A diagnostic phytolith morphotype found in Porteresia coarctata (Roxb.) Tateoka indicates coastal swampy mangrove environments: A case study from the Indian east coast

Abstract Porteresia coarctata (Roxb.) Tateoka is a true halophytic perennial wild grass that grows profusely along newly formed, highly saline landmasses and mudflats in the coastal mangroves of the Indian subcontinent and acts as a pioneer species in mangrove succession. Comprehensive phytolith analyses on sixteen P. coarctata samples collected from different swampy mangrove locations of four mangrove forests (Sundarbans, Bhitarkanika, Godavari and Krishna) along the Indian east coast show the significant and exclusive presence of a new specialized RONDEL having four distinct horns with flat base (named henceforth as RONDEL FOUR HORNED). Significant numbers of this morphotype have also been recorded in the surface sediment samples collected from these swampy mangrove sites. The RONDEL FOUR HORNED is a diagnostic phytolith morphotype of P. coarctata and a useful indicator of coastal swampy or intertidal mangroves of the Indian east coast. This morphotype was then used to identify past coastal intertidal mangrove environments in a late Quaternary sedimentary profile.