Steindachnerina insculpta

Steindachnerina insculpta (Fernández-Yépez, 1948)

Fig. 6, Tab. 2

Cutimata elegans Amaral Campos, 1945:46 [Brazil: rio Mogi Guaçu].- Britski, 1972:83 [Brazil, São Paulo, rio Paraná basin]. - Foresti et al., 1974:249 [karyotypes].- Nomura, 1977:727 [Brazil: rio Mogi-Guaçu; meristic].- Nomura, Taveira, 1979:331 [life history].

Cruxentina insculpta Fernández-Yépez, 1948:53, figs. 27, 28 [type-locality: Brazil: São Paulo, rio Tatuhy (= Tatuí); autorship cited as Amaral Campos].- Britski, 1969:200, 203 [correction of originally cited authorship, depositary and collector; meristic and morphometrics].- Fowler, 1975:368 [reference].- Vari, 1989, tables 2, 3 [assignment to Steindachnerina].

Curimata elegans.- Gomes, 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 Gerais, Três Marias; chromosome counts].

Pseudocurimata elegans elegans.- Godoy, 1975: 88, 103, 129, fig. 132A, 133 [Brazil: São Paulo, rio Mogi-Guassu; life history data; meristic and morphometrics; not cited occurrence in drainage basins other than upper rio Paraná].

Steindachnerina insculpta.- Venere, Galetti Júnior, 1989:18, 19, fig. 19 [upper rio Paraná basin, rio Mogi-Guaçu and rio Passa- Cinco; karyotype information].- Vari, 1991:71 [in part Brazil, material from upper rio Paraná basin above Sete Quedas; not from rio Paraguai system and from Goiás]. - Koerber et al., 2017:16 [reference; type locality mistakenly referred to as being in Venezuela].

? Curimata nasa.- Géry et al., 1987:425, fig. 41 [material from arroyo Porooco and Itaipu Lake, rio Paraná basin].

Diagnosis. Steindachnerina insculpta can be distinguished from congeners, except S. binotata, S. biornata, S. dobula, S. hypostoma, S leucisca, S. nigrotaenia, S. notograptos, and S. varii by possessing a plain dorsal fin (vs. dorsal fin with a spot of dark pigmentation on the basal portion of the middle rays). Steindachnerina insculpta has 40 to 45 scales in the lateral line series, differing from S. binotata, S. leucisca, S. hypostoma, S. notograptos, and S. gracilis which have 46 or more scales and from S. biornata which has 31 to 34 scales in the lateral line series. Steindachnerina insculpta differs from S. dobula and S. varii by having a dark midlateral stripe extending from rear of opercle posteriorly onto middle rays of caudal fin (vs. dark midlateral stripe beginning posterior to vertical line from dorsal-fin origin). Steindachnerina insculpta differs from the very similar S. nigrotaenia by the lower modal number of perforated scales in the lateral line series (40 to 45, 42 most frequent vs. 43 to 48, 45 most frequent and 43 in only 2.27% of specimens examined for this feature; Fig. 3), and by the total number of scale rows in the transverse series from the dorsal-fin origin to the pelvicfin base (12 to 14, 12.5 most frequent, 13.5 and 14 less frequent vs. 13 to 16, 14 most frequent; 13 in only 8.16% of specimens examined for this feature; Fig. 4). Steindachnerina insculpta can also be discriminated from its congeners by a combination of the following features: multiple lobulated fleshy processes on the roof of the oral cavity, absence of a wide, flattened prepelvic region of the body, 40 to 45 scales on the lateral line, 12 to 14 scales on the transversal series, lack of a dark spot on basal portions of the dorsal fin and the presence of a dark midlateral stripe along the body.

Description. Morphometric data of Steindachnerina insculpta are summarized in Tab. 2. 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 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 dorsal 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 pelvicfin origin, median series less regularly arranged anteriorly. Median keel barely discernable posterior to pelvic-fin origin.

Dorsal-fin margin rounded; anteriormost rays three to three and half times length of ultimate ray. Pectoral-fin margin acute, extending one-half to two-third distance to origin of pelvic fin in smaller adults, barely beyond that point in the largest examined specimens. Pelvic-fin margin acute; pelvic fin extending 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 the length of ultimate ray.

Head pointed in profile; upper jaw distinctly longer, mouth inferior; buccopharyngeal complex on roof of oral cavity in adults consisting of multiple lobulated fleshy bodies; nostrils very close, anterior circular, posterior crescent-shaped with aperture closed by thin flap of skin separating nares; adipose eyelid present, more developed anteriorly, with broad, vertically ovoid opening over center of eye.

Total pored lateral-line scales 40 (3), 41(13), 42(31), 43(28), 44(1) or 45(1); two to three scales over caudal fin. Longitudinal series of scales from dorsal-fin origin to lateral line 6(51), 6.5(23) or 7(4); longitudinal series of scales from lateral line to base of pelvic fin 5(26), 5.5(49) or 6(3); total lateral series from dorsal-fin origin to pelvic-fin base 12(23), 12.5(29), 13(20), 13.5(5) or 14(1); longitudinal series of scales from lateral line to first ray of anal fin 4.5(9) or 5(69); circumpeduncular scales 16(77) or 17(1); predorsal scales 10(7), 11(38), 12(17) or 13(5); scales from end of dorsal fin to adipose fin 12(6), 13(34) or 14(37); scales from end of adipose fin to anteriormost dorsal caudal-fin ray 8(3), 9(14), 10(35), 11(16) or 12(4); prepelvic scales 19(3), 20(11), 21(26), 22(11), 23(15) or 24(4); scales from pelvic fin to anus 7(5), 8(23), 9(38), 10(10) or 11(1); scales from anus to anal-fin origin 2(8), 3(51) or 4(2); scales from end of anal fin to anteriormost ventral caudal-fin ray 9(13), 10(37), 11(19) or 12(4); all scales of lateral line pored, canals in scales of lateral line straight.

Dorsal-fin rays ii-iii,8,ii(76); pectoral-fin rays i,12(2), i,13(17), i,14(40), i,15(18) or i,16(1); pelvic-fin rays i,7(1), i,8(76) or i,9(1); anal-fin rays ii-iii,6,ii(76) or iii5,ii(1); caudal-fin rays i,8,9,i(78). Total vertebrae 28(8) or 29(3).

Coloration 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, 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; not as well developed in juveniles, consisting of discrete spots surrounding pores of lateral line. 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 spot on middle rays. Other fins hyaline.

Sexual dimorphism. Secondary sexual characters were not found.

Geographical distribution. Steindachnerina insculpta is restricted to the upper rio Paraná basin (Fig. 5).

Material examined. All from Brazil, upper rio Paraná. CAS 20312, holotype of Cruxentina insculpta, 95.3 mm SL, São Paulo, rio Tatuhy (= Tatuí, SP). MZUSP 1376, 1, paratype of Cruxentina insculpta, 105.6 mm SL, rio Tatuhy (= Tatuí). USNM 295275, 5, 76.3 –104.0 mm SL; MZUSP 20381, 98, Alfredo de Castilho, córrego do Moinho. USNM 295272, 5 (4, 66.7-78.4 mm SL); MZUSP 21515, 26, Miguelópolis, Volta Grande reservoir. USNM 295271, 22 (5, 51.8-87.8); MNRJ 5669, 5 (3, 74.4-81.7); MZUSP 20700, 15; MZUSP 20704, 33; MZUSP 20739, 19; MZUSP 20741, 1; MZUSP 20744, 2; MZUSP 20750, 74 (10, 80.9-90.4); MZUSP 20791, 1; BMNH 1946.12.23:97-111, 11, 69.9-79.5 mm SL, rio Mogi-Guaçu, Emas. MZUSP 20672, 36; MZUSP 20691, 17, rio Mogi-Guaçu, Cachoeira de Emas. USNM 295274, 9; MZUSP 20711, 10, rio Mogi-Guaçu, Pirassununga. CAS 41729, 4 66.0- 91.9 mm SL; NWW 67002, 3; NMW 68914, 2, Piracicaba, rio Piracicaba. MZUSP 20755, 64; MZUSP 20758, 37; MZUSP 20768, 1, Corumbataí, rio Corumbataí. MZUSP 21317, 10, 88.7 - 101.4 mm SL; USNM 295266, 2, Borborema, rio Tietê. MZUSP 21525, 1, Marimbondo, rio Grande. MZUSP 21429, 106, Ilha Solteira, rio Paraná. MZUSP 21603, 2, Pedreira, rio Jaguari. MZUSP 20865, 1, rio Pardo, usina de Limoeiro. MZUSP 21471, 1, Botucatu. Minas Gerais: MZUSP 21505, 2, Alfenas, rio Grande, Furnas reservoir. MZUSP 21502, 1, Boa Esperança, rio Grande. Mato Grosso do Sul: MZUSP 20683,15; MZUSP 20714, 84; MZUSP 20853, 18, Três Lagoas, usina de Jupiá, rio Paraná. MZUSP 20824, 1; MZUSP 20894, 1, Três Lagoas, rio Sucuriú. Paraná: MZUSP 21620, 103, rio Paraná, Guaíra, above Sete Quedas. LBP 3192, 4 (tissues 19389– 19390), São Paulo, Conchas, rio Tietê; LBP 5207, 8 (tissue 26343), Paraná, Porto Rico, rio Paraná; LBP 6671, 1 (tissue 32081); LBP 19770, 1 (tissue 32158), Paraná, Marilena, rio Paraná; NUP 1424, 4; NUP 4576, 6, Guaíra, rio Paraná, Itaipu reservoir. NUP 1753, 7, Santa Helena, rio Paraná, Itaipu reservoir. NUP 7513, 4, Foz do Iguaçu, rio Paraná, Reservatório Itaipu.