Potamorhina latior (Spix & Agassiz 1829)

Potamodromous. Migrating within streams, migratory in rivers, e.g. Saliminus, Moxostoma, Labeo. Migrations should be cyclical and predictable and cover more than 100 km.

Detritivore (Ref. 76754).

fisheries: minor commercial

Potamorhina latior (Spix)

Anodus latior Spix, 1829:62, pl. 41 [type-locality: rivers of equatorial Brazil].—Müller and Troschel, 1844:83 [Brazil].—Eigenmann and Ogle, 1907:4 [Bolivia].—Eigenmann and Allen, 1942:300 [Peru: Lago Sanango, Río Ucayali, Lago Cashiboya].—Fowler, 1950:276, fig. 333 [compilation]; 1975:362 [reference].—Whitehead and Myers, 1971:495 [proper citation]. [Not Eigenmann and Kennedy, 1903:511; Ringuelet and Aramburu, 1961:36.]

Curimatus latior.—Valenciennes, 1849:19 [Amazon].—Castelnau, 1855:58 [Amazon].—Kner, 1859:145 [Brazil: Rio Negro, Rio Guaporé, Cujaba].—Günther, 1864:293 [Amazon]; 1868:229 [Peru, Zeberos(= Jeberos)].—Steindachner, 1882:136 [Brazil: Teffe (= Tefé), Serpa (= Itacoatiara), Jatuarana].—Eigenmann and Eigenmann, 1889:432 [Brazil: Manacapuru, Hyavary (= Rio Javari), Hyanuary (= Lago Januari), Coary (= Coari), Lago Alexo, Tabatinga, Obidos, Rio Negro, Sao Paolo (= São Paulo de Olivença), Teffe (= Tefé), Serpa (= Itacoatiara)]; 1891:48 [listing].—LaMonte, 1935:7 [Brazil: Rio Purus or Rio Jurua].—Knoppel, 1970:276 [stomach contents].—Lowe-McConnell, 1975:74 [Brazil: Manaus; market fish]. [Not Boulenger, 1896:34; Marelli, 1923:557.]

Curimatus (Semitapicis) latior.—Pellegrin, 1909:148 [Brazil: Tonantins, Tabatinga].

Gasterotomus latior.—Eigenmann, 1910:422 [reference; designation as type-species of Gasterotomus].—Starks, 1913:14 [Madeira River].—Fowler, 1939:257 [Peru: Contamana]; 1945:120 [listing].—Smith, 1981:140 [Brazil: Itacoatiara fishery]. [Not Ringuelet et al., 1967:196; Roberts 1974:433].

Semitapicis laticeps.—Fowler, 1945:256 [in part; Peru: Ucayali River].

Gasterostomus latior.—Fernandez-Yepez, 1948:34, fig. 14 [incorrect spelling, listing].—Ovchynnyk, 1968:250 [Ecuador].

Curimata (Gasterotomus) latior.—Géry, 1977:234 [reference in part, not La Plata basin].—Junk et al., 1983:406 [Brazil: Ilha de Marchantaria; seasonal occurrence].

Curimata latior.—Goulding, 1981:39, 45, 60, 105, fig. 37 [migration, fisheries, common name]. [Not Berg, 1899:93.]

Semitapiscis latior.—Braga and Azpelicueta, 1983:148 [in part, Amazonian citations; not La Plata Basin records].

DIAGNOSIS.—A moderate-sized Potamorhina species reaching 205 mm SL. Potamorhina latior is readily distinguished in having 36 to 37 vertebrae contrary to 31 to 35 in its congeners. Externally the highly developed median preventral keel continuous with the distinct, nonserrate postventral keel distinguishes P. latior within the genus. Potamorhina pristigaster, in contrast, has a transversely flattened or slightly concave, laterally keeled preventral region and a serrate median postventral keel. In P. laticeps and P. squamoralevis the ventral keel anterior to the pelvic fin insertion is not so highly developed. Potamorhina altamazonica, in turn, has the ventral body surface anterior to the pelvic fin insertion smoothly rounded transversely.

DESCRIPTION.—Body elongate, compressed, more so in specimens over 150 mm SL. Dorsal profile of head straight. Dorsal profile of body smoothly convex from rear of head to origin of rayed dorsal fin; straight and posteroventrally slanted at base of dorsal fin, straight or very gently convex from base of last dorsal-fin ray to dorsal margin of caudal peduncle. Dorsal body surface with an indistinct median keel anterior to rayed dorsal fin, smoothly rounded transversely posterior to fin. Ventral body profile slightly convex from tip of lower jaw to anteroventral portion of pectoral girdle, distinctly convex from that point to vertical through pelvic fin insertion, slightly convex from pelvic fin insertion to ventral margin of caudal peduncle; prepelvic convexity more pronounced in larger specimens. Prepelvic region with a well-developed, acute, median keel that extends from anteroventral margin of pectoral girdle to area between insertion of pelvic fins; keel more pronounced in larger specimens. A well-developed median keel between pelvic fin insertion and origin of anal fin. Pre- and post-pelvic keels continuous, pelvic fin insertion distinctly dorsal of midvental line.

Greatest body depth at origin of rayed dorsal fin, 0.32–0.40; snout tip to origin of rayed dorsal fin 0.45–0.50; snout tip to origin of anal fin 0.73–0.82; snout tip to insertion of pelvic fin 0.48–0.55; snout tip to anus 0.71–0.79; origin of rayed dorsal fin to hypural joint 0.54–0.63. Rayed dorsal fin pointed, less so with increasing age; anteriormost rays 2.6–3.0 times length of ultimate ray. Pectoral fin pointed; length of pectoral fin 0.15–0.19; fin extends two-thirds to three-quarters distance to vertical through insertion of pelvic fin; relatively longer in juveniles. Pelvic fin pointed, length of pelvic fin 0.17–0.25; fin reaches three-quarters of distance to anal fin origin. Insertion of pelvic fin distinctly dorsal of midventral margin of body. Caudal fin forked. Adipose fin well developed. Anal fin margin straight or slightly concave, anteriormost branched anal rays twice length of ultimate ray. Caudal peduncle depth 0.10–0.11.

Head distinctly pointed in profile, head length 0.28–0.37; jaws equal, mouth terminal; snout length 0.26–0.32; nostrils of each side very close, anterior circular, posterior crescent-shaped with aperture closed by thin flap of skin that separates nares; orbital diameter 0.20–0.26; adipose eyelid present, highly developed anteriorly, with a vertically ovoid opening over center of eye; postorbital portion of head elongate, length 0.48–0.58; gape width 0.27–0.34; interorbital width 0.42–0.47.

Pored lateral line scales from supracleithrum to hypural joint 83 to 105; all scales of lateral line pored, canals in scales diverge dorsally and ventrally in adults; 5 to 11 series of scales extend beyond hypural joint onto caudal fin base; 18 to 22 scales in a transverse series from origin of rayed dorsal fin to lateral line, 16 to 20 scales in a transverse series from the lateral line to origin of anal fin. Scales weakly ctenoid, ctenii most developed in prepelvic region.

Rayed dorsal-fin rays ii,9–10; anal-fin rays ii,11–14 or iii, 12–13; pectoral-fin rays 14 to 18; pelvic-fin rays i,8.

Color in Alcohol: Overall coloration silvery-golden to silvery-brown, head and body pigmentation more intense dorsally. All fins with small chromatophores that outline fin rays; distal portion of middle rays of caudal fin dusky in some individuals.

DISTRIBUTION.—Rio Amazonas drainage basin (Figure 17).

COMMON NAME.—Brazil: Branquinha chora (Goulding, 1981).

MATERIAL EXAMINED.—455 specimens (89, 63.9–205.1)

BRAZIL. Pará: Rio Tapajós, Santarem, MZUSP 5719, 3 (1, 149.3). Rio Tapajós, CAS uncat., 1 (102.8). Rio Maica, Santarem, MZUSP 9172, 1 (187.5). Santarem, CAS uncat., 1 (116.5); CAS uncat., 1 (114.0); CAS uncat., 1 (92.0). Óbidos, MCZ 20236, 10 (2, 130.3–142.0). Rio Trombetas, Oriximiná, MZUSP 5418, 28 (5, 139.8–171.0). Lago Parú, Oriximiná, MZUSP 5595, 6 (2, 174.5–187.3). Paraná Jacare;, Faro, MZUSP 7823, 3 (1, 133.0). Amazonas: Jatuarana, MCZ 20342, 3 (169.7–173.5); NMW 68842, 1; NMW 68843, 1. Rio Purus, AMNH 12507, 1 (109.0). Lago Beruri, Rio Purus, MZUSP 5998, 12 (3, 122.3–183.6); MZUSP 6372, 8. Mouth of Rio Purus, MZUSP 5947, 17 (3, 125.1–174.5); MZUSP 5953, 2; MZUSP 5952, 1. Rio Jurua, AMNH 12552, 1 (195.0). San Paolo (São Paulo de Olivença), MCZ 20223, 3. Manacapuru, MCZ 20207, 2 (158.5–160.0); BMNH 1975.10.28:62, 1. Lago Manacapuru, MZUSP 6521, 1. Lago Jacare; above Manacapuru, MZUSP 5904, 5. Rio Madeira, CAS-SU 22068, 1 (165.4). Tabatinga (Sapurana), MCZ 20246, 1 (148.3). Rio Negro, MCZ 797, 2 (130.2–146.6); NMW 68840, 1. Manaus, MZUSP 5834, 4; MZUSP 6130, 3; CAS uncat., 1 (175.0); GC, 2; BMNH 1929.11.18:9, 1; BMNH 1970.4.2:9, 2. Mouth of Rio Negro, NMW 68839, 1. Vicinity of Manaus, USNM 228692, 1; USNM 228691, 3; USNM 228690, 5. Rio Madeira 7 km E of Humaita, GC, 1. Fonte Boa, MCZ 20265, 1. Igarape Manduaçu, Paraná de Iupia, NW of Fonte Boa, MZUSP 20963, 37. Lake Hyanuary (= Lago Januari), MCZ 20269, 2; MZUSP 6866, 26. Tefé, MCZ 20256, 5. Lago Grande, CAS uncat., 1 (159.1). Serpa (= Itacoatiara), MCZ 20319, 19; MZUSP 13483–86, 4 (2, 165.1–188.7); NMW 68844, 5. Urucará, Paraná de Urucará, MZUSP 7513, 4 (2, 130.7–166.5); MZUSP 5761, 2. Lago Janauacá, MZUSP 21559, 18 (5, 190.0–205.1); MZUSP 21696, 3. Lago Supia near Codajás, MZUSP 9664, 8 (3, 150.7–159.3). Rio Solimões near Ilha Baruruá, above mouth of Rio Jutai, MZUSP 20982, 3. Lago Pauraquequara, mouth of Rio Pauraquequara, MZUSP 6088, 1. Rio Madeira, 25 km from Nova Olinda, MZUSP 6954, 11. Mouth of Rio Pacia, MZUSP 21484, 2. Acre: Mouth of Rio Moa, Cruziero do Sul, ZUEC 419, 1. Rondônia: Rio Machado, USNM 220196, 7 (178.0–226.0). Rio Machado, Lago do Paraiso, USNM 242144, 3.

BOLIVIA. No specific locality, USNM 44836, 1 (112.5). Beni: Río Mamoré, 5 km SE of Limoquije, AMNH 43053, 1 (130.0); AMNH 48868, 7. Río Mamoré W of San Pedro, AMNH 48676, 11, (64.6–97.5); AMNH 43050, 67. Puerto Siles, AMNH 43051, 1. Boca del Río Ibarre, AMNH 43054, 2; AMNH 43052, 21. Río Mamoré 5 km W of San Javier, AMNH 48677, 3 (1 specimen cleared and counterstained for cartilage and bone).

PERU. Loreto: Lago Sanango, CAS-IU 15822, 2 (144.0–151.7); CAS-IU 15666, 3 (142.0–156.0). Lago Cashiboya, CAS-IU 17864, 2 (87.5–110.0). Contamana, CAS-IU 17863, 3 (169.0–190.0); ANSP 73166, 1 (103.0); ANSP 73167, 3 (81.0–164.7). Tuye Cocha, USNM 175841, 1 (139.5). Río Samiria, Atum Cocha, MZUSP 15241, 2 (1, 140.0). Amazonas: Ayambas, LACM 36342-4, 1. Ucayali: Vicinity of Pucallpa, AMNH 35687, 1 (86.8); AMNH 48673, 3. Yarinacocha, AMNH 48674, 1 (81.3).

COLOMBIA. Amazonas: Near Leticia, ANSP 135974, 12.

Amplamente distribuída na bacia do rio Amazonas.