A NEW SPECIES OXYTRICHA SUSHEELUM N. SP. (CILIOPHORA: SPORADOTRICHIDA) FROM FRESHWATER IN AURANGABAD.

A new species of free living ciliated protozoa, Oxytricha susheelum was recorded from fresh water in Aurangabad, Maharashtra, India. Body shape of O. susheelum n.sp. is ellipsoid with broad posterior and narrow anterior end. Two large, ovoid macronuclei and Adoral zone of membranell running one half of the body length and presence of four to five contractile vacuoles are the distinguishing characters, separating this species from previously described species. INDRODUCTION Protozoa are microscopic organisms. A great diversity of forms is known, they are abundant in aquatic environments and are responsible for consumption and control of bacteria and other microorganism (Finlay, 1997). Protozoan communities could be useful in monitoring the levels of organic pollution in fresh waters (Kolkwitz and Marsson, 1909). Protist excretions are an important source of remineralized nutrients, and of colloidal and dissolved trace meterials such as iron, in aquatic systems (Sherr et. al., 2002). The most common species of genus Oxytricha are O. fallax, O. bifaria, O. ludibunda, O. setigera, and O. lanceolata, which are members of the order Sporadotrichida. All of these species have been found in fresh water only. We report here a previously undescribed species Oxytricha susheelum n.sp. of genus Oxytricha. MATERIAL AND METHODS Water samples were collected in plastic bottles and brought to the laboratory. These samples were then examined under the microscope for further study directly by taking the water drop on a slide which was covered with a cover slip to prevent the drop from drying. Protozoa usually swim rapidly in water and hence are difficult to identify. To immobilize, 10% methyl cellulose was added to the water drop on slide. This slows the movement of organism without immediate death or bursting. Smears are fixed in Schaudinn’s fixative and stained with haematoxylene stain. Description of the genus The genus Oxytricha is first time reported by Bory, 1825. It is a member of class Spirotrichea (Butschli, 1887). In the ciliates of this class cytostome is deep in some and shallow in others. Body is ciliated in some groups but nearly devoid of cilia in others. This genus belongs to family Oxytrichidae and individuals of this family has well developed adoral zone and has cilia or cirri on ventral surface but in some species ventral cirri are reduced while in others, cirri in rows. The organisms of genus Oxytricha have right and left marginals. The organisms of genus Oxytricha have ellipsoid and flexible body. Ventral surface is flattened and dorsal surface is convex. They have 8 frontals, 5 ventrals, 5 anals and short caudals. Marginals may or may not be continuous along posterior body border. Macronucleus is usually in two parts but rarely single or in four parts. These ciliates are usually found in fresh or salt water. Description of the species Present species was collected from fresh water. It is broadly ellipsoid in shape. Anterior end is narrower than the posterior end. Posterior end is broadly rounded. Body measures 63.56µ to 83.99µ in length and 31.78µ to 36.32µ in width. Adoral zone of membranelle (AZM) extends to one-half the body length. Dorsal surface is convex and ventral surface is flattened. 8 frontals, 5 ventrals, 5 anals and short caudals are present. Marginal cirri are confluent at the posterior end. Two large, ovoid macronuclei and 4-5 small, spherical contractile vacuoles were seen in the posterior half of the body.