Number of Newly Discovered Rare Species Estimation R package RSE version 1.3 A Bayesian-weighted estimator and two unweighted estimators are developed to estimate the number of newly found rare species in additional ecological samples. Among these methods, the Bayesian-weighted estimator and an unweighted (Chao-derived) estimator are of high accuracy and recommended for practical applications. Technical details of the proposed estimators have been well described in the following paper: Shen TJ, Chen YH (2018) A Bayesian weighted approach to predicting the number of newly discovered rare species. Conservation Biology, In press. Software Youhua Chen <haydi@126.com> Comprehensive R Archive Network (CRAN) Youhua Chen,Tsung-Jen Shen GPL-3 2018-11-20 application/tgz https://CRAN.R-project.org/package=RSE doi:10.32614/CRAN.package.RSE