Newly recorded species of Gomphonema (Bacillariophyta) from Hainan Island, China

Five newly recorded species of Gomphonema (Bacillariophyta) are reported from Hainan Island, including Gomphonema jadwigiae Lange-Bertalot & Reichardt, G. pseudoclavatum Lange-Bertalot & Reichardt, G. pseudosphaerophorum Ehrenberg, G. salae Lange-Bertalot & Reichardt, and G. uruguayense Metzeltin, Lange-Bertalot & García-Rodríguez. The morphological characteristics of the five species are described in detail and compared to similar species. This investigation provides basic information for continued algal research in China.