GBIF Taxonomic Backbone & Wikipedia Registry Profile
Description. Morphometric data for holotype and paratypes in Table 1. Body compressed. Greatest body depth at vertical through dorsal-fin origin. Dorsal profile of head slightly convex from upper lip to vertical through posterior nostril, straight from that point to tip of supraoccipital spine. Dorsal profile of body slightly convex from latter point to anterior terminus of dorsal fin. Dorsal-fin base straight, posteroventrally slanted, slightly convex from posterior terminus of dorsal fin to adipose-fin insertion and slightly concave between adipose-fin insertion and origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head and body convex from tip of lower jaw to anal-fin origin. Anal-fin base straight, posterodorsally slanted. Ventral profile of caudal peduncle slightly concave. Jaws equal, mouth terminal. Posterior terminus of maxilla reaching vertical through anterior margin of iris. Maxilla approximately at 45 degrees angle relative to longitudinal axis of body. Nostrils close to each other, anterior opening oval, posterior opening crescent-shaped. Premaxillary teeth in two rows. Outer teeth row with 3 bi- to tricuspid teeth. Inner row with 5 bi- to tetracuspid teeth, symphyseal tooth narrower than remaining teeth. Maxilla with 3 (2), 4 (1), or 5 (1) conical to tricuspid teeth. Dentary with 12 (2), 13 (2) or 14 (1) teeth, anteriormost 4 teeth larger, tri- to tetracuspid, 8 – 10 remaining teeth considerably smaller and conical. Central cusp of all teeth more developed than remaining lateral cusps (Fig. 3). Scales cycloid. Two to seven radii strongly marked, circulii well marked anteriorly, weakly marked posteriorly. Lateral line slightly deflected downward and incompletely pored, with 7 * (7), 8 (24) or 9 (5) perforated scales. Longitudinal scales series including lateral-line scales 32 (2), 33 * (6), 34 (5), 35 (8) or 36 (1). Longitudinal scale rows between dorsal-fin origin and lateral line 5 * (35). Longitudinal scale rows between lateral line and pelvic-fin origin 3 * (30) or 4 (5). Predorsal scales 9 * (13), 10 (12) or 11 (8). Circumpeduncular scales 11 (1), 12 * (26) or 13 (1). Caudal fin with few small scales basally. Dorsal-fin rays ii, 9 * (35). Dorsal-fin origin slightly anterior from middle of standard length. First dorsal-fin pterygiophore inserting behind neural spine of 9 th (4) vertebrae. Adipose fin present. Anteriormost anal-fin pterygiophore inserting posterior to haemal spine of 14 th (1) or 15 th (3) vertebrae. Anal-fin rays iv, 18 (2), 19 (22), 20 (23), 21 (5) or 22 (2). Last unbranched and first to third anteriormost branched rays distinctly longer than remaining rays, subsequent rays gradually decreasing in size. Pectoral-fin rays i, 9 (1), 10 (16) or 11 * (17). Pelvic-fin rays i, 7 * (35). Tip of pelvic-fin reaching anteriormost anal-fin rays. Caudal fin forked, lobes roughly rounded and of similar size. Ten (1) or 11 (3) dorsal procurrent caudal-fin rays, and 8 (1) or 9 (3) ventral procurrent caudal-fin rays. Vertebrae 33 (4). Supraneurals 4 (3) or 5 (1), with upper portion wider. Branchiostegal rays 4. First gill arch with 1 (3) or 2 (1) hypobranchial, 8 (1) or 9 (3) ceratobranchial, 1 (4) on cartilage between ceratobranchial and epibranchial, and 3 (1) or 4 (3) epibranchial gill-rakers. Color in alcohol. Overall body color beige. Dorsal portion of head and body darker. Ventral portion of head and body with few scattered dark chromatophores. Snout and dentary tip dark. Dark chromatophores scattered along infraorbitals and opercle, concentrated dorsally. Dorsal scales row dark, with pigmentation more concentrated at center of scales. Three dorsalmost scale rows with conspicuous reticulated pattern formed by dark chromatophores concentrated at scales margins. Area immediately above humeral blotch and middlateral dark stripe clear, with evenly-scattered, light-grey chromatophores. Humeral blotch broad and conspicuous, with diffuse dorsal and welldefined ventral expansions, occupying lateral line scale row and dorsal scale row immediately above, becoming gradually narrower and more diffuse posteriorly. Posterior region of humeral blotch gradually becoming diffuse and coalescing with midlateral dark stripe. Midlateral dark stripe thicker anteriorly, narrowing posteriorly and turning fainter. Dark chromatophores evenly scattered throughout abdominal region. Region above anal fin with dark chromatophores aligned along myocommata of hypaxial muscles. Line of dark chromatophores parallel to anal fin margin at hiatus between end of hypaxial muscles and basis of anal-fin muscles. Caudal fin mostly hyaline, with middle caudal rays with high concentration of dark chromatophores. Anal fin with dark chromatophores scattered along interradial membranes, more concentrated along distal region of anal fin lobe. Dorsal fin ray hyaline, with dark chromatophores concentrated on anteriormost rays. Adipose fin with few scattered dark chromatophores mainly concentrated on proximal region. Pectoral and pelvic fins hyaline. Color in life. Overall body with olivaceous hue, with exception of middle and ventral region of head and abdominal region, with silvery hue. Dorsal portion of eye red. Tricolor longitudinal pattern starting immediately posterior to opercle and ending immediately before caudal fin basis, composed of narrow dorsal red stripe, narrow middle iridescent stripe, and broad ventral dark longitudinal pattern composed of humeral blotch followed posteriorly by midlateral stripe. Longitudinal red stripe anteriorly not continuous, formed by row of red spots, becoming continuous posteriorly and thicker on posterior half of caudal peduncle. Intermediary iridescent stripe golden, relatively narrow and diffuse, thicker anterior to humeral blotch and becoming narrower posteriorly, ending anteriorly to caudal peduncle. Scattered iridescent chromatophores throughout abdominal region (Fig. 2). Variation. Specimens from the rio Abacaxis basin presents a darker color pattern on dorsal region, dorsolateral region and midlateral stripe, and thicker humeral blotch, especially on posterior region, when compared to specimens from the rio Maués-Açu basin. An aquarium raised specimen from the rio Abacaxis basin presented a very dark and longer midlateral stripe when compared to specimen collected from the same locality and fixed immediately after collection (Fig. 2). Sexual dimorphism. Males present tiny bony hooks on distal half of last unbranched anal-fin ray and all branched anal-fin rays (1 to 27), on caudal-fin rays (0 to 9), on distal half of dorsal-fin rays (0 to 17), on all extension of pelvic-fin rays (12 to 53) and on distalmost region of pectoral fin (0 to 2) (all bony hook counts made in a single C & S specimen, INPA 50729, 24.0 mm SL). Bony hooks larger on anterior rays of anal fin and on pelvic fin, observed in INPA 50729 (13, 18.4 – 27.3 mm SL) and INPA 34941 (5, 19.6 – 27.5 mm SL) specimens. Bony hooks of dorsal, caudal and pectoral fins only discernible in C & S individuals. Smaller male presenting bony hooks 18.4 mm SL (INPA 50729). Females reach larger sizes than males (largest female with 29.8 mm SL, largest male with 27.5 mm SL).
