rotifera Monogononta in six zoogeographical regions after publications between 1960-62. 5tudiedocllmenten van het Koninklijk Belgisch Instiut voor Natuurwetenschappen (J. Van Goethem Ed.), 87 : 1-481. De smet, W. H., 1995. Rotifera 3. The Notommatidae and 5caridiidae. Guides to the identification of Microinvertebrates of the Continental water of the World. Vol. 8 (H. J. Dumont and T. Nogrady Eds.) SPB Academic Publishing by. Amsterdam, The Netherlands. De Smet, W.H., 1996. Rotifera 4. Tire proalidae (Monogononta). Guides to the identifications of Microinvertebrates of the Continental waters of tile world. Vol. 9 (H. J. Dumont and T. Nogrady Eds.). SPB Academic publishing bv. Amsterdam, The Netherlands. De Smet, W.H. and Purriot, R, 1996. Rotifera 5. The Dicranoplwridae (Monogononta) and the. Ituridae. Guides to the identification of Microinvertebrates of the Continental woters of the world. Vol. 12 : 1-350 (H. J. Dumont and T. Nogrady Eds.). SPB Academic publishing by. Amsterdam, The Netherlands.

Donner, J. 1965. Ordnung Bdelloidea (Rotatoria, Riidertiere). Best. Bucher z. Bodenfauna Europas, 6 : 1-297, Berlin.

Dumont, H. J., 1983. Biogeography of rotifers. Hydrobiologia, 104 : 19-30. Koste, W., 1978. ROTATORIA. Die Riidertiere Mittleuropas, begriindet von Max VOigt. Uberordnung Monogononta. Gebriider Borntraeger, Berlin, Stuttgart. I. Test. (1-673) u II. Tafelbd. (T. 1-234).

Nogrady, T., Wallace, R. L. and Snell, T. W., 1993. Rotifera I. Biology, Ecology and Systematics. Guides to the Identification of the Microinvertebrates of the Continental waters of the World ( H. J. Dumont and T. Nogrady Eds.) 4 : 1-142. SPB Academic Publishing by. Amsterdam, The Netherlands.

Rudescu, L., 1960 Rotatoria. Fauna R.P. Rominae, 2 (2) : 1-1192. Segers, H., 1995a. Rotifera 2. Tire Laecanidae (Monogononta). Guides to the identification of the Microinvertebrates of the Continental water of the World. Vol. 2 : 1-226 (H. J. Dumont and T. Nogrady Eds.), SPB Academic Publishing by Amsterdam, The Netherlands. Sharma, B. K. 1991. Rotifera. In : Animal Resources of India: Protozoa to Mammalia. State of the Art, Zoological Survey of India, Calcutta: 69-88.

Sharma, B. K. 1996. Biodiversity of Freshwater Rotifera in India-a status report. Proc. zool. Soc., Calcutta, 49 : 73-85.

Rotifera

This is an extract from ANIMAL RESOURCES OF INDIA: Protozoa to Mammalia State of the Art. Zoological Survey of India, 1991. By Professor Mohammad Shamim Jairajpuri Director, Zoological Survey of India and his team of devoted scientists. The said book was an enlarged, updated version of The State of Art Report: Zoology Edited by Dr. T. N. Ananthakrishnan, Director, Zoological Survey of India in 1980.

Note: This article is likely to have several spelling mistakes that occurred during scanning. If these errors are reported as messages to the Facebook page, Indpaedia.com your help will be gratefully acknowledged.

Introduction

The rotifers comprise a group of pseudocoelomate microscopic organisms usually ranging in size between 40 Jlm -250 Jlm while some large species (rarely extending upto 2.5 mm) can be percicved by the unaided eye as minute dots, sacs or rods. They have been invariably treated as a class of the Phylum Aschelminthes or even as a distinct phylum by some authors and they exhibit many structural features in common with Gastrolricha and Nematoda. Clemente (1980) atlributed their affinity to Platyhelminthes and postulated that these two groups probably had a common ancestor. According to Sladecck (1983), the rotifers represent a very old group of invertebrates and are presumed to be a product of the aerobic phase in the development of our planet though there is yet no palaentological evidence to support this view.

These fascinating creatures have long been called Rotifera or 'Rotatoria' or 'Wheel-animalcules' as their disc-like anterior end (corona) bears resemblance to a pair of revolving wheels owing to the synchronized beating of their coronal cilia. These are also characterised by a specialized pharynx called the mastax, with its cuticular lining differentiated into trophi which act as jaws. These micro-organisms shows remarkably intricate structure and exhibit endless profusion in their body fonns which are morphologically well adapted to their living habits and closely related to their habitats. The vast majority of rotifer encountered under natural conditions are females, males, however, are known relatively for a few species, they are diminutive, degenerate and seldom survive for more than a couple of days. The rotirers show world-wide distribution, possess striking 'ability to colonise diversified biotopes and indicate rapid tum-over rates. They reflect interesting strategies for reproduction, population dynamics, spatial and vertical distribution and survival while some of them are notable for the ecotypic and cyclomorphic v~tions and prey-avoidance mechanisms. .

Rotifers are mainly found in freshwater which is considered their original habitat. However, during the course of their evolution to the present multiplicity, they have invaded and become adapted to various other habitats. As a result, they are now encountered in a wide range of aquatic and semi-aquatic environs. They are more important in freshwater ecosystems because of their occurrence in practically all biotopes varying from a trickle on the rocks and small tree-holes to large rivers, from bogs to inland salt water lakes and from ephemeral polls to the limnetic, littoral or deepest regions of the largest lakes.

This view is supported by the fact.that about 95% of the mtifers are known from freshwater habitats while less than 5% of them are known to restrict in marine or brackish waters. Amongst the groups of the animal kingdom which established in freshwaters, only few succeeded in leaving the bottom to inhabit the pelagial region. Rotifers are prominent than almost any other such group to adapt to the open water as about 30% of the,rotifer genera live constantly or occasionally in the plankton. Besides aquatic ecosystems, the rotifers occur in decomposing vegetable debris (e.g. manure pits),. in mosses dampened onJy occasionally and in the interstices between the sand grains of lake and river beaches from the Arctic and Antarctic to the Tropics. The rotifers comprise an important component of soil micro-invertebrate communities (the Edaphon). Freshwater environments are predominated by the monogononts while only 20-30% of bdelloids inhabit the shores of these ecosystems. On the other hand, about 95% of the rotifers found in mosses and soil are bdelloids.

A majority of these organisms are free-living and solitary, sessile or colonial taxa belong only to a few families. A few species of rotifers are known to take to commensal or synoecious associations with freshwater cladocerans, snails, insect larvae, prawns and other lower crustaceans. Only few species are reported to be parasitic on some coloniaJ or filamentous algae (e.g. Volvox, Vaucheria) and aquatic worms (May, 1989).

Importance: There is yet no evidence that rotifer~ are injurious to any animal or plant that is of importance to human beings. They, however, comprise an integral link in the aquatic food-chain; the part played by them in the biological productivity is of considerable significance partly because of their rapid turn-over rates and metabolism and partly. because many species largely feed on detritus and bacteria and are consequently to a great extent independent of autotrophic production,. The rotifer invariably constitute a dominant component of freshwater Zooplankton and , hence, contribute significantly to their dynamics and production. They often serve as food for fry, fingerlings and adults of various commercially important and culturable species of fishes. It is in this context that during the last couple of decades considerable attention has been focussed on intensive culture of various species of freshwater and brackish water rotifers as supplementary food for aquaculture practices. These organisms are regarded as valuable bio-indicators to depict the trophic status of water quality of their environments within limnosaprobity (Sladecek, 1983; Berzins and Pejler, 1989) and, therefore, these organisms are being increasingly used in environmental toxicological studies and bioessay experiments. The soil rotifer~ play an important part in the food balance of these biotopes owing to their abundance and wide range of feeding habits. They aid countless other micro-organisms in promoting the proliferous structure of the soil by constructing their nests between gains, depositing their wastes ans fmally adding their own dead bodies. .

Nomenclature: Leeuwenhoek (1703) was the first to provide figures and descriptions of rotifers (particularly bdelloids) but considered them as protozoans. Linnaeus (1758) listed three species of these organisms under Zoophyta. Baker (1764) mentioned them as Wheel-Animals but did not auempt any classification. Muller (1773, 1786) and Pallas (1776) described many species but considered them Infusoria. euvier (1798) placed them in Kingdom Zoophytes, Class Infusories.

The term Rotifera, however, was first applied by Du Trochel (1812) who also regarded them as a biological unit set apart from Protozoa. Lamarck (1816) considered them as section of the order Polypes Cilies among 'animaux apatiques' corresponding to Zoophyta of Cuvier. Ehrenberg (1832) treated them as a class of Infusoria and proposed the term Rotatoria. Ehrenberg (1839) classified Rotifera among the worms. Metschnikoff (1864) established the distinction between them and Gastrotricha.

Hastschek (1878) recognised the trochophore larvae and Rotifers as having the same grade of structurc. Zelinka (1889) included both Rotifera and Gastrouicha under Aschelminthes. Remane (1929-33) believed them to be the larvae of unknown worms that remained in their larval stage. Various other considcrations on this group are detailed in the works of Edmondson (1959), KuLikova (1970) and Koste (1978).

Till recently, the terms ROLifera and Rotatoria have been frequently used for this group. Ricci (1983) questioned the nomenclatural validity of the use of these tcnns and after critically reviewing the literature recommended that the term 'Rotifera' by Cuvier (1798) should be regarded as the correct name while 'Rotatoria' by Ehrenberg (1832) was proposed as a synonym of the former.

Classification: As mentioned earlier, Rotifera are more commonly included as a Class of the Phylum AschelminLhes while Edmondson (1959) also considered them as a separate Phylum. Various earlier auempLS at classification of this group presented a number of anomalies. The first standard classification was proposed by Harring (1913) but the detailed classification of Remane (1929-33) laid the foundation for the systematic work of Voigt (1957) but .some changes were subsequently incorporated by Edmondson (1959), Sudzuki (1956), Dc Beauchamp (1965), Kutikova (1970) and Kostc (1978). Other diagnostic works were by Rodescu 1 (1960), Dommer (1965) and Ruuner-Kolisko (1974).

The general system of classification followed in this account is after Koste (1978) and for specific work on bdclloids the publication by Donner (1965) is taken into consideration. The division of class into subclasses and order derives from the slIucture of the female genitalia while families and lower subdivisions are differentiatoo on the structure of corona and the types of trophi.

Freshwater rotiCers belong to various families of Sub-class: Eurotatoria and marine fonns are represented by only one genus (Seison) of sub-class Seisona (Family Seisonidae). Bdelloids (Super-order Digonota) comprise an important component of moss-dwelling and soil rotiCers.

Historical Resume

The rotifers were first studied and described by Lecwenhoek (1703) following the invention of microscope. Since then, these interesting organisms have drawn world-wide attention of amateur naturalists as well as professional hydrobiologists because of their intricate structure, profusion of body forms, wider di~tribution and easy availability. However, studies on this group from India date back to later part of the 19th century. Various investigations related to taxonomy, zoogeography and ecology of rotifers from this country are detailed below under three periodic levels:¬

i) Pre-1900

This period incorporates the sole contribution of Anderson (1889) who initiated faunistic studies• on freshwater rotifers from India. His collections from various aquatic ecosystems in and around Calcutta (West Bengal) dealt with 47 species, including the descriptions of 10 species and two uncertain species.

ii) 1901-1947

The studies during this period commenced with a list of 32 species of rotiCers from the slopes of the Sikkim Himalayas, between altitudes of 610m -2440m (Murray, 1906). This list included 8 species each of the genera JJabrotrocha and Macrotrachela, 7 species of Philodina, 3 species of Rotaria and one species each of the genus Adineta, Proales, Squatinella, Colurella, Lecane• and Brachionus. The predominance of bdelloids in Murray's material was due to the fact that these collections were made from mosses. After a time-lag of nearly three decades, Edmondson and Hutchinson (1934) examined samples obtained by Yale North India Expedition from 52 localities in the Punjab and Northwest Frontier Province (all parts now in Pakistan), 15 localities in the Kashmir basin (altitude between 1585m -2620m)', 24 localities in the then Indian Tibet and. the extreme western part of the Tibet Propcr (altitude between 3200m -5334m) and 9 localities from the Nilgiri Hills in Southern India (altitude between 2133m -2316m). These authors enumerated 99 species (excluding a few doubtful forms) from the mentioned samples that were taken mostly from alkaline waters at moderate or low temperatures.

This paper included taxonomic and Zoogeographical notes, morphological variations in Cephalodella catellina, Filinia longisela. Keratella valga and K. quadrata and comments on the rotatorian fauna of high altitudes. Edmonson and Hutchinson also gave a list of 37 valid spccies amongst those documented earlier by Anderson (1889).

Dr. R. B. S. Sewell, Late Director, Zoological Survey of India initiated work on rotifers in this institute. Sewell (1934) in his comprehensive study of the fauna of Salt Lake, Calcutta referred to five species from brackishwaters i.e., Brachionus pala (= B. calyci[lorus), B. bakeri (= B. quadridentatus), B. rubens, B. urceolaris and Asplancha brightwelli and two varieties of B. bakeri. Of these, A. brighlwelli was also reported to be common in freshwaters in and around Calcutta. Subsequently, Sewell (1935) gave a classical account of fauna of the tank in the Indian Museum compound and its seasonal changes based on the collections made during 1929-31. This paper dealt with 11 specics of rotifers and their seasonal occurrence.

Karlsruhe worked on collections sent by Prof. (Dr.) Chappius, from some lakes in the then Madras Presidency and published three papers. First one dealt with the description of Lecane sola from Almati lake and Monostyla conspic14a M. bulla, f. diabolica n. f. from Sholavarum lake. In addition, two new species of Trichocerca from Almati lake were documented in second one (1937) and third one (1937) dealt with a new variety and new form of Brachionus angularis from

Sholavarum and Almati lake. Ahlstrom's (1940) paper on the rotatorian genera Brachionus and Platyias referred to the material examined by Hauer (1937). Further, Ahlstrom (1943) in his revision of the genus Keratella dealt with a new variety of Keratella quadrata from Ootacamund lake, MadrasLittle was known about the ecology of rotifers till the end of this period. Edmondson and Hutchinson (1934) referred to pH and water temperat~e while Sewell (1934) dealt with the salinity of the examined samples. Sewell (1935) made an attempt to explain seasonal chang~s of the fauna in relation to certain ecological parameters observed earlier by Pruthi (1933). This information was supplemented by Ganapati (1943) in his comparative swdy of plankton abundance in a garden pond at Madras.

Various earlier works till 1947, even though fewer in number, made significant contributions to systematics and distribution of rotifers in India, gave information about fauna of Salt Lake and initiated ecological studies on this group.

iii) 1948-1990

The period between 1948-1960 included a few taxonomic publications based on the collections by Dr. V. Brehm, Limnologial Institute, Lunz am See, Austria and those examined by J. Donner (an Austrian monk). Donner (1949) described Horaella brehmi"nov. gen. et. nov. sp. from a tank in Banikpore, Bihar (collection v. Brehm, dated 13.9.1902) and listed another five species of rotifers, three species of cladoceran and two sp~ies of copepods from this sample. Further, Donner (1953) referred to Brehm's material from a filtration bed in Madras while describing Trichocerca (Diurella) ruttneri from Java and Sumatra, India and Neusiedlersee (Austria). Brehm (1950) in his article on the freshwater of India (part II) dealt with three species of rotifers, including Keratella cochlearis from Palta water works in West Bengal. Subsequently, Brehm (1951) described Br.achinus donner; an interesting brachionid, fr,om Almati reservoir, Madras~

During 1951-60, contributions to rotifers ecology comprised parts of few studies on plankton ecology. Ganapati and Chacko (1951) studied plankton production and limnology of four fish ponds at the Chetpat fish farm, Madras while Chacko and Krishnamurty (1954) dealt with plankton on three freshwater ponds in Madras city. Dutta el al., (1954) made observations on seasonal and periodic fluctuation in the plankton of Hooghly Estuary ~tween a stretch of 68 miles from Palta to Diamond Harbour. Roy (1955) analysed plankton ecology of Hooghly river at Palta. Alikunhi et al., (1955) examined quantitative variations of rotifers in a few nursery ponds at Cuttack (Orissa), though annual population was not attempted. The studies of Das and Srivastava (1955, 1956, 1956b) dealt with quantitative fluctuations of plankton and their ecology in a fi~h-pond and some tanks at Lucknow(Uttar Pradesh).

From 1961 onwards, there was considerable proliferation of researches related to systematics and ecology of these organisms from scattered localities and involving participation of workers from various institutions and universities. Different developments are treated separately in three following decades in view of accwnulation of vast and diversified literature. The decade between 1961-1970 included taxonomic studies from Tamil Nadu. Pash (1961) reported six species of lecanids. from freshwater tanks and Coovum river in Madras. Hutchinson (1964) resurrected Filinia pejleri based on the figure given earlier by Edmondson and Hutchinson (1934) from Ootacamund lake (Madras).

In addition, Michael (1966) described a colonial rotiCer, Conochilus madurai from Madurai while Wycliffe and Michael (1968) dealt with Pseudombale acutipoda an epizoic bdelloid from gill¬chambers of Caridina sp. From the state of Maharashtra in western India, Arora (1962, 1963, 1963, 1965, 1966, 1966, 1966) presented a faunistic account of rotiCers from polluted and clean water bodies in Nagpur city, gave ecological notes for different studied taxa and made observations on cyclomorphosis in Brachionus calyciflorus, Keratella tropica and Platyias patwus. Dvorakova (1963) examined rotifers from the Yamuna river, and described a new species of the genus Lecane.

Nayar (1964, 1965) studied morphometric variations and cyclomorphosis in Brachionus calyciflorus from Rajasthan and documented (Nayar, 1868) 36 species (including on new species) of rotifers from this state. Nayar (1965b) gave taxonomic notes on Indian species of genus Keratella. Further, Nayar and Nair (1969) reported 15 taxa of southlbrachionid rotifers from Kerala in India. Wulfert (1966) examined collections, from Ajwa river and Nimeta Water works, Baroda sent to him by Drs. Ganapati and Jayangounder and dealt with 81 species (including 9 new taxa and one new combination).

George (1966) made observations on cyclomorphosis in Keratella tropica from Roshnara tank, Delhi. Naidu (1967) initiated systematic investigations from Andhra Pradesh and dealt with 12 species from temporary rainwater puddles at Vijayawada and two old wells at Cuddapah and Chittoor. Subsequent studies of Vasisht and Gupta (1961) and Vasisht and Battish (1969, 1970) contributed 26 species from Chandigarh (Union territory) in North India Vasisht and Dawaf (1968) gave f1l'8t description of male of Cupelopagis vorax from• this city while an elaborate account of anatomy and histology of Lacinulariaflosculosa was presented by Vasisht and Dawar (1970)

Ecological studies indicated co~siderable impetus during 1961-1910. Arora (1961) made observations on responses of rotifers to variations in some ecological factors (temperature, pH and dissolved oxygen). Arora (1961, 1966) made fust attempt to designate trophic indicators amongst rotifers based on his observations in different water bodies in Nagpur city. George (1961) examined abundance of rotifers in five fish tanks at Delhi and later (George, 1966) gave a detailed account of comparative plankton ecology in these ecosystems. Moitra and Bhowmik (1968) studied seasonal cycles of rotifers in a freshwater fish pond at Kalyani (West Bengal). In addition, observations on the rotifer populations of two ponds at Pilani, Rajasthan were made by Nayar (1970).

Some more investig~tions on rotifers as part of general plankton studies were from ~ataka (Gounder and Patil, 1961), West Bengal (Shetty et al., 1966; Moitra and Bhattacharya, 1966; Michael, 1968, 1969), Uttar Pradesh (Dcvassy; 1965; Roy el at., 1966; Pahwa and Mehrotra, 1966), Bihar (pahwa and Mehrotra, 1966), Tamil Nadu (Sreenivasan, 1968), Chandigarh (Vasisht, 1968; .Vasisht and Dhir, 1970) and'-Kashmir (Das et al., 1969; Das, 1970).

The number of systematic studies nearly doubled between 1971-980. Vasisht and Battish (1971) contributed four papers dealing with rotifer faupa of North India based on collections from Chandigarb (Union territory) and Patiala (panjab). Nair and Nayar (1971) reported 18 specIes from freshwaters in and around Irinjalakuda (Kerala).

Rajendran (1971) described Conochilus arboreus n.sp. from Madurai while Michael (1913) gave a preliminary account ofrotifers from Tamil Nadu. Nasar (1973) and Laal and Nasar (1971) studied rotifer samples from Bihar. Ten important taxonomic contributions from Andhra Pradesh were made by Ohanapathi which were supplemented by two papers by Chandra Mohan and Rao (1976a, 1977) and Rao and Chandra Mohan (1976a, 1976b 1977). Some studies on the"fauna of Jammu and Kashmir were undertaken by Das and Akhtar (1976), Das (1977), Qadri and Yousuf (1977) and Jyoti and Sehgal (1980). Bhardwaj el al.• (1978) studied a few colonial rotifers from Haryana.

Rotifer systematics in Zoological Survey of India remained unattended after initial publications of Sewell. This work was taken up agai') by this author between 1975-1978 as a research fellow in this institute and resulted in important contributions to the rotifer fauna of West Bengal (Tiwari and Sharma, 1971; Sharma, 1978-1980) 1978c, Himachal Pradesh, HaI'Y.ana and Panjab (Sharma, 1976) and Orissa (Sharffia, 1917, 1980). Later on, Sharma (1980) dealt with 38 species of Eurotatoria feom Assam State in North-Eastern India while Sharma and Michael (1980) presented a synopsis of taxonomic studies on Indian Rotatoria.

The period between 1911-1980 reflected almost same magnitude of ecological information (in tenns of total publications) as in the preceding decade. The studies of Rao and Chandra Mohan (1971),-Oas (1918) and Vasisht and Sra (1979) dealt with pollution indicators. In addition, Vasisht and Sharma (1976, 1977) and Jyoti and Sehgal (1979) made observations on their ecology from Haryana and Jammu respectively. Tiwari and Sharma (1971) commented on changes in species composition of the rotifees in Indian Museum tank, Calcutta •in light of the earlier observations by Sewell (1935). Various other contributions included rotifers in general plankton ecology and these were from Orissa (Saba et al., 1971), West Bengal(Moitm and Mukherjee, 1972; Jana, 1973, 1976, 1979; Sircar and Sen, 1975; Jana et al., 1980; Mondal, 1980), Andhra Pradesh(Seenaya, 1973; Sugunan, 1980), J(ashmir(Das. 1971; Kaul et al., 1978; Zutshi and vass, 1978; Khan and Zutshi, 1980; Zutshi et al., 1980), Bihar (Nasar and Dutta-Munshi, 1974; Nasar, 1977), Madhya Pradesh (Mathew, 1977), Karnataka (Prasadam, 1977), Haryana (Vasisht and Shanna, 1975), Uttar Pradesh (Das and Pande, 1978) and Panjab (Vasisht and Jindal, 1980). The only report of production of rotifers from India was by Nandi et al., (1977) who conducted experiments on mass culture of Brachionus mulleri (=B. plicatil{s) in glass aquaria using common inorganic and organic manures.

There was slight decline in taxonomic studies during the last decade of this review i.e., between 1981-1990. The contributions began with the paper by the author (Sharma, 1981) dealing with 20 species of family Brachionidae from Panjab While later work (Shanna and Sharma, 1984) added 35 species to the fauna of this state. Sharma (1983) reviewed status of Indian species of genus Brachionus and subsequently (Sharma, 1987a) commented on the brachionid rotifers from this country and their distribution. Various other studies by the author and co-worker dealt with rotifers from North-Eastern India and these related to LepadeUa species (Sharma and Sharma, 1987a), Family Notommatidae (Sharma, 1987b), Family Lecanida (Sharma, 1987b), Testudinella species (Sharma, 1990a) and distribution of brachionids this region (Sharma, 1990). In addition, Sharma (1987c) documented 69 species from Orissa State while Sharma and Sharma (1988) reported 35 species of monogononts from Haryana.

A comprehensive account of systematic, distribution and ecology of freshwater rotirer from West Bengal was given by Sharma (1990b). Further, Sharma et al., (1990) documented 55 species of rotifers from Bihar.

Other studies during this period included those from Gwalior (Madhya Pmdcsh) and dealt with faunistics (Saksena and Sharma, 1981a, 1982; Shanna and Saksena, 1981; Saksena and Kulkarni, 1986a), cyclomorphic variations in Brachionus calycij10rus (Saksena and Sharma, 1981), form variations in B..quadridentatus (Saksena and Sharma, 1986) and feeding of Asplanchma brightwelli (Saksena and Sharma, 1984). Saksena (1984) also gave an account of form variations in Indian ~oricate rotifers. A few publications dealing with morphology, colony formation and life-history of colonial rotifers were those by Bhardwaj and Duttagup~1 (1984) and Bhardwaj (1985). Systematic studies on the fauna of Kamataka were attempted by Patil and Gouder (1982, 1989).

The rotifer from lentic and lotic water bodies in and around Patna (Bihar) were examined by Ahmed and Singh (1988) while Misra (1989) reported six species from lentic waters at Bhind (Madhya Pradesh). Sarma (1988) gave an account of27 species (including 25 new records from India) from Kashmir, Delhi and West Bengal.

More attention was focussed on synecology of rotifers during 1981-1990 as reflected by investigations undertaken by Mukhopadhyay et al., (1981); Rao et ale (1981); Qadri and Yousuf (1981, 1982); Yousuf and Qadri (1981, 1986); Balkhi et al., (1984, 1987); Laal (1984); Sandhu et al., (1984); Sharma and Pant (1985); Yousuf et al., (1986); Deb et al., (1987), Haque et al., and Sharma (1990). Additional information was also provided in limnological studies by Patil and Gounder (1985) from Karnataka; Bhattacharya and Saha (1986, 1989) from Tripura, and Khan et. al., (1986) from Uttar Pradesh and Vass el al., (1989) from Kashmir, Some contributions by Sampalh et al' (1981), Sharma (1983, 1986), Outta and Bandhyopadhyay (1985) and Saksena J (1987) dealt with trophic indicator species of rotifers.

So far only publication from this country dealt with karyological studies in this group; Rishi et al., (1983) made these observations in AsplancMa brightwelli.

Recently, studies were undertaken on autoecology, production of mictic and amictic females, production and population dynamics in Brachnionus patulus. The results of these investigations are presented in the publications by Rao and Sarma (1985), Sarma and Rao (1985, 1990, 1990) and Sarma (1989).

Studies from Different Environs

Systematic studies on the rotifers from India commenced in the later part of 19th century but initial progress till 1960's was relatively slow and resulted in only 14 papers (mostly by foreign workers). However, important pre-independence works of Anderson (1889), Murray (1906) and Edmondson and Hutchinson (1934) altogether reported about 150 species; this comprised a significant fraction of total species so far known from this country. A considerable proliferation of faunistic researches were subsequently registered between 1961-1990. As\a result, the present literature on Indian Rotifera is scattered over 105 papers referring to samples from distant localities from the northern latitudes to those from tropical environs of the southern plateau. .

These investigations primarily relate to systematics of freshwater rotifers from the mainland; only a fewer of these works included biogeographical comments on this group. In addition, about 10 publications from this country deal with morphometric variations, fonn variations and cyclomorphosis in some planktonic and semiplanktonic members of the family Brachionidae. Sharma and Michael (1980) presented a synopsis of taxonomic studies on Indian Rotatoria, listed earlier references and remarked on the number of species and genera documented from different States and Union Territories.

The current status of occurrence of rotifer species (fig.) is marginally altered in some states following additional studies in the last decade.

Although various taxonomic investigations were undertaken from scattered localities from different geographical areas, our present knowledge of the freshwater-rotifer fauna of India is still incomplete. This could be attributed to lack of extensive State-Wise or regional faunistic studies based on collections from diversified inland aquatic ecosystems as also highlighted by Sharma and Michael (1980). Further, a good fraction of previous works were focussed on planktonic rotifers only from tropical alkaline water bodies in this country and, therefore, .resulted in localized species inventories and in some cases merely extended local distributional limits of species already reported from India. Moreover, many studies dealt exclusively with new taxa or new records. Earlier literature, ifviewed in terms of number of publications from different states, presents a misleading picture of overall taxonomic contributions.

Till now, eurotatorian fauna of West Bengal is adequately explored and that of Orissa, Punjab, Andhra Pradesh and Jammu and Kashmir is moderately known. Extensive Investigations from different states of this country are still required and some studies are being undertaken by this author and co-workers from various parts of North¬Eastern India and from the states of Orissa and Bihar in Eastern India. Even additional collections from hitherto studied regions are likely to add more rare and interesting taxa this fact is evident from earlier record of 110 species from West Bengal (refer Sharma and Michael, 1980), subsequenlly this figure is presently (Sharma, 1990) raised to 148 species and represents highest diversity so far documented from any particular state of this country. Besides lacunae related to mainland, distant insular freshwater ecosystems of Andaman and Nicobar islands and Lakshnadweep Archipelago remain unexplored; some collections from the fonner group of islands are being examined by the author~

Amongst various freshwater ecosystems, water bodies infested with different assemblages of aquatic macophytcs and rice-fields deserve special mention to examine species composition of their rotifer communities. Michael (1968) listed 30 species of these organisms from a fish-pond of the former category from West Bengal while Sharma (1990) recorded overall diversity of 72 species in these habitats from the mentioned state. In addition, the author (unpublished data) examined 53 species from five such ponds from Bihar. The later biogopes (rice-field ecosystems) are still more interesting as indicated by the records of 30-32 spccies/individual sample from Meghalaya (Shanna and Sharma, 1987) and upto 54 species/single sample from Assam State in North-Eastern region (Sharma, 1987).

A critical analysis of Indian freshwater Rotifera indicates that various planktonic and semi¬planktonic taxa are fairly well documented from this country while periphytic, benthic, colonial,

sessile and bdelloid rotirers are 'still not adequately studied. Morhphometric variations are so far examined in a few brachionid species and could be extended to various other taxa ~ecially based on populations studies from varied geographical areas (under different ecological conditions) and with particular reference to the phenomenon of dwarfing in tropical rotifers (Green, 1977). Some species of the brachionids are known to exhibit ecomorphic variations and these require further analysis from 'various freshwater ecosystems. Taxonomic studies supplemented with information on basic parameters of water quality and aquatic macrophytic associations (if any) are desirable for any fruitful comparison of rotifer communities from different parts of this country. While genetic and biochemical methods remain beyond resources and expertise of most rotifer systematists, detailed SEM studies will serve as valuable adjunct to classical taxonomy and to resolve nomenclatural discrepancies (Koste and Shiel, 1989).

So far only one paper (Murray, 1906) gave an account of mossdwelling rotifers and reflected predominance of bdelloids (27 species) in these biotopes. Additional studies from these interesting habitats, particularly relating to types of moss, will essentially augment otherwise poorly documented digonont rotifer fauna of this country. This generalisation also holds true for soil rotifers (because of abundance of bedelloids) which remain totally unexplored from India. In addition, investigations on psammo-littoral and marine rotifer communities are yet to be initiated. Brackishwater rotifers are practically unknown systematically. Sewell (1934) in his account of fauna of brackish environs of Salt Lakes, Calcutta dealt with species which occurred primarily in fresh waters and indicate euryhaline nature. Some other species of the former category i.e~, Brachionus plicatilis and Tripleucha/anis plicata are also documented from inland waters in this country. However, further investigations need to be undertaken in brackishwater ecosystems to record their characteristic elements.

Limnological studies in India were initiated by Sewell (1935) and since then there has been considerable activity of researches in this field (Michael, 1980; Gulati and Wurtz-Schulz, 1980). Rotifers invariably figure in Indian publications relating to general plankton ecology and were reponed to comprise a dominant or sub-dominant component of freshwater Zooplankto~ic communities. It is not possible to cover all such references within this short review primarily relating to this group. However, about 80 papers from this country provide some worthwhile information on various aspects of seasonal composition, abundance' and ecology of these organisms.

Although this literature dealt with various freshwater ecosystems scattered over futeen/Union territories, a large number of these contributions relate to rotifer communities from tropical fish-ponds or tanks. So far, only about 18 publications dealt exclusively with synecology or rotifer populations. A majority of Indian contributions were made from the states of West Bengal, Jammu and, Kashmir and Uttar Pradesh. A good fraction of these works (Das et al., 1969; Das, 1970; Khan and Zuthis, 1980; Zutshi et 01., 1980; Qadri and Yousuf, 1981, 1982; Yousuf and Qadri, 1981, 1986; Balkhi et al., 1984, 1987; Yousuf et al .• 1986; Das, '1989; Vass et 'ale 1989) referring to their species composition and ecology from Kashmir lakes. Jyoti and Sehgal (1979) conducted investigations in a sub-tropical lake near Jammu while Kumaun lakes were studied by Das and Pande (1978) and Sharma and Pant (1985).

However, there is so far no published report from sub-tropical or temperate lacustrine ecosystems from North-Eastern India. Only fewer investigators (Devassy, 1965; Mathew: 1977; Sugunan, 1980; Bhattacharya and Saha, 1986, 1990) dealt with rotifer ecology from other lakes and reservoirs in this country. Still fewer studies relate to their ecology from riverine ecosystems (Roy, 1955; Ray et al.• 1966; Pahwa and Mehrotra, 1966) while observations in estuaries are those by Dutta et al., (1954) and Shetty et al., (1961).

Rotifers serve as valuable indicators of water quality and rust attempt to designate such species from India was made by Arora (1961. 1966). Some additional information was provided by Rao and Chandra Mohan (1977), Vasisht and Sra (1979), Sampath et al., (1981), Sharma (1983, 1986), Dulta and Bandhopadhyay (1985) and Sakscna (1987). However, a careful examination of regional ecological conditions is necessary before indicators mentioned by these authors are applied to other parts of this country. Slacecek (1983) proposed Q Brr q~otient, and analogen'to various phytoplankton quotients, and could be tried by Indian rotiferologists to establish trophic conditions of individual water bodies or even individual samples.

Considerable attention has been focussed world-wide on intensive culture of rotifers as fish¬food. First attempt in this country was made by Nandy et al., (1977) and dealt with mas rearing of Brachionus plicatilis using common inorganic and organic manures. In addition, recent studies of Rao and Sarma (1985), Sarma and Rao (1981, 1990a, 1990) and Sarma (1989) concerned various aspects of autoecology, population dynamics and production of Braehionus patulus.

The above comments reflected limited infonnation on synecology of rotifer communities in freshwater and esturine environments in general and autecology of individual species in particular. Further studies need to be focussed on species compositions, spatial and vertical distribution, biomass production, popUlation dynamics, effect of predation, eutrophication and acidification on rotifer biocoenosis, trophic indicators and intensive culture of selected freshwater and brackishwater species from this country.

Estimation of Taxa

Out of two subclasses of Rotifera, only subclass Eurotatoria is represented in India and -it is comprised of taxa that generally occur in a wide range of aquatic and semi-aquatic ecosystems while studies on marine forms of subclass Seisona are not yet attempted. Amongst 29 eurotatorian families recognised by Koste (1978),24 families are reported from this country and these include 310 species (345 taxa) belonging to 60 genera. Earlier synopsis by Sharma and Michael (1980), however, dealt with 241 species spread over 21 families and 48 genera.

The presently known species comprise only about 12.4 % of the World's rotifer fauna. Our knowledge of the fauna of this country is certainly incomplete as reflected by lacunae discussed earlier in this paper and any accurate assessment of the fauna is a difficult aspect but a conservative estimate of over 500 species cannot be ruled out. The number of species documented from this country present a notable contrast to the report of 620 species from Australia (~hiel and Koste, 1987) and over 1400 species from Europe (Dum not, 1983). Sudzuki (1989) complied a list of 575 species from the Oriental region and commented on relative richness of the rotifers in the Indian fauna; this conclusion may be misleading unless analysed in view of wider ecological conditions in this country, magnitude of taxonomic publications (about 64 % of examined papers by Sudzuki were from India) and unbalanced information form other countries of this region.

According to Sudzuki (loe. etc.), strangely enough, about 37% of the Oriental rotifers did not appear in India, particular among them was the absence of several tropical species and some cold~water species in its northern territories although their common associates occurred there.

The rotifer fauna of India exhibits greater specific and generic diversity than other South-East Asian faunas (Table 2) and also concerning members of the dominant families. Further, it shows about 60% similarity (vide Sorenson Index) with the rotifers examined from Malaysia and Singapore (Fernando and Zankai, 1981) and lower similarity (about 42%) with the Sri Lankan fauna.

Green(1972), Pejler (1977) and Fcrnando (1980) indicated common occurrence of Braehionus species to be a notable feature of tropical rotirer faunas while predominance of the lacenids (Family Lecanidae) from tropical Australasia was noticed by Dussart et al., (1984). The above generalisations also hold true for the rotirer fauna of India and, therefore, impart it a broadly tropical character. This conclusion is further supported by restricted occurrcnce of temperate species particularly those of NOlholca and Synehaela to the localities in the northern territories of the Kashmir valley.

Cosmopolitan taxa comprise an important fraction of Indian rotifers while cosmotropical,

310 60 tropical and subtropical components are fairly well reported. Endemic elements are represented by 26 species (32 taxa) and comprise abut 9.4 % of the fauna of this country. of these, 14 species belong to Lecane and Lepadella and hence confrrm to the remarks of Dumont (1983) regarding the occurrence of usual endemics of these genera in the fauna of South-East Asia. Overall paucity of Indian endemics in general and that of the family Brachionidae in particular was believed to be secondary and resulted due to loss of characteristic faunal clements afler this subcontinent his Asia (Dumont, loc cit.) and invasion of the Oriental faunal elements to the Near East especially during the Pleistocene. India Srilanka Malaysia &Phillipines Thailand Singapore

Out of the monogonont taxa from the Oriental region, about 51 % are detected from India (Sudzuki , 1989). This review also indicated that they comprise an important component of the fauna of this country and are represented by 281 species (22 families and 55 genera). This super¬order includes two orders i.e., Ploimida and Gnesiotrocha. The former incorporates 239 species (41 genera) while the later is comprised of 41 species (14 genera). The members of Lecanidae, Brachionidae, No tommatidae, Colurellidae and Trichocercidae (in the stated order) from major fraction of the ploimid fauna. The lecanids relate to Lecane-compex including three subgenera (Lecane s. str., Ilemimonostyia and Monostyla). Various endemic•taxa of the family Lecanidae are Lecane (Lecane) lateralis, L.(L.) luna dorsicalis and L. (L.) vasishti from West Bengal; Lecane(Lecane)pawlowski, L. (Monostyla) schraederi and L. (L.) neali from Gujarat; L. (L.)yamunensis from the river Yamuna; L. (L.) sola from Tamil Nadu; L. (L.) donnerianus, L.(L.) bidentata and L. (L.) esWari from Andhra Pradesh and L. (L.) jaintiensis from Meghalaya. The geographical limit of L. pawlowski was extended to West Bengal (Sharma, 1978) while L. lateralis was also examined from Orissa(Sharma, 1987). In addition, L. (L.) Curvilinealis, L. (L.) tesse/ala and L. curvicornis var. padaespares are considered to be apparently identical with L.(L.) curvicornis but type-specimens are not available for comparison.

Endemic taxa of the family Colurellidae include LepadeUa kostei from Gujarat; L. triprojectus. L.ovalis /arga n. comb from West Bengal; L.nartiangensis and L. patella elongata n. comb. from Meghalaya. The mentioned two subspecies were originally described as forms. Family Brachionidae includes Brachionus durgae described by Dhanapathi (1974) from Andhra Pradesh but its status needs to be ascertained(refer: Shanna, 1983). Platyias quadricornis andhraensis is another endemic brachionid documented from this state.

The endemic species of I:he euchlanis (Family Euchlanidae) are Euchlanis brrahmae and Pseudoeuchlanis longipedis from Andhra Pradesh; the later represents a monotypic genus described from this country. Other endemic elements from India include Proales indirae (Family Proalidae) from Gujarat, Ascomorpha saltans indica (Family Gastropodidae) also from the earlier state, Trichocerca tropis from Tamil Nadu and Asp/anchnopus bimavaerensis from Andhra Pradesh.

Order GnesioU'ocha includes suborders Flosculariacea and Collothecacea which are represented by six and two families respectively. Endemic elements of this order are Conochilus arboreus (Family Conochilidae) from Tamil Nadu and C. dossuarius asetosus from Maharashtra, Ptygura stephanion (Family Floscularidae) from West Bengal and another species of this family (Sinantherina triglandularis) from Maharashtra. AnimIJI Resources ofIndia

Fig.l. Map of India indicating number of reported sp ecies Map of India Indicating Dumber of reported species So far about 365 species (21 genera) of digonont rotifers (order Bdelloidea) and belonging to four families are known ~mthe world. Of these, 29 species spread over two Ifamilies and five genera are only documented from India. Endemic elements of bdelloids from this country include monotypic Ps~udoembata described from Tamil Nadu and Rotaria ovata from West Bengal.

Classified Treatment

Sub-Class Eurotatoria

All the rotifer taxa recorded from Indian and this sub continent belong to this subclass which includes freshwater and brackish water forms and is represented by both of its superorder i.e., Monogononta and Digononta.

Super-order Monogononta

Most studies on systematics, distribution and ecology from the Oriental region, nearly 51 % are detected from India,about 40% from Indonesia and Malaysia, approximately 35% from Singapore, 25% from Sri Lanka and about 18% and 16% from Taiwan and Thailand respectively. However,these comprise about 91 % of total 310 species presently docu~ented from this country. A number of important monographs (Voigt, 1957;Rodescu, 1960; Kutikova,1970; Koste,1978) deal with this superorder from different parts of the World while simple identification keys are provided by Edmondson (1959), Ruttner-Kolisko (1974) and Pontin (1978) but a comprehensive treatment from the Oriental region or any of its constitutent countries is yet to be attempted. Both orders of monogonont rotifers (ploimida and Gnesiotrocha) are represented from India. presently

Order Ploimida

This order includes a total of 17 families; of these, representatives of 14 families are reported from this country. However, members of some families have drawn considerable attention in earlier Indian studies.

Family Lecanidae

It is evidently one of the most important families in the rotifer fauna of India is represented by 70% species of the Lecane-complex which includes three subgenera i.e., Leeane s. str., Monostyla and Hemimonoslyla. The publications of Edmondson and Hutchinson (1934), Wulfert (1966), Dhanapathi (1975, 1976) Vasisht and Battish (1971) and Sharma (1978, 1979, 1987) provide valuable information about systematics of the lecanids from this country while knowledge of their ecology is relatively very poor. In view of various discrepancies reflected in our literature, this family needs revision to ascertain correct status of the documented taxa. 11 species (13 taxa) comprise endemic elements in the Indian fauna. Lecane nodosa, L.blachei, L.sinuata and L. thienemanni are apparently confined to Asia while the range of L. bulla diabolica is extended to Central Asia. Various other biogeographically important lecanids from India include Lecanae acronyncha, L. bi/astigata, L.eurvieornis miaminensis, L. hastata, L.lauterborni, L.doryssa, L.haliclysta, L.eiongala. "L.ligona, L.slokesii, L.pusilla, L.syngenes and L.elachis. In addition, L.pertie'a, L.inermis, L.bifurea. L.obtusa, Llurcata, L.perplexa and L.scutata are of local distributional significance. L. nartiangensis, L.dactyliseta. L.doryssa, L.perliea, L.inermis. Ljainliaensis, L.signifera signijera, L.,ligona. L.stokesii and L.seutata are regarded acidophilic elements. Lecane aculeata, L.ludwigi, L.sympoda, L.inopinala, L.quadridentata and L.stenroosi could be termed as wann-stenothermal species.

Family Brachionidae

The members of this family are most extensively studied faunistically and ecologically from India Out of seven genera of this family, four genera are reported from this country. Sharma (1983) gave an account of Indian species of Brachionus and later (Shanna, 1987) commented on

Indian Brachionidae and their distribution. More spr.cies of the genus Brachionus are reported to occur in alkaline water bodies in tropical parts of this country while slightly acidic biotopes particularly in North-Eastern region reflect lesser diversity. Intraspecific variations are documented in Brachionus calysijlorus. B. caudatus and B. quadridentatus while B. falcatus and B. forticula are observed to indicate ecotypic variations. In addition, morphometric variations from this country are studied in Brachionus angularis and observations on cyclomorphosis are made in B.calyciflorus and B. patulus together with the other member of this family i.e., Keratella tropica. B. angularis. B. caudatus, B.calyciflorus and B.rubens are considered as eutrophic indicators in Indian waters while B falcatus and B forficula are known to occur in meso trophic and eutrophic habitats. Brachionus bidentata crassispineus, B.bidentata testudinarious, B.bidentata jirovci, B.donneri, B.patulus mactracanthus. B.pterodinoides and B.sessilis are biogeographically important elements while B. dimidiatus, B.leydigi, B.bennini and B.mirabilis are of local distributional interest. Species of this genus invariably figure in ecological studies from this county and are reported to fonn significant component of planktonic rotifers. Culture of B .plicatilis was attempted in this county by Nandy et al., (1977)and various aspects of autecology of B.patulus were studied at Delhi University by Rao and Sarma. Keratella exhibits lesser diversity than the preceding genus.

Amongst various species reported from this country, K.ticinensis and K. javana are biogeographically interesting; K.lenzi. K.valga and K.procurva show restricted occurrence, K.lropica is widely distributed while K.cochlearis is an important planktonic rotifer in water bodies in North-Eastern India. Genus Anuraeopsis includes only tow species i.e., warm-stenothermal A.coelata and cosmopolitian A.fissa; the later occurs in eutrophic habitats. Amongst species of Platyias, P.leloupi was earlier considered to be aD interesting Ethiopian element but it is now reported (Sharma, 1987) to exhibit pantropical distribution. Notholca included two species which are confined to the northern territories in Kashmit while N.labis is recently reported from the river Yamuna (Sarma, 1988) near Delhi. Kellicottia longispina, a cold¬water species, documented ~rom Sri Lanka is notale for its absence though it is likely to occur in the collections from northern latitudes.

Family Epiphanidae

It has apparently drawn less attention and includes only seven species (four genera); important contributions about their occurrence in this country are by Edmondson and Hutchinson (1934), Dhanapathi (1974) and Sarma (1988). Of the documented species, Epiphanes clavatula and Liliferotrocha subtilis are warm-stenothermal elements.

Family Euchlanidae

This family includes thirteen Indian species belonging to Euchlanis, Dipleuchlanis, Pseudoeuchlanis. Tripleuchlanis and 8cauchampiella and important taxonomic studies on the euchlanids are made by Edmondson and Hutchinson (1934), Dhanapathi (1976) and Sharma (1979d). Amongst Euchlanis species, the boreal E.alala is reported only by Edmondson and Hutchinson (loe cit.) while E.dilalala is widely rcported in plankton coilections from this county. E.triquetra, E.menela and Dipleuchlanis propalula are regarded as acidic water species. Brackishwater Tripleuchlanis plicala is examined from freshwater bodies in Andhra Pradesh (Dhanapailii, 1975) and West Bcngal (Shanna,1979). The monotypic Pseudoeuchlanis is described by Dhanapathi (1975) from Andhra Pradesh.

Family Mytilinidae

Amongst seven species (two genera) of this family known from India Lophocharias oxyslernon, L.salpina and Mytilina mucronala arc examined only by Edmondson and Hutchinson (1934) and L.naias is reported by Wulfert (1966). Mytilina ventralis is mentioned to occur frequently in planktonic and periphytic samples in this country. M. ventralis longidactyla, M. ventralis brevispina and M.acanlhophora are biogeographicaUy important taxa. The cosmopolitan M.bisulcata was reported earlier from peat-bogs (toste, 1978) and has been noticed from a domestic well in West Bengal (Sharma, unpublished); its presence in the potable water is of special ecological-interesL

Family Trichotridae

It includes three species of M acrochaetus which are represented by tropical and subtropical M.sericus and M.collinsi and apparently cosmopolitan M.subquadratus and these occur in periphytic associations. Amongst species of Trichotria, T.pocillium is reported only by Edmondson and Hutcinson (1934) from Ladak while T.tetractis occurs widely in this country. Wolga spinifera was known to be distributed in Eurasia between 37*N-52*N (Koste, 1978); recent report of this species from India (Sarma, 1988), therefore, has considerably extended its distributional nmge.

Family Colurellidae

It comprises an im1'Ortant component (25 species) of Indian ploimid rotifers and is represented by three genera i.e., Colurella, Lepadella and Squatinella. Various works relating to their taxonomic studies from this country are by Edmondson and Hutchinson(1934), Wulfert (1966), Vasisht and Battish (1971), Lepadella ovalis and L.ptella are commonly encountered in planktonic collections while L.aspida and L.aspicora are biogeographically interesting speciers. Various examined taxa from acidic waters in India include Colurella, Sukata, Lepadella triptera, L.nartiangensis, L.patella elobgata, L.cristata and L.dactyliseta.

Family Notomma tidae

This important family of monogonont notifers is not adequately studied in India. It is represented by 26 species of which ten species were reported by Edmondson and Hutchinson (1934) and additional information is provided by Wulfert (1966), Dhanapathi (1975a) and Sharma (1979). Various bigeographically important species recorded from this country are Cephalodella mulea. C.panarisla and Eosphora anlhodis.

Family Gastropodidae

It is so far very poorly documented and most species were listed earlier by Edmondson and Hutchinson (1934) while endemic Ascomorpha saltans indica was described Crom Gujarat (Wulfert, 1966). Gaslropus hyptopus is an interesting species reported from India and is earlier known to be distributed in Europe, Eastern Asia and North America.

Family Proalidae

Amongst four genera of periphytic rotifers included in this family, only genus Proales is represented from India and remains poorly reported (only two species).Of these, P.decipiens is reported only by Edmondson and Hitchinson (1934) while endemic P.indirae is described by Wulfert (1966) from Baroda (Gujamt).

Family Trichocercidae

It is another important family of order Ploimida but includes only 19 species from this country; few valuable contributions dealing with these are by Edmondson and Hutchinson(1934), Wulfert (1966) and Sharma (1979). Trichocerca tropis comprises an endemic species; T.flagellata, described by Hauer (1937) from Tamil Nadu,is now known from Malaysia. T cyllindrica, T bTazieliensis, T slylala and T.rultneri are other biogeographically important members of this family documented from India.

Family Asplanchilidae

It includes predatory rotifers of genus Axplanchna: this genus is represented by widely distributed A. brightwelli which is also regarded as an eutrophic indicator while A. intemtedia and A.pridonta indicate restricted occurrence in this county. Genus Asplancltnopus includes A.multiceps from Ladak, A.hyalinus and A. bimavaraensis from Andhra Pradesh. The only karyological study from India (Rishi et. at., 1983) dealt with Asplonehno brightwelli and indicated acrocentric chromosomes of varying sizes (n = 16, 2n = 32).

Family S ynchaetidae

Various species of genus Synehaeta reported so far from India and two species of Polyarthra i.e., P. euryptera and P.trigla are examined only by Edmondson and Hutchinson (1934). P.longiremis documented by Naidu (1967) from Andhra Pradesh needs confmnation. Arora (1962) described P.multiappendieulata from Nagur and it is a synonym of P.vulgaris (refer: Koste, 1978) which is apparently widely distributed in plankton collections.

Family Dicranophoridae

This is an important family of order Ploimida but remains very poorly studied in India~ So far only six species of genus Dicranophorus and one species o( Eneentrum are documented from this country and infonnation about their occurrence is provided by Wulfert (1966), Dhanapathi (1975) and Shanna (1979). Of these, Dicranophorus epicharis, D.lutkeni and Encentrum longipes are of regional distributional interest.

Order Gnesiotrocha

It is divisible into two suborders i.e., Flosculariscea and Collothecaea which, inturn, include six and two families respectively. All these families are represented in India and contain 42 species belonging to 14 genera. Of these, Floscularidae contains 13 species (6 genera) and taxonomic information about these is primarily given by Anderson (1889), Edmondson and Hutchinson (1934), 'Wulfert (1966) and Sanna(1988). Ptygura stephanion and Sinantherina triglandularis comprise endemic elements. Of the other species, Ptygura tacita is known previously from North and South America while Sinantherrian socialis exhibits pantropical distribution. Some studies on colonialmembers of this family, particularly relating to life-history and colony formation,were undertaken by Bhardwaj and Duuagupta(1984) and Bhardwaj (1985).

Family Conochilidae is relatively poorly documented and included fewer species of genus Conochilus.. of these,C.dossuarius aselosus and C. orboreus are endemic to Indian Rotifera.

Genus Ilexarthra (Family Hexarthridae) includes only four species of which H. bulgarica and H. bulgarica nepalensis are biogeographically important.

Family Filiniidae includes five species of genus Filinia. Amongst these, F. opoliensis, F. longiseta and F. terminalis have frequently been listed in taxonomic contributions from this county. F. pejleri appears to be pantropical in its distribution. In addition, F. cornuta is documented by Sarma(1988) while F. longiseta saltator is examined recently from Bihar(Shanna ft. al., 1990). F. longiseta and F. opoliensis are regarded as eutrophic indicators by various workers from this country.

Family Testudinelljdae is represented by two genera i.e., Pompholyx and Testudinella. The fonner includes two species; of these, P. eomplanata is reported only by Edmondson and Hutchinson (1934) while the later appears to be ofconsiderable importance in plankton collections from various parts of this country. Genus Testudinella is represented by eight species (12 taxa) and amongst these Testudinella "bravieauda, T greeni, T. parva parva, T parva semiparva, T. parva bidentata and T. tridentata are recently documented from India by Shanna (1990).

Horaella brehmi (Family Trochosphaeridae) is a phylogentically interesting species of this family. It was represented earlier from North America, Sri Lanka, Australia, India (West Bengal, Bihar) and its distributional range is currently extended (Koste &Shiel, 1987) to 42* in Tasmania.

Family Collothecidae(Suborder Collothecacea) is represented by four planktonic species which were studied only by Amnderson (1889) from West Bengal.

Another family of the above suborder i.e., A trochidae is represented only by Cupelopagis vorax. This species was documented by Edmondson and Hutchinson (1934) and its male was described by Vasisht and Dawar (1~8). Super-order Digononta Order Edelloidea

All digonont rotifers are included in order Bdelloidea which remains so for very poorly studied from the Oriental region. It is represented by about 365 species belonging to 21 genera; of these, only 29 species spread over five genera known from India. Important taxonomic contributions to the members of the order wete those by Anderson (1889) and Murray (1906); the later dealt with the collections from moss which contained 27 species of bdelloids out of total 32 species examined by Murray. Rotaria rotaria and R. neptunia are occasionally noticed in plankton collections from highly eutrophic water bodies.

Current Studies

Very few specialists are now actively engaged in rotifer systematics in this country. The author and co-worker(Dr. Sumita Sharma, Eastern Regional Station, ZSI, Shillong) are currently studying faunas of the states of Meghalaya and Tripura in North-Eastern India. 'The author is examining collections from Orissa and Andaman and Nicobar Islands and has also initiated studies on the rotifer fauna of Bihar in collaboration with Dr. R.K. Sinha (Patna University). Besides, the author is preparing a monograph of Indian Freshwater Rotifera. An attempt is being made in this department to maintain national reference collections of this group and identification advisory service is extended to research workers of different Indian Universities and institutions. At the moment, some other taxonomic studies are conducted at Jiwaji University (Gwalior) and Kashmir University.

Ecological investigations have been taken up by various workers in routine limnological studies but serious ecological researches are carried at North-Eastern Hill University,Gauhati University, Calcutta University, Kalyani University, Punjab University, Patna University, Aligarh Muslim University, Jiwaji University and Freshwater Biological Station, ZSI, Hyderabad. In addition, investigations on autoecology and production are being attempted at Madurai Kamraj University and Delhi University.

Global studies on the rotirers are, however, much scattered from various classical, aspects to application of latest biotechnological methods. Different fields of these studies include systematics, biogeography, sessile and marine rotifers, community ,structure, ecology, distributional pattems(horizontaI and vertical), population dynamics, competition, effect of grazing and predation, feeding behaviour, escape response, ultrastructure, neuro-ethology, neurophamacology, biochemical aspects with special reference to nutritional value, effect of acidification, fertilization and eutrophication on community structure, bioessay and environmental toxicology experiments, population genetics, development of fast growing strains and intensive culture of rotirers as fish¬food for aquaculture practices.

Expertise India

In ZSI

S.G. PatH, Western Regional Station, Punc. Sumita Sharma, Eastern Regional Station, Shillong. S.V. Muley (Hydcrabad).

Elsewhere

S. Banerjee, &N.C. Dutta, Department of Zoology, University of Calcutta, Ballygunge Circular Road, Calcutta-700019, West Bengal. [Ecology ofplanktonic rotifers].

M.H. Balkhi, Department of Zoology, Govt. Degree College, Baranyka, Jammu and Kashmir. [Seasonal abundance, ecology].

Battish, &H.S. Sehgal, Department of Zoology, Punjab Agricultural University, Ludhiana, Punjab. [Taxonomy and ecology].

Bhattacharya, Department of Life Sciences, Tiripura University, Agartala, Tiripura. [Ecology of planktonic rotifers].

M.V.S.S.S. Dhanapathi, Department of Zoology, DNR College, Bhimavaram, Andhra Pradesh. [Taxonomy, distribution].

S.C. Dey, Department of Zoology, Gauhati University, Guwahati, Assam. [Zooplankton ecology].

B.Y .M. Gouder, Department of Zoology, Karnataka University, Dharwar, Karnataka. [Taxonomy and ecology].

Jana, Department of Zoology, Kalyani University, Kalyani, West Bengal. [Ecology of planktonic rotifers]. Chandra Mohan, Oepartment of Zoology, Andhra University, Waltair, Andhra Pradesh. [Taxonomy and ecology].

M.Y Qadri, Centre for Research for Development, University of Kashmir, Srinagar, Jammu and Kashmir. [Composition and ecological aspects]. C.K.G. Nayar, Department of Zoology, Christ College, Irinjalakuda, Kerala. [Taxonomy and ecology of planktonic rotifers].

Pant, &P.C. Sharma. Department of Zoology. Kumaun University, Nainital, Uttar Pradesh. [Composition and ecology]. Ramakrishna Rao, Department of Zoology. University of Delhi, Delhi. [Autecology, Population dynamics, production].

S.S.S. Sarma, Department of Animal Physiology, School of Biological Sciences, Madurai Kammj University, Madumi, Tamil Nadu. [Autecology, dynamics, production]. D.N. Saksena, School of Studies in Zoology, Jiwaji University, Gwalior, Madhya Pradesh. [Taxonomy, ecology, polymorphism]. B.K. Sharma, &R.G. Michael, Department of Zoology, North-Eastern Hill University, Shillong -793014, Meghalaya [Taxonomy and biogeography of Indian Rotifera, ecology, population dynamics, associations, trophic indicators]. A.R. Yousuf, P.G. Department of Zoology, University of•Kashmir, Srinagar, Jammu and Kashmir. [Composition and ecology]. H.S. Vasisht, Department of Zoology, Punjab University, Chandigarh, Union Territory. [Ecology, morphology , histology].

Abroad

H. Berner-Fankhauser, Zoologisches Institute, Universitat Bern, CH-3012, Bern, Switzerland. [Ecology, population dynamics, effect of sampling intervals].

R. Chengalatb, National Museum of Natural sciences, National Museum of Canada, Ottawa, Canada. [Taxonomy and distribution].

P. Clement, Equipe Neuro-Ethologie, Universite Lyon 1, 69622 Villeurbannc Cedex, France. [Ultrastructure, phylogenesis, Neuro-ethology].

M. V. De Ridder, van Malderlaan, 37/3, B-1710, Diclbeek, Belgium. [Systemayics, ecology, biogeography] .

H. Dumont, Institute of Ecology, State University Gent, B-9000, Gent, Belgium. [Systematic, ecology, indicator value, competitive potential, distribution].

A. Duncan, Department of Zoology, Royal Holloway College, Surrey TW20 9TY, U.K. [Ecology, population dynamics].

W.T. Edmondson, Department of Zoology, University of Washington, Seattle, Washington, U.S.A. [population dynamics, productivity].

Fernando, Department of Biology, University of Waterloo, Waterloo, Ontario, Canada. [Systematics, composition of tropical]. Gilbert, Department of Biological Sciences, Dartmouth College, Hannover, New Hampshire,

[Competition, Predation, Polymorphism, effect of tocopherol]. Green, School of Biological Sciences, Queen Mary College, London, U.K. [Systematics, ecology of tropical rotifers]. Gulati, Limnological Institute, Vijverhof Laboratory, Nieuwersluis, the Netherlands. [Ecology, dynamics, food and feeding]. Herzug, B'iologische Station Neusiedlersee, A-7142, Ikllmitz, Austria. [Ecology, population dynamics]. Hofmann, Max. Plank Institut fue Limhologie, 2320 PIon, Germany. [Taxonomy, ecology, population dynamics].

C.M. James, Kuwait Institute for Scientific Research"Mariculture and Fisheries Department, Salmiye, Kuwait. [Intensive rotirer culture]. King, Department of Zoology, Oregon State University, Oregon, U.S.A. [Population genetics, molecular evolution, adaptations]. Koiste, Ludwig-Brill-Strasse 5, D 4570 Quakenbruck, Germany. [Taxonomy and distribution of monogonoot rotifers].

Kutikova, Zoologivsl Institute of Academy of Sciences, Leningrad B-34, U.S.S.R. [Systematics, ecology, phylogeny, functional morphology]. May, Institute of Terrestruak Ecology, Penicuik, Midlothian, Scotland. [Taxonomy, ecology, dynamics].

Miracle, Dept. Ecol. Fac. Cien. BioI., Universidad de Valencia, Valencia, Spain. [Niche structure in seperate basins, sexual periods, ecology, variability]. Nogrady, Department of Biology, Queen's University, Kingston, Ontario, Canada. [Taxonomy, associations, neuropharmacology]. Pejler, Institute of Limnology, Box 557, Uppsala, Sweden. [Taxonomy, ecology, distribution, trophic indicators, substrate choice].

Pontin, 26, Hermitage Woods Crescot, St. John's Working, Surtey, England. [Distribution, ecology, keys to British Rotifera]. Ricci, Department of Biology, University of Torino, Torino, Italy. [Taxonomy, ecology, biology of bdclloids].

Ruttner-Kolisko, Biologische Station, A-3293, Lunz am See, Austria. [Taxonomy, ecology, population dynamics, metabolism, life-histories].

Shiel, Murray Darling Freshwater Research Station, Albury, N.S.W., Australia. [Taxonomy, ecology, distribution]. T. Snell, Division of Science and Mathematics, University of Tampa, Tampa, Florida, U.S.A. [Isolating mechanisms, genetics, population dynamics]. Starkweather, Department of Biological Sciences, University of Nevada, Las Vegas, Nevada,

[Feeding, Predation]. Sudzuki, Nihon Daigaku, Higashi-Arai, Omiya-shi, I-saitama-Ken, Japan. [Systematics, distrjbution, ecology, affinities].

Turner, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institute, Washington DC, U.S.A. [Taxonomy and distribution]. Wallace, Department of Biology, Ripon College, Ripon, Wisclnsin, U.S.A. [Sessile rotifers, ecology, dynamics].

Selected References

Bartos, E. 1959. Virnici -Rotatoria. Fauna CSR t Prahat 15: 1-969. Donner, 1. 1965. Ordnug Bdclloidea (Rotatoria, Radertiere). Bestimmungsbucher Zur Bodenfauna Europast Licfcrung 6. Akademia Verlag, Berlin. 297 pp.

Edmondson, W. T. 1959. Rotifera. In: Fresh waler Biology (Fds.ll. B. Ward and G. C. Whipple). John Willey &Sons Inc. New York: 420-497.

Edmondson, W. T. &Hutchinson, G. E. 1934. Report on Rotatoria. Article IX. Yale North Indian Expenditition. Mem. Conn. Acad. Artrs Sci., 10 : 153-186. Koste, W. 1978. Rotatoria~ Die Radertiere Mittcleuropas. Begrundet von Max Voigt. Uberordnung Monogononta. Gcbrilder Bomtraeger, Berlin, Stuttart. I. (Textbd: 1-673), II. (Tafelbd: T. 1-234).

Kutikova, L. A. 1970. Rotifer Fauna of USSR. Subclass Eurotatoria (in Russian). Fauna USSR, 104, N<ad Nauk, Leningread. 744 pp.

Ruttncr-Kolisko, A. 1974. Plankton Rotifers. Biology and Taxonomy. Supple Ed. Die Binnengewasser XXVI(I) : 1-146. E. Schwcizerbart sche Vcrlagsbuchranlung, Stuttgart. Sharma, B. K. 1987a. Indian Brachionidae (Eurotatoria : Monogononta) and their distribution. Jlydrobioiogia, 144 : 269-275.

Sharma, B. K. 1987b. Rotifera: Eurotatoria: Monogononta (Freshwater). In: Fauna of Orissa: Slale Fauna Series, 1(1) : 323-340. Publ. by Zoological Survey ofIndia. Sharma, B. K. &Michael, R. G. 1980. Synopsis of taxonomic studies on Indian Rotatoria. I-/ydrobiologia, 73 : 229-236.

Wulfcrt, K. 1966. Rotatoricn aus dcm Status Ajwa und der Trinkwasser"":Aufbercitung der Stadt Baroda (Indien). Limnologica (Berlin), 4 : 53-93.

Voigt, M. 1957. Rotatoria, Die Radcrtierc Mitteluropas. Bcrlin-Nikolasse. I. Textbd (1-508), II. Tafclbd. (T.I-lI5).