Curimata inornata Vari 1989

Feeds on detritus (Ref. 12371).

fisheries: minor commercial

Curimata inornata

Curimata A.—Vari, 1984b:34–35 (Amazon River basin); 1988, fig 10 [phylogenetic biogeography]; 1989, tables 2, 3 [phylogenetic relationships].

DIAGNOSIS.—The possession of 31 vertebrae, a body depth 0.34–0.38 of SL, 7 to 9 branched anal rays, and the absence of any marked body pigmentation patterns distinguish Curimata inornata from all other members of the genus with the exception of C. incompta. The interorbital distance in C. inornata is less than the distance from the tip of the snout to the anterior margin of the opening in the adipose eyelid. In C. incompata the interorbital distance is greater than that from the snout to the eyelid margin. The species also differ in the relative length of the postorbital portion of the head (0.32–0.37 of HL in C. inornata vs. 0.39–0.46 in C. incompta, Figure 22) orbital diameter (0.32–0.39 of HL vs. 0.29–0.33), and snout length (0.31–0.36 of HL vs. 0.28–0.32). A large series of internal characters also distinguish the species (see “Synapomorphy List and Phylogenetic Reconstruction”).

DESCRIPTION.—Body moderately elongate, somewhat compressed. Dorsal profile of head straight or very slightly convex. Dorsal profile of body slightly convex from rear of head to origin of rayed dorsal fin; straight and posteroventrally slanted at base of dorsal fin, gently convex from base of last dorsal-fin ray to caudal peduncle. Dorsal surface of body with an indistinct median keel anterior to rayed dorsal fin, smoothly rounded transversely posterior to fin. Ventral profile of body gently curved from tip of lower jaw to caudal peduncle, convexity more pronounced posterior to pelvic fin origin. Prepelvic region flattened, margined laterally by distinct, nearly right, angles in body wall. Prepelvic region with a median series of enlarged scales flanked on each side by a 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 wall about two scales dorsal of ventral midline on each side of postpelvic portion of body.

Greatest body depth at origin of rayed dorsal fin, depth 0.34–0.40 [0.38]; snout tip to origin of rayed dorsal fin 0.49–0.54 [0.50]; snout tip to origin of anal fin 0.80–0.87 [0.80]; snout tip to origin of pelvic fin 0.52–0.59 [0.53]; snout tip to anus 0.76–0.84 [0.77]; origin of rayed dorsal fin to hypural joint 0.53–0.59 [0.58]. Rayed dorsal fin pointed, anteriormost rays somewhat lengthened in some individuals, 3.0–4.5 times length of ultimate ray. Pectoral fin pointed; length of pectoral fin 0.18–0.24 [0.20], extends three-quarters distance to vertical through origin of pelvic fin. Pelvic fin pointed, length of pelvic fin 0.18–0.24 [0.20], reaches one-half to three-quarters distance to origin of anal fin. Caudal fin forked. Adipose fin well developed. Anal fin emarginate, anteriormost branched rays approximately three times length of ultimate ray. Caudal peduncle depth 0.10–0.12 [0.11].

Head distinctly pointed, head length 0.30–0.33 [0.31]; upper jaw very much longer, mouth distinctly inferior, snout length 0.31–0.37 [0.35]; nostrils of each side of head very close, anterior circular, posterior crescent shaped with aperture closed by thin flap of skin separating nares; eye large, orbital diameter 0.32–0.39 [0.33]; adipose eyelid well-developed, particularly anteriorly, with vertically ovoid opening over center of eye; length of postorbital portion of head 0.32–0.37 [0.35]; gape width 0.24–0.30 [0.27]; interorbital width 0.39–0.44 [0.42].

Pored lateral-line scales from supracleithrum to hypural joint 47 to 56 [55]; all scales of lateral-line pored, canals in scales straight or slightly divergent; 4 to 7 series of scales extend beyond hypural joint onto caudal fin base; 12 to 15 [13] scales in a transverse series from origin of rayed dorsal fin to lateral line; 7 to 9 [8] scales in a transverse series from the lateral line to origin of anal fin. Median series of enlarged prepelvic scales 14 to 16.

Dorsal-fin rays ii,8–9 or iii,8–9 [ii,9]; anal-fin rays ii,7–9 or iii,7–8 [ii,8]; pectoral-fin rays 13 to 16 [15]; pelvic-fin rays i,8–9 [i,9].

Total vertebrae 31 (56), 32(3).

COLOR IN ALCOHOL.—Specimens that retain guanine on scales silvery, darker on dorsal portions of head and body. Specimens that lack guanine on scales tannish-brown to brown, darker dorsally. Distinct dark middorsal band extends from posterior of insertion of last dorsal-fin ray to insertion of dorsalmost caudal-fin ray. Rayed and adipose dorsal fins and caudal fins dusky. Rays of those fins outlined by a series of small chromatophores. Other fins hyaline or only slightly dusky.

DISTRIBUTION.—Middle and lower portions of the Rio Amazonas basin (Figure 23).

ETYMOLOGY.—The specific epithet is inornata from the Latin for unadorned, in reference to the plain body, head, and fin pigmentation of the species.

MATERIAL EXAMINED.—341 specimens (73,92.1–132.3).

HOLOTYPE.—BRAZIL. Pará: Rio Tapajós, Itaituba, edge of river channel (approx. 4°17′S, 55°59′W), MZUSP 28648, 127.0 mm SL, collected by M. Goulding, Sep–Oct 1983.

PARATYPES.—BRAZIL. Pará: Same locality as holotype: 23 specimens: MZUSP 28649, 5 (117.3–136.5); AMNH 55629, 2 (126.3–129.3); BMNH 1984.11.8:7–8, 2 (122.8–129.0); ANSP 153667, 2 (124.5–128.1); MCZ 61406, 2 (124.0–127.7); CAS 55892, 2 (121.7–127.5); USNM 267994, 8 (118.3–135.3). Rio Xingu, Belo Monte, edge of river channel (approx. 3°05′S, 51°46′W), MZUSP 28650, 5 (126.1–135.6); USNM 267993, 10 (104.6–138.2), collected by M. Goulding, Jul–Aug 1983. São Luís, Rio Tapajos (approx. 4°25′S, 50°15′W), collected by the Expediçao Permanente da Amazonas under the direction of P. Vanzolini, 4–8 Sep 1970; 19 specimens: MZUSP 21392, 9 (113.0–138.1), USNM 268597, 5 (115.7–131.7); AMNH 55630, 1 (111.8); BMNH 1984.11.8:6, 1 (119.8); CAS 55893, 1 (114.0); ANSP 153668, 1 (116.2). Oriximiná, Lago Paru (approx. 1°45′S, 55°52′W), MZUSP 5592, 1 (117.9) collected by Expediçao Permanente de Amazonas, 1967. Mato Grosso. Rio Arinos, Pôrto dos Gauchos (approx. 11°29′S, 57°22′W), USNM 267966, 1 (133.8), collected by M. Goulding, 19 Aug 1984.

The following specimens were examined, but are not part of the type series. BRAZIL. Pará: Rio Tapajos, Alter de Chão, MZUSP 9528, 1 (119.1). Rio Tapajós, Maloquina near Itaituba, MZUSP 21410, 3 (117.7–124.0); MZUSP 21900, 1 (131.8). Rio Tapajós near Porto Flexal, MZUSP 24478, 1 (132.3). Rio Tapajós, Itaituba, MZUSP 29534, 220 (taken with holotype). Rio Trombetas, Reserva Biológica de Trombetas, MZUSP 15857, 5 (92.1–118.5). Rio Trombetas, Oriximiná, MZUSP 5419, 1 (102.6); MZUSP 5420, 1 (110.9). Rio Xingu, Belo Monte, MZUSP 32263,43. Rio Itacaiunas, Caldeirao, MZUSP 29535, 4. Amazonas: Rio Solimões, Coari, MZUSP 20920, 1 (121.8).