A new species of Cirolana Leach, 1818 (Isopoda, Cymothoidea, Cirolanidae), from Havelock Island, Andaman Sea, northern Indian Ocean.

Cirolana swaraj sp. nov. was collected from brackish-water Neil Lagoon on Havelock Island, South Andaman and is described and illustrated in detail. Cirolana swaraj sp. nov. can be distinguished by: frontal lamina 2.2 times as long as greatest width, lateral margins slightly widening to rounded anterior margin; pereonite 1 dorsal anterior mid-region with convex boss covered with fine ridges, pereonites 17 each with a single transverse impressed line, posterior margin with 18, 18, 17 and 12 tubercles on pereonites 47 dorsal posterior margins respectively; pleonites 45 each with prominent median tubercle, 4 and 2 tubercules on each side of pleonites 45; pleotelson dorsal surface with sub-median double row of 5 tubercules, posterior lateral margins straight, posterior margin narrowly rounded with 6 robust setae and plumose marginal setae extending anteriorly to mid-length; uropodal exopod lateral margin with eight robust setae and a continuous row of plumose marginal setae. A key to the marine and estuarine genera of Cirolanidae of the northern Indian Ocean is given.

Cassidinidea andamanensis sp. nov., a new species of intertidal Sphaeromatidae (Crustacea: Isopoda) from the Andaman Islands, northern Indian Ocean.

Cassidinidea andamanensis sp. nov. was collected from intertidal habitats on the coast of South Andaman, Andaman Islands, India and is described and illustrated in detail. Cassidinidea andamanensis sp. nov. the second definitive record of the genus from India, is characterized by: smooth body surface, prominently convex epistome anterior margin, pleotelson dorsal smooth surface and the posterior margin is subtruncate and weakly convex with small setae, the appendix masculina posterior margin is narrowly rounded.

Microphytobenthic biomass, species composition and environmental gradients in the mangrove intertidal region of the Andaman Archipelago, India.

Monthly sampling in mangrove intertidal sediments of Andaman Archipelago was carried out during a 1-year study (January to December, 2013) in order to analyse the spatial and temporal distribution of microphytobenthos (MPB) and MPB biomass (sediment chlorophyll-a (chl-a)) in the surficial layer 0-1 cm. The MPB community was mainly composed of diatoms. The MPB biomass concentration in surface sediment (0-1 cm) ranged from 0.7 to 16.98 µg cm-3. Population density of benthic diatoms varied from 78 to 224 ind cm-3. This study identified 41 diatom taxa (27 pennate diatoms, 14 centric diatoms) in the sediment, and among all the diatom taxa, we distinguished few true planktonic species-Coscinodiscus centralis, Coscinodiscus marginatus, Leptocylindricus danicus, Planktoniella sol, Thalassiosira decipiens, Thalassionema nitzschioides and Thalassiothrix longissima. Overall, a high percentage of diatoms were pennate (81%) as opposed to centric. Based on benthic diatom abundance, species composition and distribution, MPB assemblages of sampling stations were grouped into two distinct clusters: one with St. 1 and St. 3 and another one with St. 2 and St. 4. Canonical correspondence analysis (CCA) revealed seasonality as the most important factor determining variability in diatom species composition among sampling sites. There was a distinct seasonal pattern in MPB biomass distribution and benthic diatom cell density during monsoon and post-monsoon seasons. Our results suggest that among various physical and chemical variables studied, greater levels of overlying water nutrients and sediment textures significantly correlated and were conducive factors for MPB. This is the first detailed study on the MPB from these mangrove sediments, providing benchmark data for future studies about these remote groups of Andaman and Nicobar Islands.