Zoological Studies

Vol. 42 No. 2, 2003

Species Diversity of Planktonic and Epiphytic Rotifers in the Backwaters of the Delhi Segment of the Yamuna River, with Remarks on New Records from India

Jyoti Arora and Naresh K. Mehra*

Limnology Unit, Department of Zoology, University of Delhi, Delhi 110 007, India

Jyoti Arora and Naresh K. Mehra (2003) The backwaters of the Delhi segment of the Yamuna River are shallow, weedy, and perennially open lentic habitats that harbor a rich variety of zooplankton, particularly rotifers. The present study is based on planktonic and epiphytic rotifers collected from these backwaters once a month over a period of 1 yr (September 1997 to August 1998). Planktonic rotifers were obtained by filtering water from the littoral zone through a plankton net, while epiphytic specimens were collected from the roots of Eichhornia crassipes and from floating and submerged leaves of Salvinia molesta. In total, 110 species belonging to 39 genera of 20 eurotatorian families were identified. Of these, five species of monogonont rotifers are new records from India, of which 2 are new to the Oriental region. The majority of the species were monogononts, while bdelloids were represented only by Rotaria sp. The largest fraction (76%) belonged to the following families: Lecanidae > Collurelidae > Brachionidae > Trichocercidae > Notommatidae > Flosculariidae. The fauna consisted mainly of cosmopolitan and tropicopolitan taxa except for 3 pantropical, 2 paleotropical, 2 arctic-temperate, 1 eastern hemispheric, and 1 holarctic taxa. The relative composition of planktonic and epiphytic rotifer species as well as the preference of the latter for the roots of Eichhornia compared to the leaves of Salvinia are discussed. Comments are also provided on species of special taxonomic and/or zoogeographic interest.

Key words: Rotifers, Biodiversity, Backwaters, New records, India.

*Correspondence: E-mail: nareshmehra@hotmail.com