Imparfinis, Silva & Reia & Morimoto & Benine & Oliveira, 2023

Silva, Gabriel S. C., Reia, Lais, Morimoto, César K., Benine, Ricardo C. & Oliveira, Claudio, 2023, Integrative taxonomy of Imparfinis (Siluriformes, Heptapteridae) from the Upper Paraná River basin, Brazil, with description of a new species, Zootaxa 5249 (3), pp. 357-377 : 372

Key to Upper Paraná basin species of Imparfinis

1. 11−12 gill rakers on first ceratobranchial; conspicuous longitudinal dark stripe along flank; first dorsal-fin ray longer or approximately of same length of second ray........................................................ I. schubarti

1’. 5−7 gill rackers on first ceratobranchial; inconspicuous longitudinal dark stripe along flank; first dorsal-fin ray shorter than second ray;.......................................................................................... 2

2. Orbital diameter 11.8−19.9% in HL; caudal peduncle depth 8.0−12.2% in SL................................. I. mirini

2’ Orbital diameter 20.0− 25.5 in HL; caudal peduncle depth 5.3−7.6 in SL.......................................... 3

3. 39−40 vertebrae, 7−8 gill rackers on first ceratobranchial, body uniformly colored.......................... I. piperatus

3’. 38 vertebrae, 5−6 gill rackers on first ceratobranchial, body mottled colored............................... I. lepturus