RESEARCH ARTICLE Diversification and microscopic structure of tissues in endemic and endangered species of Dawkinsia tambraparniei from the river Tamiraparani, Tamil Nadu, India Divya Sapphire Mohan 1 & Sabaridasan Arumugam 2 & Soranam Ramaiah 1 Received: 13 February 2017 /Accepted: 1 December 2017 /Published online: 19 December 2017 # Springer-Verlag GmbH Germany, part of Springer Nature 2017 Abstract We investigated the study on the endemic and endangered species of Dawkinsia tambraparniei were confined only the areas of the river Tamiraparani. These species are under threats due to the menace of anthropogenic stress. To recognize the crisis behind the particular species, it was analyzed histologically and molecularly from the five pollutant levels of river Tamiraparani. Histologically, the microscopic examinations were also carried out from the crucial organs such as the brain, gill, heart, kidney, and liver, which confirm the spiky survivability of the endemic fish. Assessment of fish organ damages was observed highly in Kokkirakulam and Vannarapettai. Probably with conserved molecular sequences, the species can be identified out from the encountered surveillance of the particular taxa leading to the evolutionary circumstances. The phylogenetic analysis of Dawkinsia tambraparniei populations showed that Cheranmadevi and Vallandau sites populations were closely distributed. Even though the species have similarity sequences of each population were shown that the closely related with same genus but other sub-species. The observed results emphasize the conventional measures to conserve the endemic species and more effectual planning to the proximity of endurances in inhabited zone. Keywords River Tamiraparani . Dawkinsia tambraparniei . Histology . Phylogeny Introduction Recently, momentous consideration has been given to pre- serve our natural ecosystems from the continuous invasion of anthropogenic pollutants that incorporate heavy metals into the freshwater ecosystems (Mendil et al. 2010). Heavy metals from sources such as automobiles, foundry waste, industrial affluence, wearing of metal parts, and equipment are insidious to our environment as they ensues drastic changes on the sediment particles and may saturate the aquatic systems where the vertebrates and non-vertebrates survive (Don-Pedro et al. 2004). For analyzing the biological organization of organs and tissues from the sub-cellular and cellular levels of the popula- tion and community at different ranges, biomonitoring process is inevitable (Pinto et al. 2009; Viana et al. 2013). Estimation of heavy metal accumulation in aquatic organisms is a bioindicator of their impact on the health of organisms and ecosystems. Biomarkers are more proficient than bioindicators as measurements of heavy metal contamination, because they deal with chemical and physiological changes at the organism level and assess contamination based on a direct measure of change in the organism (Lafontaine et al. 2000). For assessing the xenobiotic effects, the histological alter- ations in fish organs are sensitive biomarkers as they emerged earlier for a better evaluation than any other parameters Divya Sapphire and Sabaridasan equally contributed to this work. Responsible editor: Philippe Garrigues * Soranam Ramaiah soranamr@gmail.com 1 Sri Paramakalyani Centre of Excellence in Environmental Sciences, Manonmaniam Sundaranar University, Alwarkurichi, Tamil Nadu 627412, India 2 PG and Research Department of Biotechnology, Sri Vinayaga College of Arts and Science, Ulundurpet, Villupuram District, Tamil Nadu, India Environmental Science and Pollution Research (2018) 25:6570–6583 https://doi.org/10.1007/s11356-017-0896-z