Gymnotus, Craig & Correa-Roldán & Ortega & Crampton & Albert, 2018

Craig, Jack M., Correa-Roldán, Vanessa, Ortega, Hernán, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, Zootaxa 4413 (1), pp. 111-132 : 128

Key to the Gymnotus of the Upper Madeira based on external morphology

1a. Single laterosensory pore in the posterior corner of the preopercle, cylindrical body profile................. G. coropinae .

1b. Two laterosensory pores in the posterior corner of the preopercle, laterally-compressed body profile................... 2.

2a. Two to three of the anteriormost five pale interbands with both margins crescent-shaped..................... G. chaviro .

2b. Margins of all pale interbands straight or curved in parallel.................................................... 3.

3a. Long, shallow head; pale interbands greater than two-thirds width of dark bands....................... G. c. madeirensis .

3b. hort, deep head; pale bands less than two-thirds width of dark bands............................................ 4.

4a. Laterally compressed body......................................................................... G. eyra .

4b. Sub-cylindrical body.......................................................................... G. riberalta .