Pseudacanthicus pitanga is distinguished from its congener (except P. leopardus) by its color pattern with intense orange to red fins (vs. dark background color with white spots in P. serratus and P. fordii or gray background color with black blotches in P. histrix and P. spinosus);distinguished from P. leopardus by the presence of dark blotches anostomosing to form continuous zigzag bands alongside longitudinal keels; absence of blotches on ventral surface of body; faint blotches on head and all fins with orange to red color on unbranched ray and sometimes on subsequent branched rays (dark blotches conspicuous, never anostomosed; large dark blotches on ventral surface; conspicuous dark blotches on head; and red color restricted to dorsal and caudalfin rays); Pseudacanthicus pitanga can be further diagnosed from congeners by the following combination of osteological characters: contact of sphenotic with 6th infraorbital absent, lateral surface of metapterigoid channel triangular (vs. rounded in remaining species), posterior area of contact between cleithrum and coracoid ventrally expanded (vs. straight in remaining species) (Ref. 102632).

Description: Dorsal profile of body slightly convex from tip of snout to vertical through dorsal-fin origin; concave, nearly straight from that point to caudal-fin origin; ventral profile of body straight from snout tip to caudal-fin origin; ventral surface from tip of snout to urogenital papillae lacking plates, except for few small plates at pectoral- and pelvic-fin origins; greatest body width at pectoral girdle; trunk strongly keeled; 5 rows of keels; each one along each body plate series; greatest body depth at dorsal-fin origin, body most slender at caudal peduncle; head tall, pointed anteriorly, somewhat triangular in dorsal view; snout and cheek completely covered by numerous small plates, except for small naked area on tip of snout; snout very pointed in dorsal view; nasal bone rectangular, thin and elongate; frontal bone short, slightly contacting nares anteriorly and orbit posteriorly; anterior margin of frontal short, reaching posterior margin or half nare length; parietosupraoccipital enlogate, its posterior edge narrow, with V-shaped crest; sphenotic short, not contacting IO6, with conspicuous odontodes; orbit small to moderate in size (9,6–16,4% HL), positioned dorsolaterally; iris with small, dorsal flap over pupil; pterotic-supracleithum short, with few fenestrae, its anterior process contacting a small region of posterior margin of orbit; posterior area of pterotic-supracleitrhum with 1 or 2 small sized plates; infraorbital series with 8 pores; infraorbital 4 widely contacting posterior margin of orbit; infraorbital 6 associated with only the posteroventral margin of orbit; lateral line pores restricted to hypural plate; mouth moderate in size, nearly as long as wide; lips large, covered with papillae; size of papillae decreasing towards posterior margin of lower lip; central buccal papilla absent or little developed; upper lip folded over itself; maxillary barbel short; base of barbel united to lips, with free tip; lower lip not reaching anterior margin of coracoid; medial end of premaxillary teeth curved inwards; premaxillae and dentary narrow and elongate; dentary strongly curved inwards; teeth slightly thick, well-developed, with long crown and large lateral cusp; its distal edge slightly curved inwards; 4 to 5 pairs of predorsal plates; cheek plates eversible, with hypertrophied odontodes; dorsal-fin rays i,8, pterygiophores located posterior to neural spines of vertebral centra 6–17; dorsal-fin base very long, its length equals to 12 dorsal plates, reaching pre-adipose plate; connected to adipose fin by thick membrane; dorsal-fin spinelet V-shaped with locking mechanism; 8 furcate neural spines supporting dorsal fin; pectoral and pelvic fins well developed, medial portion conspicuously expanded relative to base; distal margin rounded; pectoral-fin rays I,6; unbranched ray covered with welldeveloped odontodes; tip of adpressed pectoral fin almost reaching vertical through medial, unbranched, pelvic-fin ray; pelvic-fin rays i,5; pelvic-fin spine reaching vertical through anal-fin base when adpressed; anal-fin rays i,4, located posterior to haemal spines of vertebral centra 14–17; caudal fin i,14, i, truncate; caudal fin-ray filaments present in juveniles; supracaudal plates 7; 3 to 5 (usually 4) procurrent caudal-fin rays; 6th rib strongly thickened, remaining ribs slender (Ref. 102632).

Color in life: Dorsal surface of trunk pale brown with median dark blotches that might be faint in juveniles and some adults; dark blotches anostomosing to form continuous zigzag bands alongside longitudinal keels in most specimens; head without well-defined spots or blotches; ventral surface pale, sometimes with some few faint spots

in the abdominal region; spots in general absent in most specimens; all fins with orange or almost red color, at least in the unbranched fin-rays; more evident in the dorsal and caudal unbranched fin-rays; juvenile specimens (in mostcases) with dorsal and caudal fin almost completely faint orange without dark blotches (Ref. 102632). Color in alcohol: specimens in alcohol usually exhibit the same color pattern when live, but in most cases the orange coloration of fins and blotches on body are inconspicuous and faint.