Characin

Occurs in ponds.

Cyphocharax platanus (Günther)

Curimatus platanus Günther, 1880:12 [type locality: Rio de La Plata].—Eigenmann Eigenmann, 1889:426 [reference]; 1891:47 [reference].—Eigenmann, 1907:451 [Argentina: Buenos Aires].—Eigenmann and Ogle, 1907:3 [Paraguay].—Eigenmann, 1910:422 [reference].—Marelli, 1923:557 [Argentina: lower Río Paraná and Río de La Plata systems].—Fowler, 1926:261 [Río de La Plata].—Devincenzi and Teague, 1942:59 [Uruguay].—Pozzi, 1945:271 [Río de La Plata].—Vari, 1989a, tables 2, 3 [assignment to Cyphocharax].

Curimata platana.—Fowler, 1943:312 [Rio Paraguay, Paysandu]; 1950:290 [literature compilation].—Nani, 1948:57, fig. 9 [redescription, discussion of parasites; Argentina: Rosario, Río Paraná; Concepción del Uruguay, Río Uruguay].—de Buen, 1949:85 [Uruguay].—Ringuelet and Aramburu, 1961:36 [Argentina].—Bertoletti, 1986:275 [Brazil: Rio Grande do Sul, Rio Uruguai basin].—Géry et al., 1987:415 [Paraguay: Río Paraná at Puerto Carlo Lopez and Campichuela; Argentina: Misiones, Río Paraná, Buenos Aires Province, Río de La Plata].

Curimatorbis platanus.—Fernández-Yépez, 1948:43 [assignment to Curimatorbis].—Ringuelet et al., 1967:194 [Río Paraná, Río Uruguay, Río de La Plata, Río Paraguay].—Bonetto, Cardiviola de Yuan, Pignalberi, and Oliveros, 1969:213 [Argentina; Río Paraná; not seen].—Bonetto, Cardiviola de Yuan, and Pignalberi, 1970:141 [middle Río Paraná; not seen].—Bonetto, Cardiviola de Yuan, Pignalberi, and Oliveros, 1970:135 [Argentina: middle Río Paraná; not seen].—Fowler, 1975:371 [reference].—Ringuelet, 1975:61, 65 [Río de La Plata, Río Paraná, Río Paraguay, Río Uruguay].—Miquelarcna, 1984:618, fig. 49 [caudal skeleton].—Cordiviola de Yuan and Pignalberi de Hassan, 1985:215 [Argentina: lower Río Paraná, Diamante and San Pedro areas].—Pignalberi de Hassan and Cordiviola de Yuan, 1985:21 [Argentina: middle Río Paraná, Corrientes and Santa Fe areas].—Lopez et al., 1987:19 [Argentina].—Pignalberi de Hassan and Cordiviola de Yuan, 1988:172 [Argentina: Formosa region, Oca Lagoon, number of specimens and biomass].

Curimatorbis platanum.—Lopez et al., 1984:74 [Argentina; Río Uruguay].

Cyphocharax platanus.—Bertoletti et al., 1990:40, 45, 52, 55, 58, 63, figs. 12, 13 [Brazil: Rio Grande do Sul, Rio Uruguay basin, foz do Rio Ijuí, Rio Ijuí-Mirim, Santo Izidro; common name]

DIAGNOSIS.—The 48 to 54 scales along the lateral line to the hypural joint, 10 to 13 scales in a transverse series from the lateral line to the origin of the dorsal fin, and 8 to 10 scales from the lateral line to the origin of the anal fin discriminate Cyphocharax platanus from the vast majority of members of the genus, all of which have 45 or fewer lateral-line scales, and 9 or fewer scales above and 7 or fewer scales below the lateral line, and from C. abramoides that has 77 to 97 lateral-line scales, and 24 to 30 scales above and 20 to 25 scales below the lateral line. The counts of scales in transverse series above and below the lateral line in C. platanus are similar to those of C. stilbolepis, but the species differ in number of lateral-line scales (48 to 54 in platanus versus 54 to 62 in stilbolepis), relative width of the orbit (0.25–0.29 of HL versus 0.31–0.34, respectively), relative distance from tip of snout to origin of anal fin (0.78–0.83 of SL versus 0.83–0.88), number of vertebrae (33 to 35 versus 32), and in the presence of a dark spot at the base of the middle rays of the caudal fin in C. platanus that is lacking in C. stilbolepis.

DESCRIPTION.—Body moderately elongate, laterally compressed, more so in specimens over 40 mm SL. Dorsal profile of head convex from upper lip to vertical line through posterior nostril, straight or very slightly concave from that line to tip of supraoccipital spine. Dorsal profile of body smoothly curved from tip of supraoccipital spine to origin of 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 indistinct median keel 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 indistinctly flattened, scales not enlarged relative to those on adjoining portions of body. Obtuse median keel posterior to origin of pelvic fin.

Greatest body depth at origin of dorsal fin, depth 0.31–0.37 [0.33]; snout tip to origin of dorsal fin 0.46–0.50 [0.46]; snout tip to origin of anal fin 0.78–0.83 [0.81]; snout tip to origin of pelvic fin 0.53–0.57 [0.53]; snout tip to anus 0.76–0.78 [0.76]; origin of dorsal fin to hypural joint 0.56–0.59 [0.59]. Dorsal fin pointed in profile, more rounded in larger specimens; last unbranched and first branched dorsal-fin rays approximately two and one-half times length of ultimate ray. Pectoral fin pointed in profile distally; length of pectoral fin 0.16–0.19 [0.16], tip of fin extends slightly beyond point three-quarters of distance to vertical line through origin of pelvic fin. Pelvic fin margin pointed in profile distally; length of pelvic fin 0.18–0.21 [0.19], reaches approximately three-quarters of distance to origin of anal fin in young adults, only slightly over one-half of distance in larger specimens. Caudal fin forked. Adipose fin well developed. Anal fin distinctly emarginate, anteriormost branched rays two and one-half to three times length of ultimate ray. Least depth of caudal peduncle 0.12–0.13 [0.13].

Head profile somewhat rounded anteriorly, distinctly pointed overall, head length 0.27–0.30 [0.27]; upper jaw longer than lower, mouth subterminal; snout length 0.27–0.32 [0.31]; nostrils of each side very close, anterior circular, posterior crescent-shaped with aperture closed by thin flap of skin separating nares; orbital diameter 0.25–0.29 [0.27]; adipose eyelid moderately developed, with broad, vertically ovoid opening over center of eye; length of postorbital portion of head 0.42–0.46 [0.43]; gape width 0.24–0.28 [0.24]; interorbital width 0.41–0.45 [0.44].

Pored lateral-line scales from supracleithrum to hypural joint 48 to 54 [51]; all scales of lateral line pored, canals in lateral-line scales straight; 3 to 5 series of pored scales extend beyond hypural joint onto caudal-fin base; 10 to 13 [11] scales in transverse series from origin of dorsal fin to lateral line; 8 to 10 [8] scales in transverse series from lateral line to origin of anal fin.

Dorsal-fin rays ii,9 or iii,9 (when three unbranched rays present, first very short) [ii,9]; anal-fin rays ii,7 or iii,7 (when three unbranched rays present, first very short) [ii,7]; pectoral- fin rays 13 to 16 [14]; pelvic-fin rays i,8 [i,8].

Total vertebrae 33 (1), 34 (23), 35 (1).

COLOR IN ALCOHOL.—Overall coloration of specimens retaining guanine on scales silvery or silvery-golden, darker on dorsal portions of head and body. Specimens lacking guanine on scales tan, darker dorsally. No pronounced pigmentation pattern on head or body. Horizontally elongate patch of dark chromatophores extends along midlateral surface of posterior portion of caudal peduncle and anterior section of bases of middle caudal-fin rays. Chromatophore patch extending six to eight scales horizontally and one and one-half to two scales vertically. Caudal-fin rays outlined by series of small, dark chromatophores. Other fins hyaline.

DISTRIBUTION.—Río de La Plata basin other than for upper Rio Paraná above Sete Quedas Falls (Figure 7).

COMMON NAME.—Brazil, Rio Grande do Sul: birú (Bertoletti et al., 1990:40).

MATERIAL EXAMINED.—61 specimens (36, 63.3–133.7).

ARGENTINA. Rio de La Plata, BMNH 1878.5.16:59, 1 (114.2, lectotype of Curimatus platanus Günther); BMNH 1878.5.16:60, 1 (111.7, paralectotype of Curimatus platanus Günther). Buenos Aires: Río de La Plata, Buenos Aires, ANSP 104624, 1 (114.7); GC, 1. Río Lujan at Escobar, GC, 1. Buenos Aires, USNM 176031, 3; NMW 67043, 2. Río Paraná, San Pedro, AMNH 12253, 2 (122.3–126.8). Missiones: Río Paraná, GC, 1. Formosa: Río Paraguay, BMNH 1971.2.12:3–16, 4 (63.3–75.6). Entre Ríos: Río Paraná, MZUSP 1705, 1. Santa Fe: Rosario, MCZ 790, 1.

URUGUAY. No exact locality, NMW 67033a, 6. Paysandú: Río Uruguay, Paysandu, ANSP 54101, 1 (86.0); MZUSP 21376, 1.

BRAZIL. Rio Grande do Sul: Rio Ibicuí, between Säo Rafael and Cacequi, MCP 9370, 5 (83.0–99.1). Rio Ibicuí, near mouth, Município de Itaqui, USNM 295976, 1 (133.7); MCP uncat., 1 (99.4); MZUSP 39784, 1 (117.4). Rio Uruguai, Itaqui, USNM 295979, 1 (125.0); MZUSP 1735, 3; MZUSP 1431, 2. Rio Uruguai, USNM 295977, 5 (83.1–90.9; 1 specimen cleared and counterstained for cartilage and bone). Itaqui, MZUSP 1735, 3.

PARAGUAY. No exact locality, USNM 55661, 1 (110.6). Central: Asunción Bay, USNM 295978, 1 (114.0).

Curimatus platanus Günther, 1880

Curimatus Nagelii Steindachner, 1882a

Curimatus microcephalus Eigenmann and Eigenmann, 1889b

Curimatus plumbeus Eigenmann and Eigenmann, 1889b

Curimatus spiluropsis Eigenmann and Eigenmann, 1889b

Curimatus gillii Eigenmann and Kennedy, 1903