Biodiversity of freshwater rotifers (Rotifera: Eurotatoria) of Mizoram, Northeast India: composition, new records and interesting features

The plankton and semi-plankton samples examined from Mizoram state of northeast India (NEI) revealed speciose and diverse Rotifera assemblage including a total richness (S) of 162 species belonging to 19 families and 35 genera. The reports of six species new to India, four species new to NEI and 76 new records to Mizoram merit biodiversity interest. The occurrence of one Australasian, one Oriental, seven Paleotropical, one Holarctic, one cosmo (sub) tropical and five other interesting species imparts biogeographical value while several species indicate regional distribution importance. Lecanidae > Lepadellidae > Brachionidae > Trichocercidae collectively comprised 69.7% of total richness (S). Lecane > Lepadella > Trichocerca are diverse genera (~52.0% of S) while Brachionus spp. (~8.0%) deserve cautious mention. The rotifer diversity pattern is predominantly ‘tropical’ with a large component of cosmopolitans (~71.0% of S) while tropicopolitan and pantropical species contributed ~16.0%. This study indicated high richness of the littoral-periphytonic and relative paucity of planktonic taxa. Analysis of periphytic, sessile, colonial and benthic taxa, and of cryptic diversity in certain species-groups merit attention for further biodiversity update and we estimate occurrence of 250+ rotifer species in Mizoram

Zooplankton Diversity of a Soft-water and Highly De-mineralized Reservoir of Meghalaya (Northeast India): The Spatio-temporal Variations and Influence of Abiotic Factors

Hydrobiological survey of a ‘soft-water’ and ‘highly de-mineralized’ reservoir of Meghalaya state of northeast India is undertaken to analyze zooplankton diversity with reference to the spatio-temporal variations and influence of abiotic factors. The littoral and limnetic zooplankton assemblages of this subtropical reservoir without aquatic vegetation reveal total 36 species, and record lower abundance, quantitative dominance of Rotifera, sub-dominance of Cladocera and Copepoda and moderate species diversity. Keratella cochlearis, Bosmina longirostris, Polyarthra vulgaris, Mesocyclops leuckarti, Conochilus unicornis and Asplanchna priodonta influence abundance, species diversity, dominance and equitability of zooplankton. We report differential spatial influence of individual abiotic factors with the relatively more importance at the limnetic region, and the canonical correspondence analysis registers 72.5% and 78.8% cumulative influence of 10 abiotic factors on the littoral and limnetic assemblages, respectively. The spatial differences of various diversity aspects and the influence of abiotic factors suggest habitat heterogeneity amongst the two regions. This study is a useful contribution to zooplankton diversity of the subtropical environs, and soft and de-mineralized waters in particular. Our results mark a distinct contrast to the lowest richness and abundance of zooplankton noted from India vide the preliminary 1990-91 survey of this reservoir

The Indian species of Testudinella (Rotifera: Flosculariacea: Testudinellidae) and their distribution

Our plankton and semi-plankton collections from India revealed 14 species of Testudinella including two undetermined species yet awaiting descriptions. The Oriental endemic T. insinuata is a new record from India while the Australasian T. walkeri and the palaeotropical T. brevicaudata and T. greeni are other globally interesting species. Testudinella amphora, T. brevicaudata, T. dendradena, T. greeni, T. parva semiparva, T. tridentata and T. walkeri are characterized by distribution restricted till date to northeast India (NEI); T. insinuata is restricted to the floodplains of the Kashmir valley of Jammu and Kashmir state of western Himalayas; and T. incisa and T. mucronata are known for valid reports from Tamil Nadu and Jammu and Kashmir, respectively. T. emarginula, T. patina and T. tridentata are believed to be cryptic species-complexes and thus desired ecological and genetic analysis of local populations. This study merits interest vis-à-vis biodiversity and distribution of the Indian Rotifera

The rotifers (Rotifera: Eurotatoria) from the Kashmir Himalayan floodplains and Rotifera biodiversity of Jammu and Kashmir, north India

Our plankton and semi-plankton collections from the floodplain wetlands of the Kashmir valley reveal 140 rotifer species belonging to 43 genera and 22 families. The richness forms ~81% of 173 species, belonging to 51 genera and 23 families, recognized as validly known from Jammu and Kashmir (J&K) vide the present biodiversity evaluation. The rotifer assemblages of the Kashmir Himalayan wetlands and J&K comprise ~33% and ~41%, respectively of the Indian Rotifera; their biodiverse nature is hypothesized to habitat diversity and ecological heterogeneity of aquatic environs of this state of north India. One species is new to India and 25 species are new to northwest India. Lecanidae > Brachionidae form ~33% and Trichocercidae = Lepadellidae > Notommatidae > Euchlanidae comprise ~31% of the rotifer fauna of J&K which includes species of global and regional biogeographic interest and, a large component of cosmopolitan species (~81%). Lecane > Trichocerca > Brachionus = Lepadella collectively comprise ~39%; Keratella > Euchlanis > Synchaeta are notable (~12%); and Notholca and Cephalodella species deserve attention from J&K. Rotifera of the Kashmir Himalayan floodplains and J&K indicate the littoral-periphytic character, cold-water elements, small-sized species, and the relative paucity of Brachionus, Lepadella and Lecane richness. We estimate 260+ rotifer species from J&K pending analysis of intensive latitudinal and longitudinal collections including samples from Ramsar sites, high altitude lakes and other water bodies with emphasis on colonial, sessile and benthic taxa, and analysis of likely cryptic diversity of certain species

Phytoplankton Diversity of a Demineralized Urban Wetland of Meghalaya State of Northeast India: The Spatio-temporal Variations and the Role of Abiotic Factors

The authors analyze phytoplankton diversity of a small urban wetland of Meghalaya to assess biodiversity and limnology interest of small water bodies. This “slightly acidic-circumneutral, demineralized and soft water” subtropical wetland reveals diverse phytoplankton (64 species), indicates high desmid richness and highlights the speciose littoral constellations of up to 55-58 species per sample. Phytoplankton comprises dominant quantitative component of net plankton and registers Charophyta dominance; Chlorophyta > Bacillariophyta > Dinozoa > Chrysophyta > Cyanobacteria depict sub-dominance, and Euglenozoa and Cryptophyta show poor abundance at the littoral and semi-limnetic regions. The richness of phytoplankton and abundance of phytoplankton, Charophyta, Chlorophyta, Dinozoa, Chrysophyta and Cyanobacteria follow bimodal spatio-temporal variations. Closterium, Cosmarium, Staurastrum, Micrasterias, Netrium, Staurodesmus and Scenedesmus are notable genera, and 14 species collectively influence phytoplankton abundance. Phytoplankton registers high species diversity, lower dominance and high evenness. Amongst 15 abiotic factors, only the rainfall and sulphate exert notable influence individually, while the canonical correspondence analysis registers lower cumulative influence of the selected 10 factors on the littoral and semi-limnetic phytoplankton assemblages. This study merits interest for neglected biodiversity and ecology of small aquatic biotopes of India and urban wetlands in particular

Rich freshwater rotifer fauna of small lentic ecosystems of south Andaman, Andaman Sea, India (Rotifera: Eurotatoria)

Small lentic ecosystems are hypothesized to be interesting habitats for metazoan diversity. This study is undertaken to document Rotifera of small freshwater bodies of south Andaman, India. A total of 11 2 species (S), belonging to 32 genera and 19 families, recorded i n our intensive February 2017 collections, indicate rich and diverse assemblage of the taxon. Total richness comprises ~ 27 % of the rotifer species known from India and thus affirms biodiversity interest and habitat diversit y of the sampled habitats. This report adds 42 species, seven genera and three families to the taxa reported till date from freshwaters of the Andaman and Nicorbar islands. Rotifera meta - analysis indicates distinct increase in richness of Lecanidae > Brachionidae > Trichocercidae and tw o - fold increase in Brachionus species. The biogeographically interesting elements comprise 8.0 % of S and several species indicate regional distribution importance. The rotifer fauna shows high richness of cosmopolitan species (~68% of S) and a number of t ropical and subtropical species (~22 % of S). The present study highlights distinct scope to augment Rotifera diversity of the Andaman and Nicorbar islands freshwaters vis - à - vis intensive sampling of varied habitats

Rotifers (Rotifera: Eurotatoria) from floodplain lakes of the Dibru Saikhowa Biosphere Reserve, upper Assam, northeast India: ecosystem diversity and biogeography

This study aims to assess ecosystem diversity of Rotifera of the floodplain lakes (beels) of the Brahmaputra river basin with reference to faunal diversity of the taxon in wetlands of conservation areas of India. We observed 141 rotifer species, belonging to 31 genera and 17 families, from three beels of the Dibru-Saikhowa Biosphere Reserve (DSBR) of Assam, northeast India (NEI) with high total richness (117±2 species) in individual beels. One, two and three species are new to the Oriental region, India and Assam state, respectively and 21 species are globally interesting. The diverse Lecanidae > Lepadellidae > Trichocercidae; the paucity and scarceness of Brachionidae and Brachionus spp. in particular; and rare nature of Keratella, Filinia, Asplanchna, Polyarthra, and Conochilus are salient. The monthly richness and community similarities affirmed heterogeneity in species composition in individual beels while this study exhibited overall rotifer homogeneity amongst beels. The richness followed monthly oscillations in the three beels and lacked significant variations amongst beels. The peak richness of 76 species during summer (May, 2014) from No. 11 beel is one of the richest rotifer assemblages known in single date collection from an aquatic ecosystem of South Asia. Our results explained little influence of individual abiotic factors while canonical correspondence analysis endorsed high cumulative influence of 17 abiotic factors on richness in all beels

Loktak Lake, Manipur, northeast India: a Ramsar site with rich rotifer (Rotifera: Eurotatoria) diversity and its meta-analysis

A total of 162 species (S) of Rotifera belonging to 40 genera and 20 families examined from Loktak Lake, an important floodplain lake of northeast India (NEI) that is one of the richest assemblages of the taxon known from the Indian sub-region. It merits biodiversity value as ~40.0% and ~62.0% of species recorded from India and NEI, respectively. One species is new to India, 23 species are new to Manipur and 14 species are new to Loktak basin. Biogeographically interesting elements included three Australasian, five Oriental, ten palaeotropical and one cosmo-subtropical species. Lecanidae > Lepadellidae > Brachionidae > Trichocercidae collectively comprised 65.4% of S; Lecane > Lepadella > Trichocerca are diverse genera; and paucity of Brachionus spp. is distinct. Loktak Rotifera indicated importance of cosmopolitan, the littoral-periphytonic and small-sized species, and ‘tropical character’. ANOVA recorded significant variations of the rotifer richness amongst three sampling sites of Loktak during June 2010–May 2012 survey. The richness followed osscillaring monthly variations and indicated lack of significant influence of any individual abioitic parameter at all three stations

Ecosystem diversity of Cladocera (Crustacea: Branchiopoda) of the floodplain lakes of Majuli River Island, the Brahmaputra river basin, northeast India

Plankton and semi-plankton samples collected from twelve floodplain lakes (beels) of Majuli River Island of the Brahmaputra river basin, Upper Assam reveal rich Cladocera assemblage of 48 species belonging to 32 genera and 7 families. This report assumes biodiversity value as ~65.0% and ~37.0% of the species, and ~78.0% and ~72.0 of genera of the taxon known from Assam state of northeast India (NEI) and India, respectively. Picripleuroxus quasidenticulatus (Smirnov) is a new record from the Indian sub-region. Biogeographically important elements include one Australasian, three Indo-Chinese and two Oriental species. Total cladoceran richness in individual beels ranged between 16-38 (26 ± 6) species while monthly and seasonal richness in six beels each varied between 8 ± 3-13 ± 3 species and 11 ± 4-17 ± 3 species, respectively and showed lack of any pattern of temporal variations. The community similarities (40.1-86.5% vide Sí¸rensen's index) and the hierarchical cluster analysis affirm heterogeneity in Cladocera composition in different beels. Individual abiotic factors indicated insignificant influence on richness except for significant positive correlation with alkalinity only in Khorkhoria beel

Rotifer assemblages (Rotifera: Eurotatoria) of the floodplain lakes of Majuli River Island, the Brahmaputra river basin, northeast India

Our plankton and semi-plankton collections from twelve floodplain lakes (beels) of Majuli River Island, Upper Assam reveal 124 rotifer species (32 genera and 17 families); these merit biodiversity value as ~52.0% and ~30.0% of species, ~68.0 and ~45.0% of  genera and ~74.0 and ~65.0% of the families of the Phylum known from northeast India (NEI) and India, respectively. Two species are new to India with Trichocerca uncinata as new record to the Oriental region.  Eleven species are new to the study area and we provide an updated list (144 species) for following meta-analyses of Majuli Rotifera. Biogeographically important elements include one Australasian, four Oriental, four Palaeotropical and one cosmo (sub) tropical species while several species are of regional distribution interest. The rotifer fauna is predominantly tropical and Lecanidae > Lepadellidae collectively include ~53.0% species but it records paucity of Brachionus species. Individual beels record total richness of 60-100 (77 ± 12) species, monthly richness between 24 ± 7-34 ± 7 species and maximum up to 54 species/sample. The results are characterized by high community similarities (59.7-90.4% vide Sørensen’s index), more rotifer homogeneity amongst beels, lack of any pattern of temporal richness variations and much limited influence of abiotic parameters