Apteronotus ellisi (Arámburu, 1957)

Fig. 16

Body elongated and compressed; greatest depth contained 5.8 to 6.2 times in TL; head length 5.9 to 6.5, anal-fin base length 1.1 to 1.2, caudal-peduncle length 6.2 to 7.7, preanal distance 5.8 to 7.2 and prepectoral distance 5.4 to 5.7 in LEA; snout length 2.6 to 3.0, horizontal orbital diameter 12.5 to 18.2 and least interorbital width 3.9 to 4.9 in HL. Mouth terminal. Pectoral fin with 16 or 17 rays, anal fin with 170 to 190 and caudal with 17 to 20 rays (Campos-da-Paz, 1997); transverse series above lateral linte with 5-8 scale rows. Ground color dark-brown dorsally; posterior portion of caudal peduncle and caudalfin base with light-beige blotch. Caudal fin dark-brown.

Maximum total length. 240.0 mm.

Distribution. Rio Paraná-Paraguay basins.

Remarks. Apteronotus ellisi was identified as Porotergus ellisi by Graça, Pavanelli (2007). Albert (2001), in a systematic study of the American knifefishes, proposed a clade named Apteronotus sensu stricto and included A. ellisi .