Astyanax gymnogenys Eigenmann, 1911

Oliveira, Carlos Alexandre Miranda, Bertaco, Vinícius Araújo, Graça, Weferson Júnio Da & Pavanelli, Carla Simone, 2019, Redescription of Astyanax gymnogenys Eigenmann, 1911 (Characiformes Characidae), a senior synonym of Astyanax longirhinus Garavello & Sampaio 2010, Zootaxa 4668 (2), pp. 229-244 : 231-234

Astyanax gymnogenys Eigenmann, 1911

( Figs. 1–2 ; Tables 1–2 )

Astyanax gymnogenys Eigenmann, 1911: 179 , plate IX (original description, type-locality: rio Iguassú, Porto União).—Fowler, 1948: 51 (listed).— Severi & Cordeiro, 1994: 17–18 (listed, original description translated to Portuguese).— Garavello et al., 1997: 71 (brief description, diagnosis).—Lima et al., 2003: 110 (listed).— Garavello & Sampaio, 2010: 852, 853, 862 (redescription).— Baumgartner et al., 2012: 74, 79 (in part; listed, brief description and diagnosis; photo actually belong to A. gymnodontus ).— Ingenito & Duboc, 2014: 282 (inclusion in Astyanax scabripinnis species complex).

Astyanax sp. A.— Severi & Cordeiro, 1994: 19 (brief description; drawing; middle rio Iguaçu).

Astyanax sp. G.— Garavello et al., 1997: 73 (brief description, diagnosis).

Astyanax gymnogenis [sic]— non Eigenmann, 1911.— Garavello & Sampaio, 2010: 847–854, 860–864, fig. 1–3, 9 (redescription).

Astyanax longirhinus Garavello & Sampaio, 2010: 853–854 , fig. 4 (original description, type-locality: rio Iguaçu downstream from the Salto Santiago dam, between Laranjeiras do Sul and Chopinzinho, Laranjeiras do Sul, Paraná, Brazil).— Baumgartner et al., 2012: 74, 81 (listed, brief description, diagnosis). [Syn. nov.].

Astyanax longirhynus [sic] Garavello & Sampaio, 2010: 849 (title of the Table 1 ).

Diagnosis. Astyanax gymnogenys differs from all congeners inhabiting the río de La Plata drainage and adjoining drainages (rio Ribeira de Iguape and coastal rivers in Paraná and Santa Catarina states) as follows. It differs from A. biotae Castro & Vari , A. bockmanni Vari & Castro , A. dissimilis Garavello & Sampaio , A. eigenmanniorum , A. endy Mirande, Aguilera & Azpelicueta , A. hermosus Miquelarena, Protogino & Lopes , A. lineatus , A. marionae , A. pirapuan Tagliacollo, Britzke, Silva & Benine , A. pynandi Casciotta, Almirón, Bechara, Roux & Diaz , A. ribeirae , and A. tumbayaensis Miquelarena & Menni by having 39–43 lateral line scales (vs. 38 or less lateral-line scales). It differs from A. aramburui Protogino, Miquelarena & López , A. bifasciatus Garavello & Sampaio , A. dissensus Lucena, Castro & Bertaco , A. henseli Melo & Buckup , A. ita Almirón, Azpelicueta & Casciotta , A. jordanensis Alcaraz, Pavanelli & Bertaco , A. leonidas Azpelicueta, Casciotta & Almirón , A. minor Garavello & Sampaio , A. paranae , A. totae Haluch & Abilhoa , and A. xiru Lucena, Castro & Bertaco by having the margin of the third infraorbital distant from the margin of preopercle, leaving a broad naked area between these bones, more than 25% of the depth of third infraorbital (vs. margin of third infraorbital close to the margin of preopercle, leaving a narrow naked area, less than 25% of the depth of third infraorbital). It differs from A. correntinus , A. erythropterus , A. latens Mirande, Aguilera & Azpelicueta , A. pelegrini , A. saguazu Casciotta, Almirón & Azpelicueta , A. schubarti Britski , A. stenohalinus , A. trierythropterus Godoy , and A. tupi Azpelicueta, Mirande, Almirón & Casciotta , by having 17–22 branched rays in the anal fin (vs. 23 or more branched anal-fin rays). Astyanax gymnogenys differs from A. brachypterygium Bertaco & Malabarba , A. chico Casciotta & Almirón , A. ojiara Azpelicueta & Garcia , A. paris Azpelicueta, Almirón & Casciotta , A. taurorum Lucena, Zaluski & Lucena and A. troya Azpelicueta, Casciotta & Almirón by having a single humeral blotch (vs. two humeral blotches). It differs from A. abramis , A. janeiroensis , A. lacustris , A. laticeps and A. serratus Garavello & Sampaio by having a vertically-elongated humeral blotch (vs. horizontally-elongated oval humeral blotch). Astyanax gymnogenys differs from A. eremus Ingenito & Duboc , and A. varzeae Abilhoa & Duboc by having a concave profile very well marked at supraoccipital level (vs. profile slightly convex or straight). Differs from A. cordovae by presenting of 1–3 maxillary teeth (vs. none). It differs from A. gymnodontus by presenting 7–10 gill rakers on lower branch (vs. 11–13). Astyanax gymnogenys cannot be assigned to any of the Astyanax species complexes currently recognized within the genus. The following characters distinguish A. gymnogenys from the Astyanax species complexes: presence of a vertically elongate dark humeral blotch (vs. humeral blotch horizontally elongate, oval-shaped in the A. bimaculatus species complex, see Garutti & Langeani, 2009); presence of 20–26 anal-fin rays (vs. 25 or more in A. fasciatus species complex, see Melo & Buckup, 2006); body deepest at dorsal-fin origin (vs. deepest in area proximate to vertical at middle of pectoral fins in A. scabripinnis species complex, see Bertaco & Lucena, 2006).

Description. Morphometric data presented in Table 1 and range of meristic data in Table 2 . Maximum size 186.2 mm SL. Body elongated and compressed, deepest at dorsal-fin origin or slightly ahead. Head dorsal profile convex from margin of upper lip to vertical immediately before nostrils, straight to vertical through center of orbit, slightly to sharply concave from this point to tip of supraoccipital process. Dorsal profile convex from this point to end of dorsal fin, and slightly convex or straight between dorsal and adipose fins. Ventral profile convex between tip of lower lip to isthmus, straight or slightly convex from this point to vertical through preopercle, straight or slightly convex from latter point to origin of pelvic fin, and straight from latter point to base of anal fin terminus. Caudal peduncle with dorsal and ventral margins straight or slightly concave.

Mouth terminal or slightly subterminal. Maxillary bone extending beyond vertical through anterior margin of orbit, slightly curved and forming an angle of approximately 45º relative to longitudinal axis of body. Posteroventral margin of third infraorbital distant from margin of preopercle, leaving a broad naked area between edge of these bones, occupying more than 25% of depth of third infraorbital.

Premaxilla with two teeth rows, outer row with 2(6), 3*(46) or 4(25) teeth with three cusps, teeth cusps forming an arch with a convex profile in ventral view. Inner row with 4(3) or 5*(74) teeth, symphyseal teeth asymmetric with 2*(30), 3(38) or 4(4) cusps, teeth gradually decreasing in size, with cusps forming a straight line in ventral view; second and third teeth typically with three*, rarely four or five, cusps; fourth and fifth teeth always with three cusps. Maxilla with 1*(32), 2(36), or 3(8) teeth with three cusps. Dentary with 4*(28) or 5(27) anteriormost teeth larger, followed by four to nine abruptly smaller teeth; symphyseal teeth with three cusps and lateral larger teeth typically with three* cusps, rarely with four or five cusps; smaller teeth with three cusps or conical. Some specimens presenting dentary teeth decreasing in size gradually.

Dorsal-fin rays ii*(79), 9*(79) rays. First unbranched ray about half length of second ray. Distal margin of dorsal fin straight, its origin slightly anterior, or at midbody. Adipose fin at vertical through last anal-fin rays. Anal-fin rays with 17(4), 18(12), 19(27), 20*(17), 21(8) or 22(1) branched rays, last unbranched anal-fin ray and first and second branched rays longer than subsequente rays, forming a discrete anterior fin lobe. Origin of anal fin immediately posterior to vertical through origin of last dorsal-fin ray. Pectoral-fin rays i*(70), 11(1), 12*(14), 13(35), 14(17) or 15(3) rays, not reaching origin of pelvic fin when adpressed. Pelvic-fin rays i*(72), 6(1), 7*(22) or 8(49) rays, not reaching origin of anal fin when adpressed. Caudal fin forked, with lobes similar in size, with i,17,i*(79) principal rays. Dorsal procurrent rays 11(1) and ventral procurrent rays 10(1).

Scales cycloid. Lateral line complete, with 39(11), 40*(19), 41(25), 42(6) or 43(1) perforated scales. Series of scales above lateral line 7*(48) or 8(6), and 5(35) or 6*(17) below lateral line. Pre-dorsal scales 10(1), 11(1), 12(9), 13*(21), 14(18) or 15(5). Circumpeduncular scales 14*(34), 15(21), 16(4) or 17(3). Single row of scales covering base of anal fin with 5(1), 6(3), 7(5), 8(12), 9(15), 10(13), 11(2) or 12*(2) scales.

Supraneurals 6(1). Precaudal vertebrae 20(1), caudal 19(1), total vertebrae 39(1). Tip of first dorsal-fin pterygiophore behind neural spine of 11 th (1) vertebra and tip of last dorsal-fin pterygiophore before neural spine of 18 th (1). Tip of first anal-fin pterygiophore behind haemal spine of 21 st (1) vertebra and tip of last anal-fin pterygiophore before haemal spine of 30 th (1) vertebra. First gill arch with 6(19), 7*(49), or 8(7) upper gill rakers, one at the angle between upper and lower arches, and 7(2), 8(3), 9(43), or 10*(27) lower gill rakers.

Color in alcohol. Overall body color beige. Top of head darker. Infraorbitals, opercular area and pectoral girdle light brown. Dark chromatophores scattered on lateral portion of head, more densely concentrated on upper and lower lip, premaxilla, maxilla, infraorbitals, preopercle, and opercle.

A single dark, vertically-elongated humeral blotch, with dorsal portion wider, extending over three to four horizontal series of scales above the lateral line and two below. Portion of humeral blotch located dorsal to lateral line sometimes interrupted vertically by narrow clear stripe. Region immediately anterior and posterior to humeral blotch pale. Body with an inconspicuous grey midlateral stripe, extending from two to three scales on the rear of the humeral blotch to tip of caudal-fin rays, lighter in some specimens at posterior region of caudal peduncle and- or caudal-fin base. Chromatophores concentrated on posterior border of body scales, imparting a reticulate pattern. Scattered dark chromatophores widespread between lateral line and base of anal fin. Adipose fin beige, with few scattered dark chromatophores. Remaining fins with scattered chromatophores homogeneously distributed along the interradial membranes and edges of the rays ( Fig. 1 ).

Sexual dimorphism. Breeding tubercles were found on the head and edges of scales in males and females (NUP 2034, 2, 146.1–180.0 mm SL; NUP 2953, 3, 155.6–184.0 mm SL; NUP 5064, 1, 144.2 mm SL), as described in A. aramburui by Protogino et al. (2006). Fin hooks, the usual dimorphic feature among characids ( Gonçalves et al., 2005), were not found in any specimen collected in several months from January to December.

Distribution. Astyanax gymnogenys is only known from the middle and lower rio Iguaçu basin ( Fig. 2 ), states of Paraná and Santa Catarina, Brazil.

Material examined. 79 specimens (53.6–186.2 mm SL), all from Brazil, rio Iguaçu basin. Type-specimens. FMNH 54707, 64.9 mm SL, Santa Catarina, Porto União, rio Iguassú and flooded margins, swamps and lagoons, middle rio Iguaçu, ca. 26°14’52”S 51°05’25”W, 28 Dec 1908, J.D. Haseman. Holotype of Astyanax gymnogenys . FMNH 54708, 1, 65.1 mm SL, same data as previous. Paratype of Astyanax gymnogeny s. MZUSP 105954, 151.5 mm SL, Paraná, Laranjeiras do Sul, rio Iguaçu downstream from Salto Santiago dam, between Laranjeiras do Sul and Chopinzinho, lower rio Iguaçu, ca. 25°39’11”S 52°38’21”W, 5–10 Nov 1990, J.C. Garavello et al. Holotype of Astyanax longirhinus . MZUSP 105955, 1, 180.7 mm SL; NUP 10152, 15 of 16, 84.6–183.4 mm SL, Paraná State, Alto Alegre do Iguaçu, rio Iguaçu at Salto Caxias reservoir, lower rio Iguaçu, 25°30’00”S 53°24’59”W, 11 Jan 1994, Nupélia staff. Paratypes of Astyanax longirhinus . MZUSP 105956, 1, 170.3 mm SL, Santa Catarina State, Porto União at Colônia São Pedro, rio Timbó, middle rio Iguaçu, ca. 26°25’49”S 50°50’21”W, 20–22 nov 1986, J.C. Garavello et al. Paratype of Astyanax longirhinus . Non-types. Paraná State: NUP 595, 2, 143.0–167.0 mm SL, Foz do Jordão, Córrego Passo do Aterrado, affluent of rio Jordão, 25°45’13”S 52°05’09”W, 14 Oct 1995, COPEL staff. NUP 1580, 10, 74.2–150.9 mm SL, Reserva do Iguaçu, Segredo reservoir at rio Iguaçu, 25°47’47”S 52°08’07”W, 6 Nov 1995, Nupélia. NUP 2034, 15, 53.6–183.8 mm SL, Cruz Machado, Foz do Areia reservoir at rio Areia, tributary of rio Iguaçu, 26°00’33”S 51°39’52”W, 15 Aug 1993, Nupélia staff. NUP 2295, 2, 151.0– 173.7 mm SL, Reserva do Iguaçu, Segredo reservoir at rio Iguaçu, 25°47’47”S 52°08’07”W, 15 Jun 1999, COPEL staff. NUP 2953, 22, 61.4–186.2 mm SL, Cruz Machado, Foz do Areia reservoir at rio Areia, affluent of rio Iguaçu, 29 Dec 2002, Nupélia staff. NUP 5064, 1, 142.6 mm SL, Cruz Machado, Foz do Areia reservoir at rio Areia, affluent of rio Iguaçu, 26°00’33”S 51°39’52”W, 1 Oct 2006, GERPEL staff. NUP 11290, 4, 79.9–109.9 mm SL, Foz do Jordão, Salto Santiago reservoir at rio Iguaçu, 25°45’00”S 52°09’59”W, 26 Apr 2000, Nupélia staff. NUP 11858, 1, 103.8 mm SL, Cruz Machado, Foz do Areia reservoir at rio Areia, tributary of rio Iguaçu, 26°00’33”S 51°39’52”W, 15 Apr 2004, COPEL staff. Santa Catarina: LISDEBE 2622, 1, 142.8 mm SL, Porto União at Colônia São Pedro, rio Timbó, ca. 26°25’49”S 50°50’21”W, 7–9 Jun 1979, SURHEMA staff. NUP 17522, 1, topotype, 67.1 mm SL, Porto União, rio Iguaçu, 26°15’01”S 51°06’10”W, 11 Sep 2014, T. Dulz.

Figures

FIGURE 1. Astyanax gymmogenys, all from Brazil, Paraná State, rio Iguaçu basin: (a) FMNH 54707, holotype of A. gymnogenys, 64.9 mm SL, middle rio Iguaçu, Porto União. (b) FMNH 54708, paratype of A. gymnogenys, 65.1 mm SL, same locality of holotype. (c) NUP 17522, 67.1 mm SL, topotype. (d) NUP 11290, 79.9 mm SL; (e) NUP 11290, 82.6 mm SL; (f) NUP 11290, 109.9 mm SL, lower rio Iguaçu in Salto Santiago reservoir, Foz do Jordão. (g) MZUSP 105954, holotype of A. longirhinus, 151.5 mm SL, lower rio Iguaçu downstream from Salto Santiago reservoir, Laranjeiras do Sul.

FIGURE 2. Map of southeast South America showing the geographic distribution of Astyanax gymnogenys. Yellow star indicates the type-locality of A. gymnogenys, red star indicates the type-locality of A. longirhinus, and yellow dots remaining known localities for the species. “A” and “B” indicate the limits of upper and middle rio Iguaçu basin, respectively, according to Ingenito et al. (2004).

Tables

TABLE 1. Morphometrics of Astyanax gymnogenys. N = number of specimens.

		A. gymnogenys			A. longirhinus
Characters	Holotype	Paratype	Non-types	Mean	Holotype	Paratypes	Mean
			(N = 59)			(N = 9)
Standard length (mm)	64.9	65.1	53.6–186.2	98.1	151.5	84.6–183.0	139.7
Percentages of Standard Length
Predorsal distance	55.5	56.9	51.6–56.2	53.9	53.0	51.8–56.0	53.3
Prepelvic distance	–	51.0	49.0–52.2	50.7	51.0	48.4–53.4	51.2
Prepectoral distance	24.8	24.8	22.2–28.7	25.9	26.1	24.1–26.3	25.4
Preanal distance	69.5	71.4	66.1–71.3	69.1	69.1	66.2–73.4	69.0
Body depth	38.7	40.1	31.8–40.7	36.6	36.1	31.3–40.4	35.4
Caudal peduncle depth	11.7	12.1	10.2–12.2	11.1	11.2	9.9–12.1	10.9
Caudal peduncle length	14.6	15.2	13.2–16.4	14.9	13.1	13.0–16.0	14.7
Dorsal-fin length	28.7	27.9	21.3–27.7	24.2	24.0	21.1–26.5	23.4
Pelvic-fin length	17.7	18.0	14.5–18.0	16.1	16.4	14.5–17.0	15.5
Pectoral-fin length	17.8	17.9	18.6–23.2	21.4	22.0	18.7–23.0	20.5
Anal-fin length	21.6	15.8	15.3–19.9	17.5	15.8	15.3–19.7	17.0
Length of anal-fin base	24.7	22.3	19.3–22.6	21.4	22.1	18.9–23.9	21.4
Distance from eye to dorsal fin	40.7	42.0	38.8–42.9	41.2	41.1	39.2–42.5	40.8
Head length	27.9	28.8	23.8–30.8	27.2	26.9	24.9–27.0	26.5
Distance from pectoral-fin origin to pelvic-fin origin	–	–	23.6–29.8	25.6	26.1	25.6–28.5	27.0
Distance from pelvic- to anal- fin origins	20.2	20.2	17.9–21.2	19.8	18.9	16.4–22.7	19.2
Percentages of Head Length
Snout length	25.4	25.4	21.9–31.0	25.5	28.4	22.3–30.8	27.4
Upper Jaw	35.5	33.9	34.8–45.3	39.4	40.3	35.3–43.9	40.5
Orbital diameter	36.5	33.7	22.5–36.4	31.3	25.0	24.4–32.9	27.4
Interorbital distance	28.2	26.7	24.9–38.7	29.6	34.3	28.5–33.0	31.0