Steindachnerina insculpta (Fernández-Yépez 1948)

Steindachnerina insculpta (Fernández-Yépez, 1948)

Curimatus elegans.—Campos, 1945:46 [Brazil: Rio Mogi-Guaçu].—Britski, 1972:83 [Brazil: São Paulo, Rio Paraná basin].—Foresri et al. 1974:249 [karyotypes].—Nomura, 1977:727 [Brazil: Rio Mogi-Guaçu; meristics].— Nomura and Taveira, 1979:331 [life history].

Cruxentina insculpta Fernández-Yépez, 1948:53, figs. 27, 28 [type-locality: Brazil: São Paulo, Rio Tatuhy (= Tatui); authorship cited as Amaral Campos].—Britski, 1969:200,203 [correction of originally cited authorship, depository and collector; meristics and morphometrics].—Fowler, 1975:368 [reference].—Van, 1989a, tables 2, 3 [assignment to Steindachnerina].

Curimata elegans.—Gomes and Monteiro, 1955:88, 103, 129 [São Paulo, Pirassununga, occurrence in flowing and still waters].—Oliveira et al., 1988:594 [in part, Brazil: São Paulo, Rio Mogi-Guaçu and Botucatu; not Minas Gérais, Três Marias; chromosome counts].

Pseudocurimata elegans elegant.—de Godoy, 1975:585, fig. 132A, 133 [Brazil: São Paulo, Rio Mogi Guassu (= Guaçu); life history data; meristics and morphometrics; not cited occurrence in drainage basins other than upper Rio Paraná].

Curimata nasa.—Géry et al., 1987:425, fig. 41 [Paraguay: Río Paraguay and Río Paraná].

Steindachnerina insculpta.—Venere and Galetti, 1989:18, 19, fig. 19 [Brazil: upper Rio Paraná basin, Rio Mogi-Guaçu and Rio Passa-Cinco; karyotype information].

DIAGNOSIS.—The multiple lobulate fleshy processes on the roof of the oral cavity, absence of a wide, flattened prepelvic region of the body, lack of a dark spot on the basal portions of the dorsal fin, possession of 36 to 46 lateral-line scales to the hypural joint, and the presence of a dark midlateral stripe along the length of the body discriminate Steindachnerina insculpta from its congeners.

DESCRIPTION.—Body relatively elongate, somewhat compressed. Dorsal profile of head very slightly convex anteriorly, straight from above orbit to rear of head. Dorsal profile of body straight or very slightly convex from rear of head to origin of dorsal fin; straight and posteroventrally slanted at base of dorsal fin, straight from base of last dorsal-fin ray to caudal peduncle. Dorsal surface of body transversely rounded anteriorly, with indistinct median keel immediately anterior to dorsal fin, smoothly rounded transversely posterior to fin. Ventral profile of body gently curved from tip of lower jaw to caudal peduncle. Prepelvic region obtusely flattened, with median series of scales proximate to pelvic-fin origin, median series less regularly arranged anteriorly. Barely discernable median keel posterior to pelvic-fin origin.

Greatest depth of body 0.29–0.34 [0.33]; snout tip to origin of dorsal fin 0.45–0.50 [0.48]; snout tip to origin of anal fin 0.80–0.85 [0.83]; snout tip to origin of pelvic fin 0.52–0.55 [0.55]; snout tip to anus 0.73–0.78 [0.76]; origin of dorsal fin to hypural joint 0.55–0.59 [0.58]. Dorsal-fin margin rounded; anteriormost rays three to three and one-half times length of ultimate ray. Pectoral-fin margin acute; length of pectoral fin 0.17–0.21 [0.20], extends one-half to two-thirds distance to origin of pelvic fin in smaller adults, barely beyond that point in largest specimens examined. Pelvic-fin margin acute; length of pelvic fin 0.18–0.22 [0.19], reaches about one-half distance to origin of anal fin. Caudal fin forked. Adipose fin well developed. Anal fin emarginate, anteriormost branched rays two and one-half to three times length of ultimate ray. Caudal peduncle depth 0.11–0.13 [0.12].

Head pointed in profile, head length 0.27–0.31 [0.28]; upper jaw distinctly longer, mouth inferior, portion of buccopharyngeal complex on roof of oral cavity in adults consisting of multiple lobulate fleshy bodies; snout length 0.29–0.33 [0.32]; nostrils very close, anterior circular, posterior crescent-shaped, with aperture closed by thin flap of skin separating nares; orbital diameter 0.25–0.29 [0.28]; adipose eyelid present, more developed anteriorly, with broad, vertically ovoid opening over center of eye; length of postorbital portion of head 0.42–0.47 [0.46]; gape width 0.25–0.30 [0.26]; interorbital width 0.38–0.42 [0.41].

Pored lateral-line scales to hypural joint 37 to 42 [38]; all scales of lateral line pored, canals in scales of lateral line straight; 3 to 5 series of scales extend beyond hypural joint onto caudal-fin base; 6½ to 7½ [6½] scales in transverse series from origin of dorsal fin to lateral line; 4½ to 5½ [5] scales in transverse series from lateral line to origin of anal fin.

Dorsal-fin rays ii,9 [ii,9]; anal-fin rays ii,7 or iii,7 (when three unbranched rays present, first very short) [ii,7]; pectoral-fin rays 12 to 15 [14]; pelvic-fin rays i,8 [i,8].

Total vertebrae 33 (28), 36 (1, see “Remarks” below).

COLOR IN ALCOHOL.—Overall coloration of specimens retaining guanine on scales silvery to silvery golden, darker on dorsal portions of head and body. Ground coloration of specimens lacking guanine on scales tan to yellow, darker dorsally. Head dusky dorsally, with irregular patch of dark pigmentation extending from rear of orbit across opercle; degree of intensity of dark pigmentation and extent of patch variable among individuals. Irregular, dark, longitudinal stripe extending along lateral line from supracleithrum to base of middle caudal-fin rays. Stripe slightly wider posteriorly, continuous posteriorly with dusky stripe on middle caudal-fin rays. Stripe in adults continuous, about one scale wide (Figures 47, 48); not as well developed in juveniles, consisting of discrete spots surrounding pores of lateral line (Figure 49). Caudal-fin stripe more prominent on anterior portion of rays. Anterior margin and distal portions of dorsal fin typically dusky in adults. Ventral lobe and dorsal rays of dorsal lobe of caudal fin dusky. All caudal-fin rays outlined by small chromatophores on membranes. Adipose fin dusky distally. Dorsal fin with dusky anterior region in many specimens, without any discrete dark spot on middle rays. Other fins hyaline.

DISTRIBUTION.—Upper Rio Paraná basin above Sete Quedas and Rio Paraguay system (Figure 41; see also “Remarks” with respect to records from Río Paraguay system).

KARYOTYPE.—Foresti et al. (1974:249; as Curimatus elegans) followed by Oliveira, et al. (1988:594; as Curimata elegans) report that this species has 2n = 54 chromosomes, with a fundamental number of 108. No evidence of chromosomal heteromorphism was found. Venere and Galetti (1989:19) confirm the karyotype count and discuss it within a broader phylogenetic framework.

ECOLOGY AND LIFE HISTORY.—Gomes and Monteiro (1955) note that this species is common at Pirassununga along the Rio Mogi-Guaçu, and occurs in large numbers in both still and slow running waters, de Godoy (1975:590) cites this species as a member of the “piracema,” the mass fish migration through the rapids at the Cachoeira de Ernas in the Rio Mogi Guassu. The species is found in the area throughout the year, but is most common during the period from September to February. Both sexes begin ripening in September and spawning takes place between the end of November and the middle of January. According to de Godoy (1975:591) the species eats Zooplankton for the first 30 to 50 days after hatching. At the end of that period the larval dentition is lost, the intestinal system lengthens, and the species switches to a diet of algae and organic detritus. Nomura and Taviera (1979) found at least 23 different genera of algae in the stomachs of adults of the species. Those authors also provide additional life history data for the species.

MATERIAL EXAMINED.—886 specimens (64, 39.2–105.6).

BRAZIL. Rio Paraná, no specific locality, BMNH 1902.2.10:31, 1. Goiás: Goiána, USNM 268046, 1 (79.5). Rio Corumbá, MNRJ 11210, 1 (94.8). Distrito Federal: Córrego Pipiripau, near Planaltina, MZUSP 21530, 4. Lagoa Paranoá, Brasilia, MZUSP 21719, 1. Ribierão Santana, at road crossing 30 km S of Barragem de Paranoá (Rio São Bartolomeu system, 15°55′S, 47°46′W), USNM 295273, 11 (1, 83.0). São Paulo: Rio Tatuhy (= Tatuí), CAS 20312, 1 (95.3, holotype of Cruxentina insculpta; see also “Remarks” under this species); MZUSP 1376, 1 (105.6, paratype of Cruxentina insculpta). Município de Alfredo de Castilho, Córrego do Moinho, USNM 295275, 5 (76.3–104.0); MZUSP 20381, 98. Represa de Volta Grande, Miguelópolis, USNM 295272, 5 (4, 66.7–78.4); MZUSP 21515, 26. Rio Mogi–Guaçu, Ernas, USNM 295271, 22 (5, 51.8–87.8); MNRJ 5669, 5 (3, 74.4–81.7); MZUSP 20750, 74 (10, 80.9–90.4); BMNH 1946.12.23:97–111, 11 (67.9–79.5); MZUSP 20741, 1; MZUSP 20791, 1; MZUSP 20700, 15; MZUSP 20744, 2; MZUSP 20704, 33; MZUSP 20739, 19. Rio Mogi-Guaçu, Cachoeira de Ernas, MZUSP 20672, 36; MZUSP 20691, 17. Rio Mogi-Guaçu, Pirassununga (= Piraçununga), USNM 295274, 9; MZUSP 20711, 10. Piracicaba, CAS 41729, 4 (66.0–91.9); NMW 67002, 3; NMW 68914, 2. Rio Corumbataí, Corumbataí, MZUSP 20768, 1; MZUSP 20755, 64; MZUSP 20758, 37. Borborema, Rio Tietê, MZUSP 21317, 10 (88.7–101.4); USNM 295266, 2. Rio Grande, Marimbondo, MZUSP 21525, 1. Rio Jaguarí, Pedreira, MZUSP 21603, 2. Rio Pardo, Usina de Limoeiro, MZUSP 20865, 1. Botucatu, MZUSP 21471, 1. Minas Géraisí: Rio Grande, Represa de Furnas, Munícipio de Alfenas, MZUSP 21505, 2. Rio Grande, Boa Esperança, MZUSP 21502, 1. Rio Miranda, Salobra, MNRJ 8900, 4 (2, 89.0–90.1). Represa de Jaguara, USNM 295267, 2. Mato Grosso: Rio Paraná, Jupiá, MZUSP 20853, 18; MZUSP 20683, 15; MZUSP 20714, 84. Rio Sucuriú, Três Lagoas, MZUSP 20824, 1; MZUSP 20894, 1. Ilha Solteira, MZUSP 21429, 106. Rio Cuiabá, Santo Antônio do Leverger, MZUSP 4383, 3; MZUSP 4449, 1 (39.2). Rio Acorizal, at bridge along road from Acorizal to Baús, MNRJ 11206, 3 (59.8–85.7). Ribeirão Baús. Munícipio Acorizal, MNRJ 11207, 1 (102.0). Ribeiráo Taguará, along road from Acorizal to Cuiabá, MNRJ 11214, 1. Munícipio de Baráo de Melgaço, MZUSP 21662, 2. Paraná: Rio Paraná, Guáira, above Sete Quedas, MZUSP 21620, 103.