"Small Rivulus with long, lanceolate caudal fin, very close in morphology and size, to Riv. ornatus. In the male, flanks dark brown, red or burgundy, with bright yellow-green spots organized in 2 lines in the posterior third of the body. Ventral, anal and dorsal fins yellow to orange. Female devoid of colour, grey, rather lined, with the Rivulus spot at the base of the caudal fin. In both sexes, but especially in the female fairly regular, very contrasting light spots, distributed on each side of the dorsal median. Type E frontal scalation.

The species is easily distinguished, by color pattern, from Riv. ornatus, in which the flanks show red dots on a light background. The size of these two species, less than 40 mm, and their morphology, make them obviously belong to the same group."

This species is endemic to Peru where it is so far known only from its type locality in Quisto Cocha (3°56'S, 72°24'W), 18 kilometres from Iquitos on the Iquitos-Nauta road (Fels and Rham 1981), in the Amazon basin (Ortega et al. 2012). The elevation is approximately 100 m.

Fels, J. F. and P. de Rham 1981 (25 Nov.)
Récentes collectes de Rivulus (Cyprinodontidés) au Pérou, avec description de six nouvelles espèces. Première partie. Revue française d'Aquariologie Herpétologie v. 8 (no. 3): 65-66. [Continues in part 2: Revue française d'Aquariologie Herpétologie v. 8 (no. 4): 97-106.]
https://www.itrainsfishes.net/content/pdf/Fels & DeRahm 1981 6 new Rivulus Peru.pdf

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Richard J. Sexton