Mangarinus is a genus of gobies native to fresh and brackish waters of Japan, the Philippines, Indonesia, Palau and Micronesia. It is monotypic, being represented by the single species Mangarinus waterousi. This species grows to a length of 4.8cm (01.9inches) SL. The specific name honours the Medical Corps (United States Army) physician Willard H. Waterous (1890-1964) who was a friend of the author, A. W. Herre, and who allowed him to use the Hacienda Waterous on Mindoro, where he collected the type.[1]