Costa & De Luca, 2010
Rivulus cajariensis, a new killifish from the Guiana Shield of Brazil, eastern Amazon (Cyprinodontiformes: Rivulidae)Rivulus cajariensis, new species, is described from the Cajari River drainage, lower Amazonas River basin, northern Brazil. It is hypothesized to be a member of a species assemblage endemic to the Guiana Shield area and adjacent lowlands of Venezuela, diagnosed by the presence of numerous rays in the anal and pectoral fins. The new species is distinguished from all other species of the genus, except R. igneus, by the presence of a dark greenish blue blotch on the upper portion of the opercle, and lower jaw, distal portion of anal fin and lower portion of
caudal fin orange in males. Rivulus cajariensis is distinguished from R. igneus by having fewer scales in the longitudinal and transverse series and by the presence of a black round spot on the upper portion of the caudal-fin base in females.
Wilson J. E. M. Costa and Andre C. De Luca
Ichthyological Exploration of Freshwaters, Vol. 21, No. 4, pp. 353-358, 2010