Curimata knerii Steindachner 1876

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

Curimata knerii Steindachner

Curimatus knerii Steindachner, 1877:83 [type locality: Tefé]; 1882:135 [in part, Tefé, mouth of Rio Negro; not Rio Branco and Surinam].—Eigenmann and Eigenmann, 1889:428 [Brazil: Montalegre (= Monte Alegre), Porto do Moz, Rio Negro, Tonantins, Lake Hyanuary (= Lago Januari)]; 1891:47 [reference].—Eigenmann, 1910:422 [reference]. [Not Eigenmann and Ogle, 1907:4].

Curimatus macrops.—Eigenmann and Eigenmann, 1889:430 [one specimen from San Paolo (= Saõ Paulo de Olivença)].

Curimata knerii.—Fernández-Yépez, 1948:38, fig. 17 [reference].—Fowler, 1950:286 [references in part, not Surinam records]; 1975:369 [reference].—Goulding et al., 1988:132 [Brazil, Rio Negro, Anavilhanas; detritivory].—Vari, 1989, tables 2, 3 [phylogenetic relationships].

Curimata kneri.—Géry, 1977b:230 [in key, Rio Negro].—Ortega and Vari, 1986:11 [Peru; common name].—Bayley, 1988:131 [Brazil, Rio Amazonas, near Manaus; detritivory, growth rates].

DIAGNOSIS.—The combination of a body depth 0.40–0.47 of SL, 7 to 9 branched anal-fin rays, and the lack of any marked body pigmentation pattern distinguishes Curimata knerii from all other members of the genus with the exception of C. cyprinoides and C. roseni. Curimata knerii has 33 or 34 vertebrae, 56 to 63 pored lateral-line scales, and 15 to 17 enlarged median prepelvic scales. This contrasts with 31 vertebrae and 12 to 24 enlarged median prepelvic scales in Curimata roseni and typically 32, rarely 31 or 33, vertebrae and 46 to 56 lateral-line scales in C. cyprinoides. Curimata knerii and C. cyprinoides have overlapping lateral-line counts, but demonstrate significantly different modal values for that meristic value (Figure 29).

DESCRIPTION.—Body moderately elongate, somewhat compressed. Dorsal profile of head straight or very slightly concave in smaller individuals, straight in larger specimens. Dorsal profile of body distinctly curved from rear of head to origin of rayed dorsal fin; straight or slightly convex, posteroventrally slanted at base of dorsal fin, gently convex from base of last dorsal-fin ray to caudal peduncle. Dorsal body surface with an indistinct median keel anterior to rayed dorsal fin, smoothly rounded transversely posterior to fin. Ventral body profile nearly straight from tip of lower jaw to region of vertical through middle of pectoral fin, more convex from that point to origin of pelvic fin, then somewhat sigmoid to caudal peduncle. Prepelvic region flattened, margined laterally by distinct, nearly right, angles in body wall. Prepelvic region with median series of enlarged scales flanked on each side by series of enlarged scales that conform in shape to lateral angle of body. Well developed median keel posterior to pelvic fin origin with secondary obtuse angle in body about two scales dorsal of ventral midline on each side of postventral portion of body.

Greatest body depth at origin of rayed dorsal fin, depth 0.38–0.44 [0.41]; snout tip to origin of rayed dorsal fin 0.48–0.53 [0.51]; snout tip to origin of anal fin 0.79–0.84 [0.82]; snout tip to origin of pelvic fin 0.52–0.56 [0.52]; snout tip to anus 0.75–0.80 [0.79]; origin of rayed dorsal fin to hypural joint 0.54–0.60 [0.60]. Rayed dorsal fin pointed, anteriormost rays filiform in some individuals, reaching to tip of dorsal rays of dorsal lobe of caudal fin. Pectoral fin pointed; length of pectoral fin 0.19–0.24 [0.22], extends to or slightly short of vertical through origin of pelvic fin in smaller adults, falls short of that line in largest specimens examined. Pelvic fin pointed, length of pelvic fin 0.19–0.26 [0.23], reaches three-quarters of distance to origin of anal fin. Caudal fin forked. Adipose fin well developed. Anal fin emarginate, anteriormost branched rays three to four times length of ultimate ray. Caudal peduncle depth 0.11–0.13 [0.12].

Head distinctly pointed, head length 0.28–0.33 [0.30]; upper jaw longer, mouth inferior; snout length 0.26–0.34 [0.30]; nostrils of each side of head very close, anterior circular, posterior crescent shaped with aperture closed by thin flap of skin that separates nares; eye relatively large, orbital diameter 0.29–0.35 [0.30]; adipose eyelid well-developed, particularly in larger specimens, with vertically ovoid opening over center of eye; length of postorbital portion of head 0.38–0.43 [0.42]; gape width 0.27–0.34 [0.27]; interorbital width 0.42–0.48 [0.44].

Pored lateral-line scales from supracleithrum to hypural joint 56 to 63 [59]; all scales of lateral-line pored, canals in scales straight; 5 to 8 series of scales extend beyond hypural joint onto caudal fin base; 14 to 16 [15] scales in transverse series from origin of rayed dorsal fin to lateral line; 9 to 11 [9] scales in transverse series from the lateral line to origin of anal fin. Median series of enlarged prepelvic scales 15 to 17.

Dorsal-fin rays ii or iii,9 [ii,9]; anal-fin rays ii,7–9 or iii,8–9 [ii,8]; pectoral-fin rays 13 to 17 [15]; pelvic-fin rays i,8 or 9 (i,8 rare) [i,9].

Total vertebrae 33 (59), 34 (3).

COLOR IN ALCOHOL.—Overall coloration in specimens that retain guanine on scales silvery or silvery-golden, darker on dorsal portions of head and body. Specimens that lack guanine on scales tan to tannish-brown, darker dorsally. No pronounced pigmentation pattern on body and head. Middorsal region from rear of head to upper caudal peduncle with obscure dark band. Rayed and adipose dorsal fins, and caudal fin dusky. Small chromatophores outline fin rays, particularly elongate anteriormost dorsal-fin rays. Anteriormost rays of anal fin and dorsalmost rays of pectoral fin somewhat dusky.

DISTRIBUTION.—Middle and upper portions of Rio Amazonas drainage basin (Figure 32).

COMMON NAME.—In Peru: “yahuarachi” (Ortega and Vari, 1986:11).

LIFE HISTORY.—Goulding et al. (1988:132) report that this species is a detritivore. Bayley (1988:131) provides various data on growth rates and detritivory in the species.

DISTRIBUTION.—Rio Parnaiba drainage basin (Figure 34).

MATERIAL EXAMINED.—120 specimens (41,55.4–175.6mm SL).

BRAZIL. Piauí: Rio Puty (= Poti). MCZ 20305, 11 (4, 117.7–128.3, paralectotypes of Curimatus macrops); MCZ 20302, 1 (133.1, paralectotype of Curimatus macrops); MCZ 20301, 10 (4, 141.1–141.5, paralectotypes of Curimatus macrops); MCZ 20309, 1 (109.0, lectotype of Curimatus macrops); NMW 68905, 3 (100.3–123.9); NMW 68878, 3; NMW 68879, 4; NMW 68880, 4; NMW 68881, 4; NMW 68882, 3. San Gonçallo (= Saõ Gonçalo), USNM 120249, 3 (124.5–151.0, paralectotypes of Curimatus macrops); MCZ 20311, 5(113.5–175.6, paralectotypes of Curimatus macrops); Teresina, NMW 66901, 4 (115.7–119.3); USNM 258769, 4 (109.6–128.0); NMW 66891, 4; NMW 66899,4; NMW 66900, 4; NMW 66903, 4; NMW 68904, 4; NMW 68884, 1; NMW 68883,1; MZUSP 5095, 2. Rio Parnaiba near Buriti dos Lopes, MCZ 46801, 11 (3, 66.4–70.4); MCZ 46799, 6 (3, 64.3–73.4). Rio Parnaiba at Floriana, USNM 267317, 3. Maranhão: Rio Parnaiba basin, Engenho de Aqua, NMW 68826, 1 (106.9); NMW 68875, 5; NMW 68877, 5. Rio Parnaiba, USNM 267341, 5 (55.4–77.3).