Corresponding author: Valter M. Azevedo-Santos (
Academic editor: Peter Bartsch
A new species of the genus
During a taxonomic study of
Measurements were taken following
Institutional acronyms cited in this work are explicited in
Ilustration of two scales (gray color) with arrows indicating the
Humeral spot:
Arrows (red color) indicating the second tooth of the inner row of the premaxilla:
Morphometric data are given in Table
Morphometric data of holotype and paratypes of
Measurements | Holotype | Range | Mean | SD |
---|---|---|---|---|
Standard length (mm) | 52.9 | 41.3–58.3 | 50.2 | - |
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Greatest depth | 47.6 | 41.2–47.7 | 45.1 | 1.6 |
Snout to dorsal-fin origin | 52.8 | 49.6–53.9 | 52.1 | 1.2 |
Snout to pectoral-fin origin | 29.2 | 28.7–31.7 | 30.5 | 0.9 |
Snout to pelvic-fin origin | 53.4 | 50.5–55.1 | 52.5 | 1.3 |
Snout to anal-fin origin | 70.8 | 67.7–71.7 | 70.3 | 1.1 |
Caudal peduncle depth | 11.5 | 10.5–12.3 | 11.4 | 0.5 |
Caudal peduncle length | 8.9 | 8.5–11.2 | 9.3 | 0.7 |
Pectoral-fin length | 23.2 | 21.5–25.6 | 23.5 | 0.9 |
Pelvic-fin length | 20.3 | 17.9–21.9 | 19.8 | 1.2 |
Dorsal-fin length | 33.7 | 31.2–34.4 | 32.8 | 1.1 |
Dorsal-fin base | 16.8 | 14.6–18.7 | 16.0 | 0.9 |
Anal-fin length | 18.7 | 18.6–22.7 | 20.3 | 1.4 |
Anal-fin base | 30.9 | 28.8–31.4 | 30.1 | 0.7 |
Eye to dorsal-fin origin | 36.4 | 34.3–38.8 | 36.7 | 1.1 |
Dorsal-fin origin to caudal-fin origin | 58.4 | 55.3–58.5 | 56.9 | 1.0 |
Head length | 28.1 | 26.3–30.3 | 28.3 | 1.1 |
Head depth | 31.9 | 29.5–33.1 | 31.5 | 1.2 |
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Snout length | 25.8 | 23.2–28.3 | 25.8 | 1.5 |
Upper jaw length | 43.7 | 40.1–47.9 | 44.3 | 2.2 |
Horizontal orbital diameter | 44.9 | 41.4–50.6 | 45.3 | 2.8 |
Least interorbital width | 53.7 | 46.7–57.9 | 52.1 | 3.0 |
Mouth terminal. Posterior tip of maxilla extending beyond vertical through anterior margin of orbit. Premaxillary teeth arranged in two rows; outer row with 4(1), 5*(15) or 6 (1) tricuspidate teeth with central cusp longer; inner row with 5* (17) tetra-to pentacuspidate teeth (Fig.
Dorsal-fin rays ii, 9. Pectoral-fin rays i, 10 (1), i, 11 (10), or i, 12* (6). Pelvic-fin rays i, 7. Anal-fin rays iii, 23 (4), iii, 24 (4), iii, 25* (8), or iii, 26 (1). Adipose fin present.
Scales cycloid with striae curved upward and downward. Lateral line slightly curved, with 30 (3), 31 (6), 32* (6) or 33(2) pored scales. Five transversal scales above lateral line and four transversal scales below lateral line. A single series of scales covering base of second to eleventh branched anal-fin rays. Small scales covering the proximal two-third of caudal-fin lobes.
Total number of vertebrae 32 (2). Gill rakers on lower limb 8 (1); 11* (15); 12 (1); gill rakers on upper limb 7(1), 8(9) or 9*(7). Supraneurals 4 (2).
Overall coloration yellow tan. Concentration of few dark chromatophores on upper lip. Infraorbital and opercular series light silvery due to the scarce remaining guanine pigmentation. Dark chromatophores more densely concentrated along dorsal midline. Sparsely distributed dark chromatophores dorsal of horizontal septum. A dark line marks the horizontal septum. A silvery-gray midlateral stripe extending from posterior margin of humeral spot to caudal peduncle. Irregularly shaped, humeral spot located over third to fifth or fourth to sixth lateral-line scales and extending vertically over three or four horizontal scale rows above lateral line. Paired fins and anal fin hyaline. Adipose with very few dark chromatophores.
Known from the Igarapé da Cachoeira, Içá River, Amazon basin, Santo Antônio do Içá, Amazonas, Brazil (Fig.
Partial map of South America with yellow circle indicating the distribution of
The specific epithet
Aside from an overall similarity in proportions and morphometric and meristic data,
The peculiar upward and downward arched scale
We are grateful to Aléssio Datovo and Michel D. Gianeti (