Description:-

Frustule with short pervalvar axis. Valve circular, flat, 19 to 218 mm in diameter, with rounded margins and shallow mantle, with one to two rows of areolae. Central area variable, with indistinguishable rosette or conspicuous rosette of larger areolae surrounding a more or less developed hyaline area. Areolar pattern irregular in the smaller specimens to radial, forming spiralling decussate arcs, in the larger specimens. Cribrum simple, without subsidiary areas of perforation, with concentric rings of larger poroids at the periphery. Cribra confluent at the valve mantle. Marginal ring of microrimoportulae including two macrorimoportulae. Microrimoportulae, two to three in 10 mm, shortly pedicellate, tubular, slightly opening by a slit inside and by small circular apertures outside. Macrorimoportulae noticeably larger than microrimoportulae, with long thick neck, slightly wider at the top than at the base, trilobulate, curved toward the mantle, opening internally by a slit. Cingulum composed by three open bands, a wide valvocopula and two narrower copulae.

Threats:-

Not recorded

Remark:-

Kadinamkulam Backwater (NIO database, biosearch).

Habitat:-

Brackish water

Synonyms:-

References:-

Hasle, G.R. & Syvertsen, E.E. (1996). Marine diatoms. In: Identifying Marine Phytoplankton. (Tomas, C.R. Eds), pp. 5-385. San Diego: Academic Press.
Guiry, Michael D. (2015). Coscinodiscus radiatus. In: Guiry, M.D. & Guiry, G.M. (2015). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway (taxonomic information republished from AlgaeBase with permission of M.D. Guiry). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=149158 on 2015-04-27
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