Silver Prochilodus

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

Feeds on plants. Has two stomachs, one filled with mud, probably to digest detritus (Ref. 2059). Juveniles are detritivores (Ref. 51869).

fisheries: commercial; aquarium: commercial

Semaprochilodus taeniurus (Valenciennes, 1817)

Curimatus taeniurus Valenciennes in Humboldt and Bonpland, 1817:166 [type locality: l'Amerique Equioxiale (=Equatorial America), restricted herein to Brazil, Amazonas, upper Rio Negro].—Valenciennes in Cuvier and Valenciennes, 1850:71 [shift of species to Prochilodus].—Taylor, 1964:261 [cited in petition to 1CZN].

Anodus taeniurus.—Müller and Troschel, 1844:84 [fluvio Amazonum (=Rio Amazonas)].

Prochilodus taeniurus.—Valenciennes in Cuvier and Valenciennes, 1850:86 [based upon description in Valenciennes, 1817].—Kner, 1859:148 [comparison with Prochilodus binotatus].—Günther, 1864:297 [based upon Valenciennes, 1850].—Steindachner, 1881a:131 [redescription].—Eigenmann and Eigenmann, 1891:48 [in listing of South American fishes].—Eigenmann and Bean, 1907:667.—Pellegrin, 1909a:148 [Brazil: Tonantins, Santarém].—Eigenmann, 1910:424 [in listing of South American fishes].—Magalhães, 1931:128 [common name, biology].—Bertin, 1947:35 [type depository].—Fowler, 1950:225 [literature compilation]; 1975:360 [literature compilation]. Semaprochilodus taeniurus.—Mago-Leccia, 1972:58 [as recognized species of Semaprochilodus].—Géry, 1977:215 [middle Amazon basin].—Smith, 1981: 43 [fishing methods, relative body size].—Goulding, 1981:39 [migration patterns in middle Rio Madeira].—Junk et al., 1983:406, table 3 [Brazil, Amazon; ecology].—Lowe-McConnell, 1984:143 [economic importance].—Nomura, 1984:58 [Brazil, common name].—Araújo-Lima, 1985:430 [comparisons with other central Amazonian prochilodontids].—Ribeiro, 1985:419 [hybridization with Semaprochilodus insignis].—Araújo-Lima et al., 1986:1256 [exploitation of phytoplankton].—Feldberg et al., 1986:1 [cytogenetics].—Bayley, 1988:131, table 2 [growth rates].—Castro, 1988:504 [compared with Semaprochilodus varii].—Vazzoler et al., 1989:165 [Brazil, Rio Negro basin; reproductive biology], 175 [Brazil, Rio Negro; spawning periods].—Ribeiro and Petrere, 1990:195 [fisheries ecology and management].—Vazzoler and Amadio, 1990:537 [schooling behavior and structure].—Menezes and Vazzoler, 1992:63 [reproductive characteristics].—Ferreira et al., 1998:40, fig. 15 [Brazil, region of Santarém; economic importance in fishery in that region].—Saint-Paul et al., 2000:239, 242 [Brazil, Amazonas, Rio Negro, Lago do Prato; abundance, occurrence in black waters].—Sánchez-Botero and Araújo-Lima, 2001:441 [Brazil, Manaus region; occurrence in aquatic macrophytes].

Semaprochilodus brama [not of Valenciennes, 1850].—Nomura, 1984:58 [Brazil, common name].

Semaprochilodus insignis [not of Jardine, 1841].—Nomura, 1984:58 [Brazil, common name].

Semaprochilodus insignis x Semaprochilodus taeniurus.—Ribeiro, 1985:419 [report of interspecific hybrid].

Semaprochilodus taeniatus.—Petrere, 1989:5 [economic importance at Manaus fish market; species name misspelled].

DIAGNOSIS.—Semaprochilodus taeniurus is distinguished from S. brama, S. laticeps, and S. varii by its lack of the intense dark pigmentation on the membranous opercular border and on the exposed surface of the pectoral girdle that occurs in those three species. Semaprochilodus taeniurus differs from S. insignis and S. kneri, its two congeners that similarly lack dark opercular and pectoral girdle pigmentation, in the number of scales along the lateral line (64 to 77 versus 47 to 53, and 45 to 49 scales, respectively), the number of horizontal rows of scales between the pelvic-fin insertion and the lateral line (12 to 14 versus 9 to 11, and 7 to 9, respectively), and the number of horizontal rows of scales around the caudal peduncle (23 to 26 versus 18 to 22, and 16 to 20, respectively).

DESCRIPTION.—Morphometric and meristic data for Semaprochilodus taeniurus presented in Table 22. Body comparatively shallow and elongate, transversely compressed. Greatest body depth at dorsal-fin origin. Dorsal profile of head gently concave to straight. Predorsal profile of body gently convex; profile posteroventrally inclined along dorsal-fin base; profile ranging from gently convex to straight from posterior of dorsal-fin base to adipose-fin origin and concave along caudal peduncle. Predorsal surface of body with very slightly developed median ridge. Postdorsal portion of body transversely obtusely rounded. Ventral profile of body gently convex from tip of lower jaw to rear of anal-fin base. Ventral profile of caudal peduncle concave. Prepelvic region of body transversely flattened proximate to pelvic-fin insertion. Well-developed median keel extending between pelvic-fin insertion and anus.

Head profile pointed. Mouth terminal. Snout length equal to, or greater than, horizontal width of orbit. Nares of each side of head close to each other; anterior nares circular, posterior nares crescent shaped. Adipose eyelid present and well developed; equally developed on anterior and posterior portions of eye and covering considerable fraction of eye. Lips fleshy, less developed than in Prochilodus and Ichthyoelephas, and forming oral disk when protracted.

Functional teeth in two rows in each jaw. All teeth movably implanted in flesh that overlies jaws. All teeth of similar size, with exposed portions spoon shaped except when worn down. Inner tooth series in each jaw with 7 to 13 teeth on left side of upper jaw and 6 to 10 teeth on left side of lower jaw. Outer row of teeth in each jaw with approximately 55 teeth on each side of upper jaw and approximately 45 teeth on each side of lower jaw in photographed specimen. Upper and lower lips bordered by numerous globular, fleshy papillae.

Scales cycloid. Scales in middorsal series between posterior of dorsal-fin base and adipose-fin origin with spatulate, well-developed, fleshy process along posterior margin of each scale in that series. Lateral line with 64 to 77 (23.1% of specimens with 69) pored scales; 12 to 14 (57.6% of specimens with 13) horizontal rows of scales between dorsal-fin origin and lateral line; 12 to 14 (54.5% of specimens with 13) horizontal rows of scales between pelvic-fin insertion and lateral line; 9 to 11 (57.6% of specimens with 10) horizontal rows of scales between anal-fin origin and lateral line; 14 to 22 (24.2% of specimens with 19) median predorsal scales; 19 to 26 (33.3% of specimens with 20) scales in middorsal series between posterior of dorsal-fin base and adipose-fin origin; 23 to 26 (78.1% of specimens with 24) horizontal rows of scales around caudal peduncle.

Dorsal fin preceded by small, but well-developed, anteroventrally bifurcate, procumbent spine somewhat triangular in lateral view. Dorsal-fin rays (including procumbent spine) iii, 10 [iii,10]; anal-fin rays iii, 8 [iii, 8]; pectoral-fin rays i, 13 to 16 (i, 15 most frequent) [i, 14]; pelvic-fin rays i, 8 [i, 8]; principal caudal-fin rays 10/9 [10/9].

Vertebrae 42 or 43 (81.2% of specimens with 42).

Dorsal fin distally pointed; posterior unbranched and anterior branched rays longest and subequal. Dorsal-fin origin located closer to tip of snout than to caudal-fin base. Greatest length of adipose fin approximately equal to two-thirds of horizontal width of eye. Adipose-fin origin located along vertical that passes through posterior one-third of anal-fin base. Pectoral fin distally pointed. Tip of adpressed pectoral fin reaching posteriorly to, or almost to, pelvic-fin insertion. Pelvic fin falcate. Pelvic-fin insertion located along vertical that passes though anterior one-fourth of dorsal-fin base. Tip of adpressed pelvic fin reaching posteriorly to area approximately one-half of distance between pelvic-fin insertion and anus. Axillary scale present, its length approximately one-third of greatest length of pelvic fin. Posterior unbranched and anterior branched anal-fin rays longest and subequal. Caudal fin bifurcate.

COLORATION IN ALCOHOL.—Ground coloration silvery yellow or yellowish brown, with dorsal portions of body and head darker. Lateral surface of body with approximately 11 to 17 dark, wavy, horizontal stripes along dorsal and ventral margins of exposed portions of scales; 6 to 8 wavy stripes dorsal to, and 2 to 5 wavy stripes ventral to, lateral line; stripes somewhat irregular on caudal peduncle. Diffuse field of brown chromatophores on membranous portion of opercle and on lateral exposed portion of pectoral girdle. Diffuse dark mark on lateral surface of opercle.

Dorsal fin with 2 or 3 (most frequently 3) irregular dark stripes beginning at anterior margin and extending across fin approximately parallel to base of fin. Anterodorsal portion of adipose fin dusky with fine black border. Pectoral and pelvic fins dusky. Anal fin hyaline with fields of dark chromatophores forming 1 to 3 (most frequently 3) (1 stripe reported for holotype by Valenciennes (1817)) irregular, oblique stripes extending across fin, with anterior stripes running in parallel. Occasional specimens lack definite anal-fin stripes. Caudal fin with 5 to 9 (most frequently 6) dark stripes (7 dark stripes reported for holotype by Valenciennes (1817)), 1 stripe overlying middle caudal-fin rays, 2 to 4 (most frequently 3) (3 dark stripes reported for holotype by Valenciennes (1817)) oblique stripes on upper lobe, and 2 to 4 (most frequently 3) (3 dark stripes reported for holotype by Valenciennes (1817)) on lower lobe of caudal fin. Iris reddish brown, with diffusely dusky area on dorsal and ventral portions.

DISTRIBUTION.—Semaprochilodus taeniurus is known from the central portions of Amazon basin and tributary rivers, including the Rio Negro, Rio Branco, Rio Madeira, and Rio Tapajós (Figure 69, stars), that are, with the exception of the last basin, black- and white-water rivers. This species is apparently absent from the clear-water Rio Xingú and Rio Tocantins.

COMMON NAME.—Jaraqui, jaraqui-da-escama-fina (Brazil).

Comparisons.—Semaprochilodus taeniurus is readily distinguished from its congeners by the meristic and pigmentary features cited in the “Diagnosis,” above.

BIOLOGY AND FISHERIES.—Ribeiro and Petrere (1990) provided a summary of the life history and fishery for Semaprochilodus taenurius in the central portions of the Amazon basin. In that region, S. taenurius and S. insignis, both of which are identified under the common name of jaraquis, jointly “dominate 90 per cent of the commercial fisheries” (Ribeiro and Petrere, 1990:208).

MATERIAL EXAMINED.—190 specimens (31, 25.2–281.1 mm SL).

BRAZIL. Amazonas: Rio Maicurú, vicinity of Monte Alegre, NRM 19553, 1. Manaus (3°06′S, 60°00′W), BMNH 1913.7.7:4, 1 (1, 181.0); BMNH 1913.7.25:3, 1 (1, 55.2); MCZ 20134, 2 (223.0–245.0); MZUSP 9578, 1 (198.6); MZUSP 19293, 1 (138.5); NRM 19529, 1; USNM 167826, 1 (1, 179.0); USNM 290145, 1 (1, 208.4) [1R]; USNM 290147, 3 (3, 72.0–84.2). Manaus, Rio Amazonas (3°06′S, 60°00′W), CAS 59322, 3 (1, 197.7–203.1) [3R]; CAS-SU 39296, 3 (2, 134.8–152.3) [3R]. Rio Negro, Manaus (3°06′S, 60°00′W), CAS 6381, 1 (1, 169.8); MZUSP 6680, 7 (132.6–158.0). Igarapé Mauá, Manaus (3°06′S, 60°00′W), MZUSP 4623–4625, 3 (141.6–158.4). Lago do Aleixo, Río Negro, CAS-SU 39294, 1 (1, 216.1); MCZ 20099, 1 (140.0); MCZ 20100, 1 (230.0). Ilha da Marchantaria (3°10′S, 59°45′W), USNM 289798, 2 (2, 114.0–125.7); USNM 290072, 1 (1, 65.2); USNM 290122, 1 (1, 40.4). “Ressaca” on Ilha da Marchantaria (3°10′S, 59°45′W), USNM 290070, 1 (1, 133.6) [1R]. Camaleão, Ilha da Marchantaria (3°10′S, 59°45′W), USNM 290068, 1 (1, 30.7). Ilha da Marchantaria, near Manaus (3°10′S, 59°45′W), USNM 229149, 2 (2, 71.6–77.0) [2R], Reserva Ecológica de Anavilhanas, Rio Negro, Munícipio de Novo Airão, MZUSP 27362, 1 (202.6). Rio Negro, between Manaus and Moura, MCZ 20158, 5 (210.0–235.0). Mouth of Rio Paduaú, Rio Negro, Airão Velho, MZUSP 27363, 5 (138.4–161.6). Pedra do Gavião, Rio Negro, Município de Moura, MZUSP 27365, 3 (144.1–152.1). l'Amerique Equioxiale (=Equatorial America), probably Brazil, Amazonas, upper Rio Negro, MNHN A.8641, 1 (162.1, holotype of Curimatus taeniurus). Rio Solimões, in Tefé and vicinity (approximately 3°24′S, 64°45′W), CAS-SU 39297 (formerly MCZ 20252), 1 (114.6); MCZ 20051, 1 (1, 227.2); MCZ 20102, 3 (157.0167.0). Mouth of Rio Japurá, Rio Solimões, Tefé (3°24′S, 64°45′W), MZUSP 27392, 1 (123.3). Paraná do Lago Aruanã, below Japurá, Tefé (3°24′S, 64°45′W), MZUSP 27364, 4 (86.5–112.3). Manacapuru, Rio Solimes (3°06′S, 61°30′W), BMNH 1925.10.28:64–72, 9(1, 142.0–161.3); NRM 17148, 1; USNM 162816, 1 (150.3; formerly BMNH 1925.10.28:73, in part). Lago Grande de Manacapuru, Manacapuru (3°06′S, 61°30′W), MCZ 20115, 8 (134.0–154.0). Rio Jutaí, tributary to Rio Solimões (approximately 2°31′S, 67°22′W), MCZ 20148, 13 (107.0–124.0); MCZ 20149, 2 (231.0–255.0). Rio Içapó, mouth of Rio Jutaí (approximately 2°31′S, 67°22′W), MZUSP 21024, 1 (262.7). Paraná do Janauacá, entrance to Lago Castanho (3°28′S, 60°17′W), USNM 290069, 2 (2, 25.1–25.2). Lago Janauac´, Rio Solimões (3°28′S, 60°17′W), MZUSP 21562, 4 (178.1–217.2). Paran´ do Janauari, MCZ 20155, 2 (210.0–230.0); MCZ 20156, 2 (166.0–166.1). Tonantins, Rio Amazonas (2°47′S, 67°47′W), MNHN 09.247–252, 6 (1, 115.3–158.2). Rio Tonantins, in Tonantins (2°47′S, 67°47′W), MCZ 20068, 8 (96.0–130.0). Tabatinga, MCZ 20086, 1 (112.0). Fonte Boa, Rio Solimões (2°03′S, 66°01′W), MCZ 20105, 6 (121.0–162.0). Parintins and vicinity (approximately 2°36′S, 56°44′W), MCZ 20127, 4 (159.0–228.0). Lago Coari, Rio Solimões, Coari (4°05′S, 63°08′W), MCZ 20062, 4 (205.0–236.0). Lago Sarac´, in Silves, MCZ 20096, 5 (200.0–224.0). Rio Içá, tributary to Rio Solimões, border between Brazil and Colombia (3°07′S, 67°58′W), MCZ 20112, 6 (135.0–235.0). Rio Maués, Maués, Rio Madeira, MCZ 20074, 3 (145.0–206.0). Jatuarana, Rio Roosevelt, MCZ 20088, 1 (244). Lago Supi´, in front of Codaj´s, MZUSP 9674, 1 (205.2). Itacoatiara, Rio Amazonas, MZUSP 13489–13492, 4 (1, 204.3–230.8). Lago Beruri, Rio Purus (3°52′S, 61°20′W), MZUSP 6378, 2 (157.9–169.8). Par´: Santarém (2°26′S, 54°42′W), MCZ 20078, 4 (203.0–240.0); MNHN 09.63, 1 (1, 224.7). Riacho Urara, tributary of Rio Amazonas CAS 58891, 1 (1, 92.3) [1R], Rio Tapajós, Santarém (2°26′S, 54°42′W), CASSU 58884, 2 (2, 111.0–123.0) [2R], Ilha Japaiuna, Rio Tapajós, MZUSP 21349, 1 (170.5). Porto de Mós, MCZ 20109, 1 (120.0). Óbidos (1°52′S, 55°30′W), MCZ 20139, 8 (139.0–115.0). Rio Tapajós, MCZ 20163, 2 (194.0–198.0). Rio Trombetas, Oriximin´ (1°45′S, 55°32′W), MZUSP 5457, 1 (215.5). Lago Grande, Rio Amazonas, CAS 59321, 1 (1, 131.1). Rondônia: Paraíso, Rio Machado (approximately 3°45′S, 59°03′W), MZUSP 14043, 1 (218.3). Roraima: Rio Branco, beach at Paran´ Marar´, MZUSP 29255, 1 (1, 270.6) [1R]; MZUSP 29261, 1 (1, 281.1) [1R], Inexact Locality: Rio Amazonas, USNM 52545, 2 (1, 237.7); USNM 290375, 1 (220.0).