Costa, 2010
Rivulus jalapensis, a new killifish from the Tocantins River basin, central Brazil (Cyprinodontiformes: Rivulidae)Rivulus jalapensis, new species, from the Sono River drainage, Tocantins River basin, central Brazil, is described. It is hypothesized to be closely related to R. decoratus from the São Francisco River basin by both species sharing the presence of five branchiostegal rays and small maximum size as adult. Sister group species of the Rivulidae occurring in small sections of the Tocantins basin and in eastern tributaries of the São Francisco River may have been originated by the uplift of the eastern terrains of the São Francisco basin during the early Cenozoic. Rivulus jalapensis is distinguished from all other species of the subgenus Melanorivulus by the color pattern of the unpaired fins in females, in which there are alternating dark gray bars and transverse series of light gray or white round spots. Rivulus jalapensis is distinguished from R. decoratus by the presence of a dark red stripe on the distal margin of the anal fin and the absence of a broad dark gray stripe on the ventral margin of the caudal fin in males.
Wilson J. E. M. Costa
Ichthyological Exploration of Freshwaters, Vol. 21, No. 3, pp. 193-198, 2010