ABSTRACT
Research on cladoceran zoogeography has provided new insights into their distribution patterns, though the Indian subcontinent remains insufficiently studied in this respect. We examine cladoceran distribution patterns on the Indian subcontinent, by addressing their species and body size distribution and beta diversity patterns using species identities as well as body size. We also comment on some interesting and new faunal records from the region. Species occurrence and average body size data were extracted from the literature for certain regions within the Indian subcontinent. Regions were selected based on their location, climatic conditions, and available cladoceran data. Species proportions and average body size were calculated for every region. Faunal differences between regions were assessed by Jaccard’s index and visualized by clustering. We also analyzed and tested differences in beta diversity based on body size. Species composition followed an established trend: Chydoridae were the most species-rich group, followed by Daphniidae. The ratio of Chydoridae to Daphniidae species became lower with latitude. Clustering showed two groups: the northern Himalayan region and the rest of the subcontinent. Dissimilarity was higher in the larger species than in the medium- and small-sized ones, but these differences were not statistically significant. The subcontinent has a mixed fauna with at least four Indian endemics, two species with an Amphi-Pacific disjunction, and many Oriental endemics. Predatory Cladocera are restricted to the high altitudinal Himalayas, while Daphnia subgenus is restricted to latitudes upward of 25°N. A high altitudinal gradient resulting in temperature variances, ecoregion differences and diversity, and potentially predation in combination could be the main drivers of the faunal patterns observed. The subcontinent can thus be divided into an “Oriental tropical zone” and a “High altitudinal temperate zone” for the cladoceran fauna.
