Rivulus robustus, a new cyprinodontid fish from southeastern Mexico

" Five species of Rivulus have been attributed to the Mexican fauna: R. tenuis (Meek, 1904) from Oaxaca, R. myersi Hubbs (1936) from Yucatin, R . hendrichsi Alvarez and Carranza (1952) from Chiapas, R. sp. (Miller, 1966) from Veracruz and Oaxaca and R. marmoratus Poey from Isla Cozumel, Quintana Roo (Goldsiein, 1973). Rivulus hendrichsi was synonymized with R. tenuis by Miller (1966), without comment, but the basis for this action was given by Miller and Carr (1974). The unnamed species of Rivulus referred to above is herein described. It is easily distinguished from the other Mexican species and is sympatric with R. tenuis "