A new species of Leporinus Agassiz , 1829 ( Characiformes : Anostomidae ) from the rio Tocantins , Brazil

A new species of Leporinus is described based on specimens from the lower rio Tocantins, Pará State, Brazil. The new species is diagnosed by having conspicuous dark spots on center of scales on anterolateral portion of body, 33 or 34 scales in lateral line, 16 scales rows around caudal peduncle, four scale rows between dorsal-fin origin and lateral line and four between lateral line and pelvic-fin origin, and four teeth on premaxilla and four on dentary. The new species is similar to Leporinus gomesi, L. granti, and L. nijsseni for having three prominent dark midlateral blotches, smaller blotches formed by dermal pigment, five of which form an interrupted “X” between head and first midlateral blotch, small dark spots formed by epidermal pigment, terminal mouth with four teeth on premaxilla and four on dentary, and relatively few scales on lateral line (less than 36). In addition, new data is provided for the type specimens of Leporinus granti and L. megalepis (=Hypomasticus megalepis),, and L. badueli is confirmed as a junior synonym of L. granti.


Introduction
The genus Leporinus Agassiz, 1829 is one of the most species-rich of the order Characiformes, with approximately 90 valid species (Garavello & Britski, 2003;Eschmeyer & Fricke, 2012).Recent field trips and increased study of specimens deposited in fish collections have revealed a still great number of undescribed species (e.g., Birindelli & Britski, 2009;Feitosa et al., 2011), as well as many taxonomic problems to be solved (e.g., Britski et al., 2011;Britski et al., 2012).Eigenmann (1912) described Leporinus granti based on specimens from his collections in Guyana, recognizing it as having many dark blotches over body.The species was latter redescribed by Garavello (1990), based on specimens from Guyana and rio Aripuanã, a tributary of rio Madeira in Brazil.In addition, Garavello (1990) described two similar species occurring with Leporinus granti: L. nijsseni from Guyana, and L. gomesi from rio Aripuanã.Géry et al. (1991) redescribed Leporinus granti and L. nijsseni based on specimens from French Guyana and considered L. badueli Puyo, 1948 a junior synonym of L. granti.The latter opinion was not followed by Garavello & Britski (2003) and Eschmeyer & Fricke (2012).
During the study of specimens of Leporinus at the Museu de Zoologia da Universidade de São Paulo, a new species of Leporinus similar to Leporinus gomesi in coloration and body shape was discovered.In addition, new information regarding the type series of Leporinus granti and L. megalepis Günther, 1863 (=Hypomasticus megalepis) was recently recovered.The aim of the present contribution is to describe the new species, to present new data on the type specimens of Leporinus granti, and L. megalepis, as well as to discuss the status of L. badueli.

Material and Methods
Counts and measurements were taken according to Britski & Garavello (1978) and Winterbottom (1980).Measurements were taken to the nearest 0.1 mm using dial calipers.Standard length (SL) is expressed in millimeters and all other measurements are expressed as percents of SL, except subunits of head, which are expressed as percents of head length.All counts were preferably made on the left side of the specimens.Meristic data are given in the description, with the frequency of each count provided between parentheses after the respective count, and an asterisk indicating counts of the holotype.Lateral-line scale counts included the pored scales extending onto base of the median caudal-fin rays; counts of the longitudinal scale rows above lateral line exclude the lateral-line scale row and the middorsal scale row; counts of the longitudinal scale rows below lateral line exclude the lateral-line scale row and include half a scale row when the pelvic-fin origin is immediately behind the middle of a scale.Vertebrae of the Weberian apparatus were counted as four elements and included in the vertebral counts; the fused PU1+U1 of the caudal region was counted as a single element.The pattern of radii was defined on scales immediately above lateral line row and at vertical through dorsal-fin origin.
All examined specimens are alcohol preserved, except when indicated by CS, which stands for cleared and stained specimens according to Taylor & van Dyke (1985)
Diagnosis.Leporinus santosi is distinguished from all congeners, except for L. gomesi, L. granti, and L. nijsseni, for having three prominent dark midlateral blotches, smaller blotches formed by dermal pigment, five of which form an interrupted "X" between head and first midlateral blotch, small dark spots formed by epidermal pigment, terminal mouth with four teeth on premaxilla and four on dentary, and relatively few scales on lateral line (less than 36).Leporinus santosi is further distinguished from all congeners, except L. gomesi, by having a conspicuous dark spots on the center of scales on anterolateral portion of the body (Figs.1a, b and 5a).
Leporinus santosi is distinguished from L. gomesi by having 16 (vs.12) scale rows around the caudal peduncle, and the second midlateral dark blotch rounded and not extended posteriorly to the vertical through the posterior margin of the adipose fin (vs.second midlateral dark blotch elongate, extended posteriorly to the vertical through the posterior margin of the adipose fin).
Description.Morphometric data in Table 1.Middle-sized, when compared to congeners; largest examined specimen 155.0 mm SL (MZUSP 32307).Head and body moderately compressed and relatively deep.Dorsal profile convex from snout tip to dorsal-fin origin, somewhat straight along dorsalfin base, straight and descending slightly from dorsal-fin end to adipose-fin origin, and usually concave from adipose-fin origin to anteriormost procurrent ray of caudal fin.Ventral profile convex from lower jaw to pelvic-fin origin, straight from latter point to anal-fin origin, convex along anal-fin base, and concave from anal-fin end to anteriormost procurrent ray of caudal fin.Greatest body depth at or slightly anterior to dorsal-fin origin.Mouth terminal, its cleft longitudinally aligned with middle of orbit in specimens up to approximately 60 mm SL, or to ventral margin of eye in larger specimens.Snout rounded, anteriorly blunt.Premaxilla with four (24) incisiform teeth gradually decreasing in size from symphyseal tooth.Dentary with four (24) incisiform teeth also gradually decreasing in size posterolaterally (Fig. 2).
Coloration.Ground color of head and body light brown, weakly countershaded.Head with one dark oblique stripe from top of snout, through eye, to posteriormost margin of opercle; one dark oblique stripe (sometimes faded) from upper lip, through ventral margin of eye, to ventral corner of preopercle; one dark spot between infraorbital 6 and dorsal margin of opercle.Body with three prominent dark round midlateral blotches (surrounding pale area), first one centered on vertical through base of last rays of dorsal fin, second one centered on vertical through base of anterior anal-fin  Body with many smaller dark round blotches formed by dermal pigment, including five blotches forming interrupted "X" between head and first midlateral blotch.In addition, center of each scale of anterolateral portion of body, between opercle and terminus of first midlateral blotch, with conspicuous dark spot formed by epidermal pigment; dark spots arranged in about eight longitudinal rows.Ventral surfaces of head and belly pale to cream.All fins predominantly hyaline.

Geographic distribution.
Leporinus santosi is known from a tributary of the rio Tocantins, at the stretch now inundated by the Tucuruí reservoir, and a tributary of the rio Itacaiúnas, a large tributary of the lower rio Tocantins (Fig. 3).
Etymology.Named in honor of Geraldo Mendes dos Santos, a researcher from INPA, for his important contributions to our knowledge of the fish fauna of the lower rio Tocantins, through his studies on the species of Anostomidae (Santos & Jégu, 1989), and on the impacts of the Tucuruí dam (Santos et al., 1984;Santos et al., 2004).An noun.

Discussion
The new species is similar to Leporinus granti (Fig. 4), L. gomesi (Fig. 5a), and L. nijsseni (Fig. 5b) for having three prominent dark midlateral blotches, smaller blotches formed by dermal pigment, including five forming an interrupted "X" between the head and the first midlateral blotch, and small dark spots formed by epidermal pigment, terminal mouth with four teeth on the premaxilla and usually four on the dentary (sometimes five in some specimens of L. gomesi, L. granti, and L. nijsseni), and relatively few scales in the lateral line (less than 36).Garavello (1990) described Leporinus granti based on specimens from the Essequibo River and the rio Aripuanã (rio Madeira drainage), and described Leporinus gomesi, sympatric with L. granti in the rio Aripuanã, and L. nijsseni, sympatric with L. granti in the Essequibo River.Géry et al. (1991) and Planquette et al. (1996) described Leporinus granti and L. nijsseni based on specimens from the French Guiana.Although all three species were accurately described and well diagnosed, we do have some comments concerning the type series of Leporinus granti, which was not entirely examined by Garavello (1990) and Géry et al. (1991).
Leporinus granti was originally described by Eigenmann (1912) based on nine specimens from Maripicru creek, a tributary of Ireng River, Guyana.The type specimens were catalogued in the Carnegie Museum (CM 1851, holotype, 144 mm TL [measurement given by Eigenmann]; CM 1839a, 1 paratype) and Indiana University (IU 12129, 7 paratypes, 108-185 mm TL [measurements given by Eigenmann]) (Eigenmann, 1912: 307)    Similarly, Leporinus megalepis (=Hypomasticus megalepis) was described based on three syntypes.One of the two paralectotypes of Leporinus megalepis (BMNH 1864.1.21.44, 92. mm SL) actually is a specimen of L. granti, by having terminal mouth with four teeth on premaxilla (vs.subinferior mouth and three teeth on premaxilla).The other diagnostic features of this specimen include 34 scales in lateral line, five scale rows between dorsal-fin origin and lateral line, 4.5 between lateral line and pelvic-fin origin, and 16 around caudal peduncle.The other paralectotype of Leporinus megalepis is a specimen of L. friderici (Bloch, 1794) by having large size, three midlateral blotches on body, 36 scales in lateral line, terminal mouth, and four teeth on premaxilla and four on dentary (in addition to 16 scale rows on caudal peduncle, four between dorsal-fin origin and lateral line and four between lateral line and pelvic-fin origin).The composite nature of the syntype series of Leporinus megalepis was previously noticed by Géry et al. (1988), who selected as the lectotype a specimen matching those identified as Leporinus maculatus Müller & Troschel, 1844by Eigenmann (1912).Their decision intended to preserve "la stabilité de la Nomenclature".If they had selected the syntype specimen that belongs to Leporinus granti, then L. granti would become a junior synonym of L. megalepis.On the other hand, if they had selected the specimen of Leporinus friderici to be the lectotype, then L. friderici would be senior synonym of L. megalepis.In both cases, the taxon, which we now commonly recognize as L. melagepis would be undescribed.By designating as the lectotype the syntype that belongs to L. megalepis, they successfully avoided the need of proposal of a new nominal species.However, due to their decision, L. badueli is now considered as a junior synonym of L. granti.
Leporinus badueli was described by Puyo (1948) based on two specimens (90 and 105 mm [SL?]) collected in the Mana River, French Guiana, that are currently lost.Based on Puyo's (1948: 81, text-figure)   rows between dorsal-fin origin and lateral line, and four rows between lateral line and pelvic-fin origin.The presence of five scale rows between dorsal-fin origin and lateral line is consistent with Leporinus granti, and unlike that of L. nijsseni.In addition, Planquette et al. (1996) and Sidlauskas & Vari (2012) recorded only Leporinus granti for the Mana River with L. nijsseni restricted in French Guiana to the Oyapoque River.Therefore, we agree with Géry (1977), Géry et al. (1988), andGéry et al. (1991) in considering Leporinus badueli as a junior synonym of L. granti.
description and illustration, the two type specimens of Leporinus badueli have coloration similar to L. granti and L. nijsseni, 34 or 35 scales in lateral line, five scale

Table 1 .
Morphometric data for Leporinus santosi.SD = Standard Deviation.rays, and third one on posterior half of caudal peduncle.Midlateral blotches decreasing in size posteriorly.Midlateral blotches formed by both dermal and epidermal pigments.