Steindachnerina nigrotaenia ( Boulenger, 1902 )

Britski, Heraldo A., Melo, Bruno F., Vari, Richard P. & Oliveira, Claudio, 2019, Revalidation and redescription of Steindachnerina nigrotaenia and redescription of S. insculpta (Characiformes: Curimatidae), Neotropical Ichthyology 17 (1), pp. 1-14 : 5-9

Steindachnerina nigrotaenia ( Boulenger, 1902)

Fig. 2 , Tab. 2

Curimatus nigrotaenia Boulenger, 1902:2 [type-locality: Mato Grosso, rio Coxipó].- Eigenmann, 1910:421 [reference]. - Vari, 1989, tables 2, 3 [assignment to Steindachnerina ]. - Tortonese, 1961:184 [Catalog: three syntypes]. - Litz & Koerber, 2014:9 [Check list; synonym of Steindachnerina brevipinna ].

Curimata nigrotaenia .- Fernández-Yépez, 1948:73 [reference].- Fowler, 1950:288 [literature compilation].- Fowler, 1975:369 [reference].- Ringuelet, 1975:72 [ Argentina, rio Paraguai system].

Steindachnerina nigrotaenia .- Britski, 1996:74 (previous resurrection).- Britski et al., 1999:72 [diagnose in key; shortened description; text-figure; Pantanal do Mato Grosso].- Britski et al., 2007: 96 [diagnose in key; shortened description; text figure; Pantanal do Mato Grosso].- Polaz et al., 2014:125 [list of species from Parque Nacional do Pantanal Matogrossense].

Steindachnerina insculpta .- Vari, 1991:71 [in part, material from rio Paraguai basin, not from upper rio Paraná basin]. - Aguilera et al., 2018:1018 [ Argentina: río San Francisco, Bermejo river basin, Jujuy, and Madrejón El Divisadero, Bermejo river basin, Salta].

Steindachnerina brevipinna . - Vari, 1991:97 [in part, material from Mato Grosso, upper rio Paraguai].

? Curimata nasa .- Géry et al., 1987:425, fig. 41 [material from arroyo Trementina, rio Paraguai basin].

Diagnosis. Steindachnerina nigrotaenia can be distin- guished from all congeners, except S. binotata (Pearson, 1924) , S. biornata , S. dobula (Günther, 1868) , S. hypostoma (Boulenger, 1887) , S. insculpta , S. leucisca (Günther, 1868) , S. notograptos Lucinda & Vari, 2009 , and S. varii Géry, Planquette, Le Bail, 1991 , by possessing an unpigmented dorsal fin (vs. a dorsal fin with a spot of dark pigmentation on the basal portion of the middle rays). Steindachnerina nigrotaenia has 43 to 48 perforated scales in the lateral line series running from the supracleithrum to the middle rays of the caudal fin, differing from S. binotata , S. leucisca and S. notograptos , which have 50 or more perforated scales in that series and from S. biornata and S. varii which have fewer than 40 perforated scales in the lateral line series. Steindachnerina nigrotaenia differs from S. hypostoma by possessing a relatively shallower body with greatest body depth 24-27% of SL (vs. 29-34% of SL). Steindachnerina nigrotaenia differs from S. dobula and S. varii by having a dark midlateral stripe extending from the rear of the opercle posteriorly onto middle rays of caudal fin (vs. dark midlateral stripe beginning posterior to a verti- cal line through the dorsal-fin origin, and continuing posteriorly to the middle rays of the caudal fin). Steindachnerina nigrotaenia differs from the very similar S. insculpta by the generally higher number of perforated scales along the lateral line series (43 to 48, 45 most frequent, vs. 40 to 45, 42 most frequent and 44 and 45 in only 1.3% of specimens examined for this feature, respectively; Fig. 3 ), by the total number of scale rows in the transverse series from the dorsal-fin origin to the pelvic-fin base (13 to 16, 14 most frequent, vs. 12 to 14, 12 most frequent and 13.5 and 14 in only 6.4% and 1.3% of specimens examined for this feature, respectively; Fig. 4 ). Steindachnerina nigrotaenia can also be discriminated from 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, possession of 43 to 48 perforated scales in the lateral line series, 13 to 16 scales in the transversal series, lack of a dark spot on the basal portions of the dorsal fin and the presence of a dark midlateral stripe along the lateral surface of the body.

Description. Morphometric data of lectotype, paralecto- types and other specimens are summarized in Tab. 2 . Body relatively elongate, somewhat compressed. Dorsal profile of head slightly convex anteriorly, straight from the line 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 dorsal-fin base; 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 pelvic-fin origin, median series irregularly arranged anteriorly. Barely discernable median keel posterior to pelvic-fin origin.

Dorsal-fin margin rounded; anteriormost rays three to 3.5 times the length of ultimate ray. Pectoral-fin margin acute, extending one-half to two-third the distance to origin of pelvic fin in smaller adults, barely beyond that point in largest specimens examined. Pelvic-fin margin acute; pelvic fin extending about one half the distance to origin of anal fin. Caudal fin forked. Adipose fin well developed. Anal fin emarginate, anteriormost branched rays 2.5 to three times the length of ultimate ray.

Head profile pointed; upper jaw distinctly longer, mouth inferior; buccopharyngeal complex on roof of the 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.

Pored lateral-line scales from supracleithrum to medial caudal-fin rays 43(1), 44(9), 45*(22), 46(10), 47(1) or 48(1), 2 to 3 over caudal-fin base; series of scales from dorsal-fin origin to lateral line 6(8), 7*(31) or 8(5); series of scales from lateral line to pelvic-fin base 6*(39), 6.5(3) or 7(2); total series of scales from dorsal fin to base pelvic-fin base 13(4), 14*(36), 14.5(5), 15(3) or 16(1); series of scales from lateral line to first ray of anal fin 5*(6), 5.5(8) or 6(29); circumpeduncular scales 16*(36), 17(1), 18(3) or 20(3); predorsal scales 11*(13), 12(19) or 13(10); scales from dorsal fin to adipose fin 12*(7), 13(17), 14(16) or 15(3); scales from adipose fin to caudal fin 8(3), 9(10), 10(19), 11(8) or 12*(2); prepelvic scales 18(1), 19(8), 20*(10), 21(12), 22(5), 23(4) or 24(1); scales from pelvic fin to anus 8*(13), 9(21), 10(7) or 11(2); scales from anus to anterior margin of anal fin 2(4), 3(31) or 4*(9); scales from posterior margin of anal fin to anteroventral margin of caudal fin 8(1), 9(6), 10(16), 11*(16) or 12(2). All scales of lateral line pored with canals in scales straight.

Dorsal-fin rays ii,8,ii*; pectoral-fin rays i,12(3), i,13(7), i,14*(20), i,15(9) or i,16(4); pelvic-fin rays i,8*(41) or i,9(3); anal-fin rays ii-iii,5,ii(2) or ii-iii,6,ii*(42); caudal- -fin rays i,8,9,i*(38). Total vertebrae 28(8) or 29 (2).

Coloration in alcohol. Overall coloration of specimens re- taining 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 with stripe more prominent on the 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 nigrotaenia is distributed along the rio Paraguai basin ( Fig. 5 ).

Material examined. All from Brazil, rio Paraguai basin. BMNH 1902.2 .10.30, 43.5 mm SL, Mato Grosso , rio Coxipó, F. Silvestri. Lectotype of Curimatus nigrotaenia (designated herein). MSNG 14859 , 3 , 42.7 , 51.2 , 52.2 mm SL, same data as lectotype. Paralectotypes of Curimatus nigrotaenia (designated herein). MNRJ 11206 , 3 , 59.8 - 85.7 mm SL, Mato Grosso , Acorizal , rio Acorizal at bridge along road from Acorizal to Baús. MNRJ 11207 , 1 , 102.0 mm SL, Mato Grosso , Acorizal , ribeirão Baús. MNRJ 11214 , 1 , not measured, Mato Grosso , Acorizal , ribeirão Tangará , along road from Acorizal to Cuiabá. MZUSP 4383 , 3 ; MZUSP 4449 , 1 , 39.2 mm SL, Mato Grosso , Santo Antonio do Leverger , rio Cuiabá. MZUSP 21512 , 16 , Mato Grosso , Cuiabá, rio Coxipó da Ponte, 15°38’S 56°03’W. MZUSP 21656 , 6 , Mato Grosso , Santo Antonio do Leverger , rio Cuiabá. MZUSP 21662 , 2 , Mato Grosso, Barão do Melgaço, rio Cuiabá, Boca do Croará, 16°11’S 55°57’W. MZUSP 38015 , 2 , Mato Grosso , Cáceres , Porto Limão. MZUSP 38079 , 1 , Mato Grosso do Sul , Coxim , rio Taquari, Ilha da Goiaba, 18°30’00”S 54°45’00”W. MZUSP 40068 , 4 , Mato Grosso do Sul , Aquidauana , rio Aquidauana, Baia da Onça or Jatobá, Fazenda Alegrete, 20°28’00”S 55°48’00”W. MZUSP 45476 , 9 , Mato Grosso, rio Paraguai at Cáceres and vicinities. MZUSP 47762 , 130 , Mato Grosso, Barão de Melgaço , rio Cuiabá. MZUSP 54139 , 1 , rio Apa , small bay of the river. MZUSP 56234 , 1 , Mato Grosso, Chapada dos Guimarães, rio Casca. MZUSP 59541 , 41 , Mato Grosso do Sul, Corumbá, rio Vermelho, Fazenda Xaroes, 19°36’73”S 56°55’42”W. MZUSP 74361 , 4 , Mato Grosso , Santo Antonio do Leverger , rio Cuiabá , 3 km from the town. MZUSP 75480 , 2 , Mato Grosso , Cáceres, ribeirão das Flexas, along road from Cáceres to Cuiabá at about 69 km E of Cáceres. MZUSP 78750 , 3 , Mato Grosso , Porto Estrela , rio Saloba, along road at Estação Ecológica da Serra das Araras, 15°39’03”S 57°13’29”W. MZUSP 78845 , 1 , Mato Grosso , Diamantino, downstream of waterfall in the rio Paraguai, 14°28’32”S 56°23’32”W. MZUSP 78946 , 1 , Mato Grosso , Santo Antonio do Leverger , rio Cuiabá. MZUSP 87785 , 2 , Mato Grosso, Tangará da Serra, rio Sepotuba, salto Maciel, 15°55’59”S 57°39’00” W. MZUSP 89954 , 2 , Mato Grosso , rio Sepotuba. MZUSP 90075 , 8 , Mato Grosso, Curvelândia, lower rio Sepotuba, 15°53’34”S 57°38’44”W. MZUSP 90181 , 14 , Mato Grosso , lower rio Sepotuba. MZUSP 90422 , 27 , Mato Grosso, Curvelândia, rio Sepotuba, 15°46’07”S 57°38’54”W. MZUSP 90702 , 3 , Lambari d’Oeste , rio Sepotuba, at mouth of a creek, 15°10’00”S 57°41’00”W. MZUSP 91014 , 1 , Barra do Bugres , rio Sepotuba, 15°06’52”S 57°39’57”W. MZUSP 91060 , 2 , Cáceres , rio Sepotuba, artificial lagoon downstream of the bridge, 15°14’08”S 57°41’46”W. LBP 5636 , 1 (tissue 27395), Mato Grosso, Cuiabá, rio Coxipó , rio Paraguai . LBP 8573 , 1 (tissue 43355), Mato Grosso , Barra do Bugres, rio Paraguai . LBP 9818 , 6 (tissues 45230–45234, Mato Grosso do Sul , Miranda, rio Paraguai. LBP 9862 , 1 (tissue 45408), Mato Grosso do Sul, Miranda, rio Paraguai.

Figures

Fig. 2. a. Steindachnerina nigrotaenia, lectotype of Curimatus nigrotaenia, BMNH 1902.2.10.30, 43.5 mm SL, Brazil, Mato Grosso, rio Coxipó, upper rio Paraguai; b. LBP 1477, 43.4 mm SL, Brazil, Mato Grosso do Sul, Coxim, rio Taquari, upper rio Paraguai.

Fig. 3. Histogram of number of lateral-line scales against number of specimens of Steindachnerina brevipinna, S. insculpta and S. nigrotaenia.

Fig. 4. Histogram of number of series of scales from dorsal-fin origin to pelvic-fin base against number of specimens of Steindachnerina brevipinna, S. insculpta and S. nigrotaenia.

Fig. 5. Distribution map of Steindachnerina brevipinna in both rio Paraná and rio Paraguai (green), S. nigrotaenia in the rio Paraguai (red), and S. insculpta in the upper rio Paraná (yellow). Pentagons indicate type localities. Some symbols represent more than one collecting locality.

Tables

Tab. 2. Morphometric data for Steindachnerina nigrotaenia and S. insculpta. N = number of specimens. SD = Standard deviation. Range of each species includes the lectotype of S. nigrotaenia (BMNH 1902.2.10.30) and the paratype of S. insculpta (MZUSP 1376), respectively.

		Steindachnerina nigrotaenia					Steindachnerina insculpta
	Lectotype	N	Range	Mean	SD	Paratype	N	Range	Mean	SD
Standard length (mm)	43.5	44	37.0-90.3	63.4	-	105.0	78	42.6-108.1	75.6	-
Percentages of standard length
Body depth	26.5	44	25.0-33.8	28.8	1.5	29.5	78	25.6-34.1	30.1	1.7
Caudal peduncle depth	11.0	44	10.3-11.7	11.0	0.3	11.7	78	10.8-12.4	11.7	0.4
Head length	32.0	44	25.7-32.5	29.0	1.7	18.9	78	25.6-30.2	28.1	0.8
Predorsal distance	47.2	44	44.3-49.7	46.8	1.2	46.8	78	43.3-49.7	46.2	1.2
Prepelvic distance	51.9	44	48.8-55.4	52.4	1.4	54.9	78	48.8-58.0	52.1	1.6
Pectoral-fin length	15.2	44	15.0-20.0	18.1	0.9	17.9	78	15.6-19.8	18.0	0.9
Pelvic-fin length	19.9	44	18.0-22.3	19.7	0.9	19.6	78	15.5-21.8	19.0	1.2
Percentages of head length
Eye diameter	32.4	44	27.6-34.9	30.5	1.8	27.7	78	26.3-33.5	29.8	1.7
Snout length	34.5	44	30.1-35-6	32.9	1.3	35.1	78	29.7-38.9	34.1	1.7
Interorbital distance	33.1	44	31.7-43.2	38.0	2.2	39.7	78	38.3-44.8	41.0	1.8