in T. aguarague Fernández & Osinaga and T. taroba. 3) The color pattern of lateral surface of body composed of black blotches over a pale yellow background extending to the mid-length of caudal fin (vs. lateral surface of body gray in T. plumbeus Wosiacki & Garavello and T. papilliferus; with well-defined spots in T. iheringi (Eigenmann); and proximal region of the caudal fin with a vertical unpigmented band in T. diabolus Bockmann, Casatti & de Pinna).
SD: standard deviation. Range, Mean and SD include holotype.
Body relative short, approximately rounded in transverse section at pectoral-fin level and laterally compressed towards tail. Dorsal profile from anterior margin of snout to dorsal-fin origin slightly convex; approximately straight from caudal peduncle to last caudal-fin rays. Ventral profile from tip of snout to pelvic fin slightly convex; straight from this point to last caudal-fin rays. Head relatively small, almost as long as wide, depressed from lateral view and trapezoidal from dorsal view. Snout broad, distal margin slightly convex from dorsal view. Dorsal and ventral profile of head slightly convex.
Eyes dorsally located on head but also visible from lateral view, anteroposteriorly elliptical, covered by thin and transparent skin. Anterior nostril smaller than eye, surrounded by fleshy flap of integument posterolaterally continuous with nasal barbel; distance between anterior nostrils slightly shorter than interorbital distance. Posterior nostril smaller than anterior one, partially surrounded anteriorly, laterally, and medially by thin flap of skin. Posterior nostrils more closely positioned to each other than anterior ones.
All barbels wider at bases and gradually narrowing towards tips. Nasal barbel extending to eye, not surpassing its posterior margin. Origin of nasal barbel on posterolateral margin of integument flap of anterior nostril. Maxillary and rictal barbels extending along cheek to vertical through eye, not reaching interopercular patch of odontodes. Origin of maxillary and rictal barbels on edge of lower and upper lips. Mouth wide, subterminal. Upper and lower lips fleshy, with similar size and bearing large and conspicuous papillae. Lower lip with lateral rounded fleshy lobes. Mental region with small papillae. Gill membranes united to isthmus anteriorly. Nine branchiostegal rays not visible through thick skin. Opercular and interopercular patches of odontodes with 17–19 and 30–34 conic and irregularly arranged odontodes, respectively. Odontodes surrounded by thick integument making smaller ones not visible through skin.
Laterosensory canals with simple (non-dendritic) tubes ending in single pores. Nasal and frontal canals of supraorbital line fused to each other, with three pores (s1, s3, and s6); one paratype with extra pores between pores s3 and s6 on both sides and one paratype with four pores between pores s3 and s6 on left side. Posterior segment of frontal, sphenotic, and otic canals fused to each other. Antorbital segment of infraorbital line absent. Sphenotic canal with two pores (i10 and i11). Otic, postotic and scapular canals with preoperculo-mandibular and pterotic branches short, each one with one associated pore. Trunk canal with 4–7 pores; fourth pore located at vertical through mid-length of pectoral fin.
Pectoral fin with i,7 rays (i,7) and rounded distal margin; third branched ray longest; first one not prolonged as filament. Dorsal fin located posteriorly to mid-length of body and inserted in a conspicuous concavity of dorsal surface of body. Dorsal fin with two or three unsegmented rays; ii,7 (ii,7) with distal margin rounded; first branched ray longest. Dorsal-fin pterygiophores eight, first one inserting anterior to neural spine of 16th or 17th vertebra (16th). Anal fin smaller in size than dorsal fin; anterior insertion located slightly posterior to dorsal-fin base. Anal fin with two unsegmented rays; i,5 rays (i,5) with distal margin rounded; first branched ray longest. Anal-fin pterygiophores six, first one inserting anterior to haemal spine of 21st or 22st verte