Leporinus elongatus Valenciennes, 1850

Britski, Heraldo A., Birindelli, José Luís O. & Garavello, Julio Cesar, 2012, A New Species Of Leporinus Agassiz, 1829 From The Upper Rio Paraná Basin (Characiformes, Anostomidae) With Redescription Of L. Elongatus Valenciennes, 1850 And L. Obtusidens (Valenciennes, Papéis Avulsos de Zoologia 52 (37), pp. 441-475 : 441-475

Leporinus elongatus Valenciennes, 1850

Figures 1 and 2

Leporinus elongatus Valenciennes , in Cuvier & Valenciennes, 1850:37 [in part: lectotype presumably from the Rio São Francisco (see Remarks), not paralectotype from Río de La Plata , Buenos Aires] – Günther, 1864:309 [catalog] – Fowler, 1950:231 [catalog] – Géry, Mahnert & Dlouy, 1987:394-396 [comments on the syntypes; designation of lectotype] – Garavello & Britski, 2003:75 [catalog] – Britski & Garavello, 2007:25 [catalog].

Leporinus crassilabris Borodin, 1929:274 , pl. 4, text-figure on page 274 [type locality: Rio Jaquitinhonha (= Rio Jequitinhonha ), Brazil] – Fowler, 1950:230, fig. 267 [catalog] – Garavello & Britski, 2003:75 [catalog] – Britski & Garavello, 2007:25 [catalog]. Syn. nov.

Leporinus crassilabris breviceps Borodin, 1929:275 [type locality: Rio Arassuahy (= Rio Araçuaí , tributary of Rio Jequitinhonha )] – Garavello & Britski, 2003:75 [catalog] – Britski & Garavello, 2007:25 [catalog]. Syn. nov.

Leporinus aff. bahiensis – Géry et al., 1987:387 [in part, only the specimen from Rio Jequitinhonha ( MHNG 2196-97)].

Material examined: Rio Jequitinhonha basin ( Brazil): MNHN 8624 (lectotype of Leporinus elongatus , 344.0 mm SL), Rio São Francisco. MCZ 20423 (holotype of Leporinus crassilabris , 91.0 mm SL), Rio Jequitinhonha ( Rio Jequitinhonha along the Jequitinhonha valley, 15°51’S, 38°53’W), April, 1866, C.F. Hart & E. Copeland (Thayer Expedition). MCZ 20422 (1 paratype of Leporinus crassilabris , 384.0 mm SL), Rio Jequitinhonha ( Rio Jequitinhonha along the Jequitinhonha valley, 15°51’S, 38°53’W), April, 1866, C.F. Hart & E. Copeland (Thayer Expedition). MCZ 20419 (holotype of Leporinus crassilabris breviceps , 359.2 mm SL), Rio Arassuahy ( Rio Araçuaí , tributary of the Rio Jequitinhonha , 17°00’S, 42°50’W), April 1866, C.F. Hart & E. Copeland (Thayer Expedition). MCZ 70505 (ex MCZ 20422a) (1, 294.0 mm SL), Rio Jequitinhonha ( Rio Jequitinhonha along the Jequitinhonha valley, 15°51’S, 38°53’W), April, 1866, C.F. Hart & E. Copeland (Thayer Expedition). MHNG 2196-97 (2, 44.7-72.2 mm SL), Rio Jequitinhonha, Itaobim , Minas Gerais, 27 Apr 1977, J.C. Garavello. MZUSP 2823 (5, 67.2-97.8 mm SL), Rio Jequitinhonha, Belmonte , Bahia, Jun 1919, E. Garbe. MZUSP 5136 (17, 18.2-53.2 mm SL), Rio Jequitinhonha (16°34’S, 41°29’W), Itaobim, Minas Gerais, 26 Jun 1966, Excursão do Departamento de Zoologia da Secretaria de Agricultura do Estado de São Paulo. MZUSP 74035 (1, 46.5 mm SL), marginal lagoon of Rio Jequitinhonha (16°08’S, 40°11’W), Minas Gerais, 22 Mar 1985, Expedição MZUSP / USNM. MZUSP 87847 (1, 132.9 mm SL), Rio Jequitinhonha (17°07’34”S, 42°58’45”W), Peixe Cru, Minas Gerais, 25 Apr 2003, F. Andrade & L. Rocha. MZUSP 93811 (4, 246.5-320.0 mm SL), Rio Jequitinhonha or Rio Araçuaí (purchased in the fish market), Araçuaí, Minas Gerais, 14 Apr 2007, J.L.O. Birindelli et al. MZUSP 106809 (19, 182.5- 276.9 mm SL), Rio Jequitinhonha , near Itira (16°47’S, 42°03’W), Araçuaí, Minas Gerais, 19 Feb 1989, J.C. Garavello et al. MZUSP 106740 (4, 226.8- 327.1 mm SL), Rio Jequitinhonha , below UHE Irapé (16°44’08”S, 42°34’27”W), Berilo, Minas Gerais, Nov 2009, F. Andrade & W. Santos. MZUSP 106810 (13, 184.5- 271.2 mm SL, 1 sk, 194.0 mm SL), Rio Jequitinhonha , near Itira (16°47’S, 42°03’W), Araçuaí, Minas Gerais, 19 Feb 1989, J.C. Garavello et al. MZUSP 106811 (7, 170.0-234.0 mm SL), Rio Jequitinhonha, V. Vono. MZUSP 106812 (1, 217.5 mm SL), Rio Araçuaí, J.C. Garavello. Rio Pardo ( Brazil): MZUSP 87882 (1, 179.2 mm SL), Rio Pardo, Berizal , Minas Gerais, 19 May 2000, B.P. Nogueira & G. V. Padilha. MZUSP 87883 (1, 150.5 mm SL), Rio Pardo, Berizal , Minas Gerais, 26 Jun 2000, B.P. Nogueira & G. V. Padilha.

Diagnosis: Leporinus elongatus is distinguished from all congeners, except L. amblyrhynchus , by having the combination of three teeth on each premaxilla and dentary (tooth formula 3/3) and 12 scale rows around the caudal peduncle (vs. tooth formulae 4/4, 3/4 or 4/3, and 14 or 16 scale rows around the caudal peduncle). Leporinus amblyrhynchus is distinguished from L. elongatus by having a dark longitudinal stripe along the lateral line (vs. three dark blotches on the lateral line in L. elongatus ). In addition, Leporinus elongatus is also diagnosed by having 36 or 37 pored scales on the lateral line, 4 scales rows from the dorsal-fin origin to the lateral line and 4 from the lateral line to the base of the pelvic fin.

Description: Morphometrics from type and non-type specimens are given in Table 1. Large sized species (largest examined specimen 384.0 mm SL). Body somewhat elongate, and moderately compressed, greatest body depth at dorsal-fin origin. Dorsal profile straight or slightly concave from snout tip to tip of supraoccipital spine; slightly convex from tip of supraoccipital spine to dorsal-fin origin; slightly concave along dorsal-fin base; somewhat straight from end of dorsal fin to adipose-fin origin, and concave from that point to origin of dorsal procurrent caudal-fin rays. Ventral profile gently concave from tip of lower jaw to vertical through pectoral-fin origin; convex from that point to anal-fin origin; somewhat straight along anal-fin base, and concave from anal-fin end to origin of ventral procurrent caudal-fin rays.

Head moderately elongate, snout moderately or extremely elongate. Mouth subterminal or subinferi- or, its cleft longitudinally aligned with ventral margin of infraorbitals or slightly below. Upper jaw extending anteriorly beyond lower jaw. Posterior end of maxilla approximately at vertical through posterior nostril. Premaxillary with three teeth decreasing gradually in size from symphyseal tooth. Dentary with three teeth also gradually decreasing in size from symphyseal tooth ( Fig. 3 ).

First gill arch with 11 (3), 12 (3) or 13 (1) gill rakers on lower limb, 1 (6) gill raker at angle, and 10 (2), 11 (2), 12 (2) or 13 (1) on upper limb.

Scales cycloid, seven to nine radii. Lateral line with 36* (18) or 37 (13) perforated scales, extending from posterior margin of opercle to base of median caudal-fin rays. Horizontal scale rows between dorsal-fin origin and lateral line 4* (30) or 5 (1). Horizontal scale rows between lateral line and pelvic-fin origin 4 (31). Horizontal scale rows around caudal peduncle (circumpeduncular scale series) 12 (31). Predorsal scales from dorsal-fin origin to tip of supraoccipital spine 10 (8), 11 (15) or 12 (2). Dorsal scales from dorsal-fin end to adipose-fin origin 10 (1), 11 (2), 12 (19) or 13 (8). Dorsal scales between adipose fin and first procurrent caudal-fin ray 6 (7), 7 (14) or 8 (5). Prepelvic scales 17 (1), 18 (4), 19 (11) or 20 (2). Scales from base of pelvic fin to anus 8 (4), 9 (11), 10 (2) or 11 (1). Ventral scales from anus to anal-fin origin 1 (18) or 2 (11). Ventral scales from anal-fin end to first ventral procurrent caudal-fin ray 6 (6), 7 (18) or 8 (2). Base of anal-fin rays covered by a row of four to seven scales.

Dorsal-fin rays ii,9 (3) or ii,10 (23). Dorsal fin origin slightly anterior to middle of standard length, and at vertical through second or third scale in front of pelvic-fin origin. Dorsal-fin distal margin gently convex. Last dorsal-fin ray split to its base (counted as a single element). Adipose fin small, its origin approximately at vertical through base of last two anal-fin rays. Pectoral-fin rays i,15 (4), i,16 (20) or i,17 (6). Tip of pectoral-fin rays extending to second or first scale in front of pelvic-fin origin (only reaching the latter in some specimens with less than 100 mm SL). Pelvic-fin rays i,8 (29) or i,9 (1). Pelvic-fin origin approximately at vertical through base of third or fourth branched dorsal-fin ray. Pelvic-fin tip reaching fourth or third scale in front of anus. Anal-fin rays ii,8 (27) or ii,9 (3). Anal-fin origin at vertical through fourth to sixth scale in front of adipose fin. Distal margin of anal fin straight or slightly concave. Anteriormost branched anal-fin ray about three times longer than posteriormost ray. Last anal-fin ray usually split to its base (counted as a single element). Principal caudal-fin rays i,8,9,i (30). Caudal fin forked, with lobes approximately similar in size or upper lobe slightly longer than lower lobe. Vertebrae 34 (1).

Coloration: Ground color light beige to light brown, darker dorsally. Three dark blotches on sides of body over lateral line, first below base of dorsal fin; second below space between dorsal-fin base and adipose-fin origin and third at posterior portion of caudal peduncle. Eight transverse dark bars on dorsal and lateral portions of body, some of them bifurcated dorsally; bars very conspicuous and extending ventrally in small specimens, becoming slightly faded in larger specimens, and disappearing completely in some individuals. Scales of lateral areas of body with diffuse chromatophores, more concentrated on free margins of scales. Fins nearly hyaline, with chromatophores tiny and scattered. Dorsal, adipose and caudal fins slightly darker than pectoral, pelvic and anal fins.

Live specimens ( Fig. 2B ) with lateral and dorsal portions of head and body silver or tan, ventral portions of head and body white, and fins dark yellow to orange.

Distribution: Known only from the Rio Jequitinhonha and Rio Pardo , rivers of the eastern region of Brazil in the states of Minas Gerais and Bahia ( Fig. 4 ). Although the Rio São Francisco was cited as the type locality in the original description, this record seems to be mistaken (see Remarks).

Remarks: Géry et al. (1987) designated the syntype of Leporinus elongatus collected by Saint Hilaire in the “riviere de San Francisco” as the lectotype of the species and suggested that it could have been collected in the Rio Jequitinhonha. Simultaneously , they suggested that Leporinus crassilabris , described by Borodin (1929) from the latter river, could be a synonym of L. elongatus . In the present contribution, we confirm Géry et al. (1987) ’s supposition and redescribe Leporinus elongatus on the basis of specimens from the Rio Jequitinhonha and Rio Pardo. In addition to the fact that the lectotype does not match specimens of Leporinus collected in the Rio São Francisco (see Britski et al., 1984, for descriptions of the species of Leporinus which occur in the latter drainage), some clues related to the collection of the specimen also corroborate our assumption that the type locality of the species is erroneous. Saint-Hilaire traveled in the province of Minas Gerais from September to November of 1817 stopping at different places in both Rio Jequitinhonha and Rio São Francisco basins ( Papavero, 1971). Specimens collected by Saint-Hilaire in one basin could be mistankenly labeled as coming from the other basin. Similar errors of locality in Saint-Hilaire’s collection were also pointed out by Lima (2002:133).

Géry et al. (1987) decided to select the specimen from the Rio São Francisco as the lectotype of Leporinus elongatus , arguing that if they had selected the specimen from Buenos Aires, then L. elongatus would have to be considered a junior synynom of L. obtusidens , and a taxonomic change would have to be made, which should be avoided for the sake of nomenclatural stability ( Géry et al., 1987:396). However, Géry et al. ’s selection of the specimen from the Rio São Franscisco , mandates a similar nomenclatural change, as Leporinus crassilabris now falls into the synonym of L. elongatus .

Borodin (1929) described Leporinus crassilabris breviceps as a subspecies because, although very similar and collected in the same river, the holotype of L. crassilabris breviceps has shorter snout, when compared to the three specimens he had identified as L. crassilabris ( MCZ 20423, holotype; MCZ 20422, paratype; MCZ 70505). In fact, the difference between those specimens is impressive ( Fig. 1B,D vs. Fig. 1C ) and deserves some considerations. Borodin (1929:274, pl. 4, figs. 1-5) designated a small-sized specimen ( MCZ 20423, 91.0 mm SL) as holotype of Leporinus crassilabris . However, Borodin (1929:275, text fig. 1) mentioned and illustrated the head of a large specimen ( MCZ 20422, 384 mm SL) of that species which has the snout much larger, and especially with fleshy and protruding lips (and this is also the case of MCZ 70505). Borodin (1929:275) then described the subspecies Leporinus crassilabris breviceps based on a specimen equivalent to the latter in size ( MCZ 20419, 359.2 mm SL), but with the snout and lips much smaller. Variations concerning snout shape (length of snout, position of mouth, lip thickness) are known to occur in conspecific individuals of Leporinus that may undergo strong changes with ontogenetic development (e.g., for L. reticulatus see Birindelli & Britski, 2009). Individuous of Leporinus elongatus appear to undergo this kind of change, as smaller specimens (e.g., holotype of L. crassilabris ) have the snout shorter when compared to larger specimens (e.g., paratype of L. crassilabris ). Nevertheless, some specimens of Leporinus elongatus of approximately the same size have the snout shape distinctly different ( Figs. 1 C-D, 5), as noted by Borodin (1929). This difference could be related to sexual dimorphism. However, we were not able to examine the sex of enough specimens with distinct snout shapes to conclude if this is the case. We were also unable to examine many specimens of extremely elongate snout and thick lips, perhaps because deep modifications of the snout take place only in individuals during spawning, who then undergo a reduction of the swollen tissue.

In addition, the paratype of Leporinus crassilabris (and MCZ 70505) seems to have not only an elongate snout but also extremely thick, tumescent and protruding lips ( Fig. 1D ). That could be due, at least partially, to conditions of preservation, i.e., being fixed in alcohol and conserved for long periods of time in the same liquid. This hypothesis was reinforced when we found one specimen of Leporinus amblyrhynchus Garavello & Britski, 1987 ( MZUSP 2006), collected in 1919, fixed in alcohol and preserved in the same fluid ( Fig. 6). This specimen presents the same kind of swollen snout shown in the MCZ aforementioned specimens, and is quite different from other conspecific individuals more recently preserved ( Fig. 6A). In this case the specimen remained for 92 years in alcohol, whereas the MCZ specimens stayed for about 70 years in similar conditions before Borodin’s studies. This would also explain why we could not find any other recently collected specimen of Leporinus elongatus with a similar modified snout shape.

Figures

FIGURE 1: (A) Lectotype of Leporinus elongatus, MNHN 8624, 344.0 mm SL, (B) holotype of L. crassilabris, MCZ 20423, 91.0 mm SL, (C) holotype of L. crassilabris breviceps, MCZ 20419, 359.2 mm SL, and (D) paratype of L. crassilabris, MCZ 20422, 384.0 mm SL.

FIGURE 2: Leporinus elongatus: (A) MZUSP 87883, 150.5 mm SL, Rio Pardo, and (B) UFMG uncatalogued, Rio Jequitinhonha, photographed live (photo by Francisco Andrade Neto).

FIGURE 3: Anterior portion of head of Leporinus elongatus, MZUSP 106810, 194.0 mm SL. Scale bar equals 10 mm.

FIGURE 4: Distribution map of Leporinus elongatus (yellow triangles), L. obtusidens (white squares), and L. piavussu (red circles).