Revision of the Neotropical trahiras of the Hoplias lacerdae species-group (Ostariophysi: Characiformes: Erythrinidae) with descriptions of two new species

Hoplias lacerdae was originally described from the rio Ribeira de Iguape, Iporanga, Sao Paulo State. The Hoplias lacerdae group is defined as containing generally large trahiras with the medial margins of dentaries running parallel to each other and lacking teeth on the basihyal compared to the H. malabaricus group in which the medial margins of the dentaries converge towards the mandibular symphysis and which have teeth on the basihyal. A taxonomic revision of the group based on meristic and morphometric data identified five distinct species: H. lacerdae distributed in the rio Ribeira de Iguape and rio Uruguai; H. intermedius from the rio Sao Francisco, upper rio Parana basin, and rio Doce; H. brasiliensis from rivers of the Atlantic Coastal drainage from the rio Paraguacu to the rio Jequitinhonha; H. australis new species, endemic to the rio Uruguai; and H. curupira new species present in northern South America, including the rios Negro, Trombetas, Tapajos, Xingu, Tocantins and Capim in the Amazon basin, upper rio Orinoco near the rio Casiquiare (Venezuela), and coastal rivers of Guyana and Suriname. A lectotype for Hoplias intermedius and a neotype for H. brasiliensis are designated. Hoplias lacerdae foi descrita originalmente do rio Ribeira de Iguape, Iporanga, Sao Paulo. O grupo Hoplias lacerdae foi definido como um conjunto de especies para abrigar as trairas geralmente de grande porte, com as margens mediais dos dentarios dispostas paralelamente e sem dentes no basi-hial, em oposicao as trairas do grupo Hoplias malabaricus, cujas margens mediais dos dentarios convergem em direcao a sinfise mandibular e possuem dentes no basi-hial. A revisao taxonomica do grupo baseada em dados meristicos e morfometricos identificou cinco especies distintas: Hoplias lacerdae distribuida nos rios Ribeira de Iguape e Uruguai; H. intermedius no rio Sao Francisco, alto rio Parana e rio Doce; H. brasiliensis nos rios costeiros da drenagem Atlântica, desde o rio Paraguacu ate o rio Jequitinhonha; H. australis especie nova, endemica ao rio Uruguai; e H. curupira especie nova no norte da America do Sul, incluindo os rios Negro, Trombetas, Tapajos, Xingu, Tocantins e Capim na bacia Amazonica; alto rio Orinoco proximo ao rio Casiquiare (Venezuela) e rios costeiros da Guiana e Suriname. Sao designados um lectotipo para Hoplias intermedius e um neotipo para H. brasiliensis.


Introduction
Species of the characiform genus Hoplias are distributed throughout of the many hydrographic systems of South America and are popularly known as trahiras, trairões (= big trahiras) or lobós.They inhabit a great number of habitats, ranging from lotic environments such as small to large rivers and waterfalls, to strictly lentic waters such as lakes and reservoirs.In all habitats they are predators of other fish (Taphorn, 1992;Planquette et al., 1996).Many species are important in subsistence and commercial fisheries in various regions of Brazil and other South American countries (Goulding, 1980).Species of Hoplias can achieve considerable size, and H. lacerdae and H. aimara are among the giants of the group, reaching up to one meter in total length.
The genus can be distinguished from all other characiforms by the following derived characters: (1) contact between the vomer and parasphenoid via interdigitations; (2) a mesethmoid with an anterior projection that separates the contralateral premaxillae; (3) the contact of the anterior parts of infraorbitals 2 and 5 with consequence exclusion of infraorbitals 3 and 4 from the orbital rim; (4) the posterior end of the maxilla with a large projection along its dorsal margin; (5) the expansion of the median region of haemal spine of the fifth vertebra; and (6) the absence of the ventral process of the third vertebra (Oyakawa, 1998).Oyakawa (1990) used morphological characters to define three species groups in Hoplias, a practice done in other characiform genera such as Acestrorhynchus (Menezes, 1992;Toledo-Piza, 1996) and Astyanax (Garutti & Britski, 1997).One of these groups within Hoplias was informally called the H. lacerdae group, which can be defined by the absence of toothbearing plates in the fleshy tissue on the dorsal surface of the basihyal and basibranchials (i.e.smooth tongue) and by the medial margins of contralateral dentaries lying almost parallel to each other, resulting in U-shaped margin in ventral view (Figs.1a-c).The second assemblage is the H. malabaricus group, that has still not been revised, but which can be recognized by the presence of tooth-bearing plates attached to fleshy covering on dorsal surface of the basihyal and basibranchials (i.e.rough tongue) and by having the medial margins of contralateral dentaries abruptly converging towards the mandibular symphysis thereby forming a V-shaped margin in ventral view (Fig. 1d).The third is the H. macrophthalmus group, which was recently revised (Mattox et al., 2006) and determined to contain a single species, Hoplias aimara.It is defined by the absence of an accessory ectopterygoid and the presence of a dark oval spot on the opercular membrane.
Eight species are considered valid in Hoplias (Oyakawa, 2003;Mattox et al., 2006), three of which were included by Oyakawa (1990) in the Hoplias lacerdae group: H. brasiliensis (Spix in Spix & Agassiz, 1829), H. microcephalus (Agassiz in Spix & Agassiz, 1829) and H. lacerdae Miranda-Ribeiro (1908).A fourth nominal species, Macrodon intermedius Günther (1864), was considered a junior-synonym of H. microcephalus (Oyakawa, 1990(Oyakawa, , 2003)).The number of specimens of the H. lacerdae group in ichthyological collections has greatly increased in recent decades, reflecting an expansion of its known geographic distribution throughout South America.The purpose of this paper is to review the species of the H. lacerdae group, redescribe the valid species and describe two new species of the group.

Material and Methods
This study was based on meristic and morphometric data from 467 specimens.Meristic data was taken under a stereomicroscope and the morphometric data was taken pointto-point with digital calipers to 0.1 mm.Measurements and counts were made on left side of body, whenever possible, and follow Fink & Weitzman (1974) and Mattox et al. (2006).Unbranched and branched fin-ray counts are presented as Roman and Arabic numbers, respectively.Osteological names follow Weitzman (1962) and Roberts (1969).Descriptions of coloration were based on specimens preserved in ethanol.An identification key to species of the Hoplias lacerdae group is presented with modal meristic values presented in brackets.Institutional abbreviations follow Ferraris (2007) with addition of UFRGS, Universidade Federal do Rio Grande do Sul.Diagnosis.The number of pores of the laterosensory canal along the ventral surface of dentary distinguished Hoplias australis from H. lacerdae (always 5 vs. 6-8 pores, respectively).The possession of an anterior profile of the head rounded in lateral view distinguished H. australis from H. brasiliensis and H. intermedius, which have the anterior profile of head angular.Hoplias australis can be further distinguished from H. curupira in the number of scales along lateral line (40-45 vs. 34-39 respectively).
Description.Morphometric data presented in Table 1.Body cylindrical, deeper than wide.Greatest body depth at vertical through third scale anterior to dorsal-fin origin in specimens smaller than 90 mm SL, and through sixth scale anterior to dorsal-fin origin in larger specimens (ca.220 mm SL).Anterior profile of head rounded in lateral view, but more angular in specimens smaller than 40 mm SL.Dorsal profile of head varying from slightly convex in specimens smaller than 40 mm SL to almost straight in larger individuals.Dorsal margin of orbit at horizontal through dorsal profile of head in specimens smaller than 40 mm SL, but not reaching dorsal profile of head in specimens larger than 90 mm SL.Dorsal profile of body convex from vertical through first series of scale to dorsal-fin origin; slightly straight and posteroventrally inclined along dorsal-fin base; slightly concave from vertical through base of last dorsal-fin ray to origin of dorsal most procurrent caudal-fin ray.Latter portion of profile slightly straighter in specimens smaller than 90 mm SL.Ventral profile of lower jaw distinctly angular in region of dentary symphysis, straight to slightly convex from vertical through anterior nostril to posterior margin of lower jaw.Medial margins of contralateral dentaries approximately parallel (Fig. 1a-c).Ventral profile of body slightly convex to pelvic-fin origin; approximately straight from latter point to anal-fin origin; straight and posterodorsally inclined along anal-fin base; slightly concave to straight from base of last anal-fin ray to anterior most ventral procurrent caudal-fin ray.
Upper jaw usually as long as lower jaw, but slightly shorter in some specimens.Posterior portion of maxilla dorsally enlarged and extending medially to anterior margins of second and third infraorbitals.Upper and lower lips fleshy with short skin projections covering canines externally.Anterior nostril tubular with anterior slit along its distal half.Anterior and posterior nostrils situated along horizontal through center of orbit, anterior nostril located at point two-thirds of orbital diameter from anterior margin of orbit.Posterior nostril situated closer to anterior nostril than to anterior margin of orbit.Eye proportionately larger in smaller specimens.Infraorbital bones well developed and horizontally elongate.Infraorbitals 3, 4, and ventral portion of 5 partially covering preopercle.Ventral margin of infraorbital 3 convex.Posterior margin of infraorbital 4 relatively straight and margins of infraorbitals 5 and 6 slightly convex.Small specimens (ca.90 mm SL) with infraorbital 3 barely reaching orbital rim and proximal portions of infraorbitals 2 and 4 almost in contact with each other.Larger specimens (ca.220 mm SL) with infraorbitals 3 and 5 completely excluded from orbital rim and infraorbital 4 barely reaching rim.
Teeth in both jaws conical or canine.Premaxillary teeth in   relatively small teeth.Dentary with anterior external row of teeth and posterior internal row.External series with three small anterior teeth followed by two well-developed canines, with posterior one larger.Posterior canine followed by 11 conical teeth, some half size of anterior most dentary canine.
Internal series beginning proximate to small conical tooth posterior to last conical tooth of external series and composed of approximately 12 very small teeth.Accessory ectopterygoid and ectopterygoid toothed; latter with series of small conical teeth along its ventrolateral margin and many smaller viliform teeth medially along its ventral surface.Endopterygoid edentulous.
Distal margins of all fins rounded.Total dorsal-fin rays 12-14 (n = 22; ii,10-12; mode: ii,11, n = 11).Dorsal fin located at midbody, its origin at vertical through approximately second scale anterior on series along pelvic-fin origin.Length of longest dorsal-fin rays two-thirds of body depth.Anal-fin base short.Total anal-fin rays 9-11 (n = 21; ii,7-9; mode: ii,8, n = 12).Tips of longest rays of depressed dorsal fin not extending beyond vertical through anal-fin origin.Total pectoral-fin rays 11-13 (n = 22; i,10-12; mode: i,11, n = 9).Pectoral-fin origin located at vertical through posterior region of opercle.Tip of pectoral fin separated from pelvic-fin origin by four to six scales, and falling short of vertical through dorsalfin origin.Pectoral, pelvic and anal fins of similar sizes.Pelvicfin rays i,7-8 (n = 22, i,8 in one specimen).Pelvic-fin origin situated at midbody and approximately three scales posterior of vertical through dorsal-fin origin.Tip of pelvic fin separated from vertical through anal-fin origin by three scales in specimens smaller than 90 mm SL, and by up to eight scales in larger specimens (ca.220 mm SL).Caudal-fin rays i,15,i (n = 9).
Well-developed, imbricated cycloid scales along body.Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine.Last vertical series of scales on caudal peduncle forming slightly convex arch on caudalfin base.Anterior margin of scales with small recess and posterior margin rounded.Approximately twelve radii extending from center of scale to its anterior margin and around twenty-two radii, some anastomosed, extending from center of scale to its dorsal, posterior and ventral margins.Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body.Lateral line with 40-45 perforated scales (n = 38, 44 in one specimen and 45 in one specimen; mode: 41, n = 12) (Table 2).Lateral-line scales with single laterosensory canal.Longitudinal series of scales between lateral line and dorsalfin origin 4. 5-5.5 (n = 21; mode: 4.5, n = 15).Longitudinal series of scales between lateral line and pelvic-fin origin 3. 5-5.5 (n = 20; mode: 4.5, n = 18).Longitudinal series of scales around caudal peduncle 19-20 (n = 21; mode 20, n = 20).
Approximately 12 gill rakers on first epibranchial, most in form of small denticulated plates.Lower branch of first branchial arch with five more elongate rakers and approximately 10 plate-like rakers (n = 9).Laterosensory canal along ventral surface of dentary always with five pores (n = 43, Table 3).Distribution.Throughout rio Uruguay basin, including its tributary rio Negro (Fig. 3).

Color in alcohol.
Etymology.The name australis, an adjective, refers to the southern range of this species, one of the southern most in the genus.
Remarks.Valenciennes (1846)   and slightly inclined from vertical through anterior nostril to posterior margin of lower jaw.Medial margins of contralateral dentaries running in parallel (Fig. 1a-c).Ventral profile of body slightly convex to pelvic-fin origin; approximately straight from latter point to anal-fin origin; straight and posterodorsally inclined along anal-fin base; slightly concave from last analfin ray to anterior most ventral procurrent caudal-fin ray.
Upper jaw slightly shorter than lower jaw.Posterior portion of maxilla dorsally enlarged and extending medial of anterior margins of second and third infraorbitals.Upper and lower lips fleshy with short projections of skin covering canines externally.Anterior nostril tubular with anterior slit along its distal half.Anterior and posterior nostrils situated along horizontal through center of orbit, anterior nostril two-thirds of orbital diameter from anterior margin of orbit; posterior nostril midway between anterior margin of orbit and anterior nostril.Eye proportionately larger in smaller specimens.Infraorbital bones well developed and horizontally elongate.Infraorbitals 3, 4, and ventral portion of 5 partially covering preopercle.Ventral margin of infraorbital 3 and posterior margins of infraorbitals 4, 5, and 6 convex.Small specimens (ca.35 mm SL) with infraorbital 3 excluded from orbital rim and proximal ends of infraorbitals 2 and 4 in contact.Larger specimens (ca.130 mm SL) with infraorbital 4 barely reaching orbital rim and infraorbital 5 gradually separated from rim.Proximal ends of infraorbitals 2 and 6 almost meeting in some of largest specimens (ca.280 mm SL).
Teeth in both jaws conical or canine.Premaxillary teeth in single row.First premaxillary tooth large canine, second, sixth and eighth teeth medium sized.Seventh tooth canine almost as large as anterior most premaxillary canine.Third to fifth and ninth premaxillary teeth small.Maxilla with single row of approximately 32 relatively small teeth, except for very welldeveloped canine-like fourth tooth.Dentary with anterior external row of teeth and posterior internal row.External series with four anterior small teeth, followed by two well-developed canines, with posterior canine larger than anterior canine and followed by 8 conical teeth slightly smaller than anterior most dentary canine.Internal series beginning at length of nearly one conical tooth posterior to last conical tooth of external row and formed of approximately 11 very small teeth.Accessory ectopterygoid and ectopterygoid toothed; latter with series of small conical teeth along its ventrolateral margin and with many smaller viliform teeth on its ventromedial surface.Endopterygoid edentulous.
Distal margins of all fins rounded.Total dorsal-fin rays 12-14 (n = 75; ii,11; ii,10 in two specimens and ii,12 in five specimens).Dorsal fin located at midbody, its origin at vertical through approximately third scale anterior on series along pelvic-fin origin.Length of longest dorsal-fin rays two-thirds of body depth.Anal-fin base short.Total anal-fin rays 9-10 (n = 75; ii,8, ii,7 in five specimens).Tip of depressed dorsal fin reaching vertical through anal-fin origin.Specimens smaller than 35 mm SL with tip of anal fin (third to sixth branched rays) reaching origin of anterior most ventral procurrent ray of caudal fin.Total pectoral-fin rays 12-14 (n = 70; i,11-13; mode: i,12, n = 40).Pectoral-fin origin located at vertical through central portion of opercle.Tip of pectoral fin separated from pelvic-fin origin by four to six scales.Pectoral and pelvic fins of similar size and slightly larger than anal fin.Pelvic-fin rays i,7 (n = 75, i,5 in one specimen).Pelvic-fin origin situated at midbody approximately three scales posterior to vertical through dorsal-fin origin.Tips of pelvic fin separated from vertical through anal-fin origin by four or five scales.Caudal-fin rays i,15,i (n = 71, 14 branched rays in one specimen).
Well developed cycloid scales imbricated along body.Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine.Last vertical series of scales on caudal peduncle forms slightly convex arch on caudal-fin.Anterior margin of scales with small recess and posterior margin rounded.Approximately twelve radii extending from center of scale to its anterior margin and around twenty-five radii, some anastomosed, extending from center of scale to dorsal, posterior and ventral margins.Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body.Lateral line with 38-43 perforated scales (n = 74, 38 in two specimens; mode: 41, n = 24) (Table 2).Lateral-line scales with single laterosensory canal.Longitudinal series of scales between lateral line and dorsal-fin origin 5.5 (n = 75).Longitudinal series of scales between lateral line and pelvic-fin origin 4.5-5.5 (n = 75; mode: 5.5, n = 72).Longitudinal series of scales around caudal peduncle 18-20 (n = 73; 18 scales in two specimens).Approximately eight gill rakers on first epibranchial, most in form of small denticulated plates.Lower branch of first branchial arch with five or six more elongate rakers and approximately 10 plate-like rakers (n = 8).Laterosensory canal along ventral surface of dentary with 4-6 pores (n = 75; mode: 5, n = 66) (Table 3).
Color in alcohol.Ground coloration of head and body dark to light brown, darker dorsally and paler ventrally.Single dark midlateral stripe along lateral line separating dark dorsal from lighter ventral region.Stripe more evident in specimens smaller than 130 mm SL, the only color feature in very small specimens (ca.35 mm SL).Specimens larger than 100 mm SL with five or six dark blotches along dark longitudinal stripe, some of them connected with contralateral blotch by dark dorsal saddle.Dorsal surface of head dark brown.Lips with alternating dark and light, thin, vertical bands.Ventral surface of head white.Coloration of infraorbital region and dorsal surface of head similar.Many specimens with two dark stripes radiating posteriorly from eye across opercular series and with third dark stripe extending posteroventrally from eye along infraorbital 2. Ground coloration of opercular series dark brown.Opercular membrane usually lighter than opercle.
All fins light brown and lighter than body, with dark spots on rays and interradial membrane forming pattern of irregular dark stripes.Stripes of anal and caudal fins wider than those of dorsal fin with stripes more irregular in anal fin.Pectoral, pelvic, and anal fins with paler pattern than dorsal and caudal fins.Ventral surfaces of pectoral and pelvic fins either lighter than, or with same pattern, as dorsal surface of fin, but with pattern less conspicuous.
Distribution.Coastal rivers of northeastern Brazil, from the rio Paraguaçú in Bahia State to rio Jequitinhonha in Minas Gerais and Espírito Santo States, including rio de Contas and rio Pardo (Fig. 3).Spix & Agassiz (1829) to describe Erythrinus brasiliensis and deposited in the Zoologische Staatssammlung München, were destroyed during a bombing raid in the Second World War (Terofal, 1983;Kottelat, 1988;Neumann, 2006).The holotype of Erythrinus brasiliensis is not among the specimens studied by Spix & Agassiz in the Musée d'Histoire Naturelle, Neuchâtel, and is therefore judge to be missing.Its original description, however, mentioned the "tongue […] edentate" and "branches of the lower jaw rather distant from each other and somewhat spread out below […] parallel to one another" [our translation].These observations confirm that E. brasiliensis is a member of the Hoplias lacerdae group.Data presented in this study match the remaining information in the original description.Since the holotype of E. brasiliensis is lost, and in order to clarify the taxonomic status of this nominal species, a neotype is designated in accordance to Article 75 of the International Code of Zoological Nomenclature (ICZN, 1999).The taxon is redescribed herein, with characters diagnosing it from other members of the genus.

Remarks. Specimens used by
Castelnau (1855) identified some specimens collected in the rio Carandaí, a tributary of rio das Mortes, Minas Gerais State, as Erythrinus brasiliensis and stated that the specimens attained 50 cm SL.According to the results of the present study, Hoplias brasiliensis attains only 30 cm SL, being the smallest among species of the H. lacerdae group.The river mentioned by Castelnau (1855) belongs to the rio Grande basin, upper rio Paraná, and the available name for the specimens cited by that author is H. intermedius, a form that can reach 50 cm SL.

Hoplias curupira, new species
Fig. 5 Hoplias    large as anterior most premaxillary canine.Third to fifth, eighth, and ninth premaxillary teeth small.Maxilla with single row of approximately 33 relatively small teeth, except for very well developed canine-like fourth tooth.Dentary with anteriorly, external row of teeth and posterior internal row.External series with three anterior small teeth, followed by two well developed canines, with posterior canine larger than anterior canine, and then 13 conical teeth.All slightly smaller than anterior most dentary canine.Internal series beginning at level of last conical tooth of external series and composed of approximately 16 very small teeth.Accessory ectopterygoid and ectopterygoid toothed.Ectopterygoid with series of small conical teeth along its ventrolateral margin and many smaller viliform teeth ventromedially.Endopterygoid edentulous.
Distal margins of all fins rounded.Total dorsal-fin rays 13-16 (n = 154; ii,11-14; mode: ii,12, n = 84).Dorsal fin located at midbody, its origin at vertical through approximately third scale anterior on series along pelvic-fin origin.Length of longest dorsal-fin rays slightly more than one-half of body depth.Anal-fin base short.Total anal-fin rays 8-10 (n = 155; ii,6-8; mode: ii,8, n = 148).Specimens larger than 160 mm SL with tip of depressed dorsal fin extending beyond vertical through anal-fin origin.Few specimens with longest anal-fin rays (third-to sixth branched rays) reaching origin of anterior most ventral procurrent ray of caudal fin.Total pectoral-fin rays 11-14 (n = 153; i,10-13; mode: i,11, n = 83).Pectoral-fin origin located at vertical through posterior region of opercle.Tip of pectoral fin separated from pelvic-fin origin by four or five scales, and almost reaching vertical through dorsal-fin origin in some specimens larger than 160 mm SL.Pectoral, pelvic and anal fins of similar size.Pelvic-fin rays i,7 (n = 154, i,6 in three specimens).Pelvic-fin origin situated at midbody and approximately three scales posterior to vertical through dorsal-fin origin.Tips of pelvic fin separated from vertical through anal-fin origin by three or four scales.Caudal-fin rays i,14-16,i (n = 145, 14 branched rays in seven specimens and 16 branched rays in one specimen).
Well developed cycloid scales imbricated along body.Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine.Last vertical series of scales on caudal peduncle forms slightly convex arch on caudal-fin base in lateral view.Anterior margin of scales with small recess and posterior margin rounded.Approximately eight radii extending from center of scale to its anterior margin and around eleven radii, some anastomosed, extending from center of scale to its dorsal, posterior, and ventral margins.Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body.Lateral line with 34-39 (n = 143, 39 in three specimens; mode: 36, n = 60) perforated scales (Table 2).Lateral-line scales with single laterosensory canal.Longitudinal series of scales between lateral line and dorsal-fin origin 4.5-5.5 (n = 152; mode: 4.5, n = 112).Longitudinal series of scales between lateral line and pelvic-fin origin 4.5-5.5 (n = 150; mode: 4.5, n = 146).Longitudinal series of scales around caudal peduncle 18-20 (n = 150; mode 20, n = 144).
Approximately 11 gill rakers on first epibranchial, most in form of small denticulated plates.Lower branch of first branchial arch with four to seven more elongate rakers and approximately 10 plate-like rakers (n = 148).Laterosensory canal along ventral surface of dentary in form of four well defined patches of several small pores in specimens larger than 100 mm SL (Fig. 1c); usually four pores of laterosensory canal, and some pores divided in two or three smaller pores, in specimens around 50 mm SL (Fig. 1a).Pores gradually more divided in specimens between 60-80 mm SL (Fig. 1b) (Table 3).

Color in alcohol.
Ground coloration of head and body dark brown, darker dorsally and paler ventrally.Ventral region almost as dark as dorsal portion in several specimens.Dark reticulated pattern present in specimens smaller than 20 mm SL; pattern expanding and becoming darker in larger specimens (ca.90 mm SL), covering most of body in some of largest examined individuals.Dorsal surface of head dark brown, slightly lighter than remaining dorsal surfaces of body in some specimens, often with lighter reticulated pattern.Lips dark brown with alternating dark and light vertical bands in some specimens.Coloration of infraorbital region and dorsal surface of head similar.Many specimens with one or two dark stripes radiating posteriorly from eye across opercular series, more conspicuously in specimens with light brown coloration.Ground coloration of opercular series dark brown.Opercular membrane with same pattern as opercle.
All fins light brown to dark grey with white spots on rays and interradial membrane forming pattern of irregular light stripes.Three or four white stripes on dorsal fin, five white stripes on caudal fin and approximately four white stripes on anal fin.Ventral surfaces of pectoral and pelvic fins with same pattern as dorsal surfaces.
Distribution.Rivers of the Amazon basin including rios Capim, Tocantins, Xingu and Tapajós on the right bank of the rio Amazonas and rios Trombetas and Negro on the left bank, including upper tributaries of the rio Negro (rios Tiquié and Uaupés).In the rio Orinoco basin, Hoplias curupira occurs in the upper Orinoco, near the río Casiquiare.The species also occurs in coastal rivers of Guyana and Suriname, such as Essequibo, Demerara and Nickerie Rivers (Fig. 3).
Etymology.The specific name curupira, a noun in apposition, refers to the Curupira, a mythical creature of the Brazilian folklore that protects the forest.A Curupira is a small Amerindian child who has its feet turned backwards, making it difficult to follow its tracks.
Remarks.The distribution of Hoplias curupira greatly overlaps that of H. aimara, with the exception that the latter species is unknown from the rio Negro basin (including rio Branco) and upper rio Orinoco.These two species, however, do not seem to occur syntopically, as H. aimara is found predominantly in rapids and waterfalls (Mattox et al., 2006) while H. curupira prefers large rivers and igarapés (Lima et al., 2005).Despite the evident differences between these two taxa (see above), specimens of H. aimara are commonly mistaken as H. aff.lacerdae (= H. curupira) in fishing magazines.Our data show that H. curupira does not grow as large as H. aimara, the true large trahira that is regarded as a good sport fish and pursued by anglers in Amazonian rivers such as rio Xingu.
Although most of the morphometric data from specimens presented herein overlap among different species, two characters can be used to diagnose H. curupira from congeners.Specimens of the taxon have broader heads compared to the remaining four species in the Hoplias lacerdae group, with this reflected in the snout width (13.1-27.2% of head length) (Fig. 6) and the interorbital width (16.0-35.5% of head length) (Fig. 7), vs. the remaining species of the group (12.6-22.9% and 14.9-30.1% of head length respectively).The mean relative snout width of H. curupira is 23.2% (standard deviation = 2.7) vs. 18.7% (standard deviation = 1.9) in the remaining species of the Hoplias lacerdae group, and the mean relative interorbital width of H. curupira is 27.9% (standard deviation = 4.1) vs. 21.1% (standard deviation = 2.9) in the remaining species of Hoplias lacerdae group.Hoplias curupira is often referred as "cabeça chata" (flat headed), in reference to the larger width of its head compared to other species of Hoplias.
Hoplias curupira has a wide distribution in the Amazon Basin, and variation of the color pattern was detected from different localities.It is not possible, however, to define if this is due to ecological variation or indicative of a second species in the basin.Therefore the type series was restricted to rio Tocantins basin.
According to Lima et al. (2005), Hoplias curupira occurs in large rivers and igarapés, exhibits diurnal as well as nocturnal habits, is often seen in pairs, and probably spawns inside hollow logs.It feeds on various insects, larvae, small fishes, shrimps and worms, and also eats certain fruits.Diagnosis.Hoplias intermedius differs from the others species of the H. lacerdae group, but H. australis and H. lacerdae, in the number of scales along lateral line (42-46 vs. 38-43 in H. brasiliensis and 34-39 in H. curupira).It can be further distinguished from H. australis and H. lacerdae, in the number of pores of the laterosensory system along the ventral surface of dentary (4-6 vs. always 5 and 6-8 respectively).The shape of anterior profile of head further distinguished H. intermedius from H. australis (angular vs. rounded respectively).).Dorsal profile of body slightly convex from vertical through first series of scale of body to dorsal-fin origin; straight and posteroventrally inclined along dorsal-fin base; straight and less inclined to slightly concave from vertical through base of last dorsal-fin ray to origin of dorsal most procurrent caudal-fin ray.Ventral profile of lower jaw distinctly angular in region of mandibular symphysis, straight to slightly inclined from vertical through anterior nostril to posterior margin of lower jaw.Medial margins of contralateral dentaries running in parallel (Fig. 1a-c).Ventral profile of body slightly convex to pelvic-fin origin; approximately straight to slightly convex from latter point to anal-fin origin; straight and posterodorsally inclined along anal-fin base; slightly concave from base of last anal-fin ray to anterior most ventral procurrent caudal-fin ray.

Description. Morphometric data presented in
Upper and lower jaws of similar size in specimens smaller than 40 mm SL, upper jaw gradually becoming shorter than lower jaw in larger specimens.Posterior portion of maxilla dorsally enlarged and extending medial to anterior margins of second and third infraorbitals.Upper and lower lips fleshy with short projections of skin covering canines externally.Anterior nostril tubular with anterior slit along its distal half.Anterior and posterior nostrils situated along horizontal through center of orbit, anterior nostril located at two-thirds of orbital diameter from anterior margin of orbit; posterior nostril situated midway between anterior nostril and anterior margin of orbit.Eye proportionately larger in smaller specimens.Infraorbital bones well-developed and horizontally elongate.Infraorbitals 3, 4, and ventral portion of 5 partially covering preopercle.Anteroventral margin of infraorbital 3 relatively straight and posteroventral margin convex.Posterior margin of infraorbitals 4, 5, and 6 slightly convex.Small specimens (ca.40 mm SL) with infraorbital 3 barely reaching orbital rim and proximal ends of infraorbitals 2 and 4 almost in contact.Larger specimens (ca.130 mm SL) with infraorbitals 3 and 4 completely excluded from orbital rim and infraorbital 5 progressively separated from rim in larger specimens.Proximal ends of infraorbitals 2 and 6 almost meeting in some of the largest specimens examined (ca.300 mm SL).
Teeth in both jaws conical or canine.Premaxillary teeth in single row.First premaxillary tooth large canine, second and seventh teeth medium sized.Eighth tooth canine almost as large as anterior most premaxillary canine.Third to sixth, and ninth premaxillary teeth small.Maxillary with single row of approximately 32 relatively small teeth, except for very well developed canine-like fourth tooth.Dentary with anterior external row of teeth and posterior internal row.External series with three anterior small teeth, followed by two well developed canines with posterior canine larger than anterior canine, and then 11 conical teeth slightly smaller than anterior most dentary canine.Internal series beginning at level of last conical tooth of external row and composed of approximately 18 very small teeth.Accessory ectopterygoid and ectopterygoid toothed.Ectopterygoid with series of small conical teeth along ventrolateral margin and many smaller viliform teeth on ventromedial surface.Endopterygoid edentulous.
Distal margins of all fins rounded.Total dorsal-fin rays 13-15 (n = 98; ii,11-13; mode: ii,12, n = 44).Dorsal fin located at midbody, its origin at vertical through approximately fourth scale anterior on series along pelvic-fin origin.Longest dorsalfin ray approximately three-quarters of body depth.Anal-fin base short.Total anal-fin rays 9-11 (n = 97; ii,7-9; mode: ii,8, n = 88).Tip of depressed dorsal fin reaching vertical through anal-fin origin in small specimens (< 130 mm SL) but falling short of that point in larger specimens.Total pectoral-fin rays 12-14 (n = 89; i,11-13; mode: i,11, n = 55).Pectoral-fin origin located at vertical through median region of opercle.Tip of pectoral fin separated from pelvic-fin origin by four to six scales.Pectoral and pelvic fins of similar size and slightly smaller than anal fin.Pelvic-fin rays i,7 (n = 97, i,8 in one specimen).Pelvic-fin origin situated at midbody and approximately four scales posterior to vertical through dorsalfin origin.Tip of pelvic fin separated from vertical through anal-fin origin by four or five scales.Caudal-fin rays i,15,i (n = 88, 13 branched rays in one specimen and 14 branched rays in six specimens).
Well developed cycloid scales imbricated along body.Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine.Last vertical series of scales on caudal peduncle forms slightly convex arch on caudal-fin base in lateral view.Anterior margin of scales with small recess and posterior margin rounded.Approximately eight radii extending from center of scale to its anterior margin and around eighteen radii, some anastomosed, extending from center of scale to its dorsal, posterior, and ventral margins.Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body.Lateral line with 42-46 (n = 90, 42 in five specimens and 46 in four specimens; mode: 44, n = 36) perforated scales (Table 2).Lateral-line scales with single laterosensory canal.Longitudinal series of scales between lateral line and dorsalfin origin 5.5-6.5 (n = 92; mode: 5.5, n = 86).Longitudinal series of scales between lateral line and pelvic-fin origin 4. 5-5.5 (n = 93; mode: 5.5, n = 75).Longitudinal series of scales around caudal peduncle 20 (n = 92).
Color in alcohol.Ground coloration of head and body dark to light brown, darker dorsally and paler ventrally.Ventral region white in several specimens.Approximately seven dark parallel diagonal bars along dorsal region, bars extending anteroventrally to just below lateral line.Diagonal bars in many specimens continuing posteroventrally to approximately two longitudinal scale series below lateral line, resulting in chevron-like pattern.Dorsal portions of bars more evident than ventral region.Bars more conspicuous in specimens with light brown ground coloration.Dorsal surface of head dark brown.Lips with alternating dark and light vertical bands, but completely black in some of largest specimens examined (ca.300 mm SL).Ventral surface of dentaries varying from white in small specimens (ca.40 mm SL), to alternating dark and light transverse stripes in specimens around 130 mm SL, to completely dark in larger specimens.Coloration of infraorbital region and dorsal surface of head similar.Many specimens with two dark stripes radiating posteriorly from eye along infraorbital 6 and dorsal portion of infraorbital 3. Ground coloration of opercular series dark brown.Opercular membrane usually lighter than opercle.
All fins light brown, lighter than body in specimens smaller than 130 mm SL, with dark spots on rays and interradial membranes forming pattern of irregular dark stripes.Stripes on anal and caudal fins wider and more regular than those on dorsal fin.Ventral surfaces of pectoral and pelvic fins either lighter than, or with same pattern as, dorsal surface, but with pattern less conspicuous.Fins of largest specimens (ca.300 mm SL) usually darker than rest of body.
Distribution.In the rio São Francisco basin and upper reaches of rio Paraná basin, including rios Grande, Paranaíba and Piquiri.Hoplias intermedius also occurs in tributaries of rio Doce, Minas Gerais State (Fig. 3).
Remarks.Syntypes of Macrodon intermedius are deposited in the BMNH collection, and permit its clear placement in the Hoplias lacerdae group.Data presented herein matches information from the original description of M. intermedius.Oyakawa (1990) included the nominal species Erythrinus microcephalus Agassiz, 1829 and Macrodon intermedius Günther, 1864 in the Hoplias lacerdae group, with latter being considered a junior synonym of the former (Oyakawa, 2003).These names are available for the taxon occurring in the upper rio São Francisco drainage, since E. microcephalus was described from "rio São Francisco" and M. intermedius from "rio Cipó", one of its tributaries.As discussed above, many specimens of species described by Spix and Agassiz (1829) were lost during World War II, as well as the holotype of Erythrinus microcephalus is also missing (Terofal, 1983;Kottelat, 1988).Unlike the situation with Erythrinus brasiliensis (see above), the original description of E. microcephalus, although mentioning that the tongue is edentate, is unclear as to the alignment of the contralateral dentaries noting only that "branches of the lower jaw narrow and convex throughout their length, farther apart when the mouth is closed and distant from the other by a greater space than their transverse diameter" [our translation].This makes it difficult to determine whether Hoplias microcephalus belongs to the H. lacerdae or to the H. malabaricus species groups.Neither Hoplias microcephalus nor H. intermedius have been recently used, except for a catalog based on preliminary data (Oyakawa, 2003), but previous authors included both epithets as synonyms of H. malabaricus (e.g.Steindachner, 1874;Lütken, 2001).The younger name, H. intermedius is certainly a member of the H. lacerdae group whereas the older one, H. microcephalus cannot be unambiguously assigned to this group.Since neither these names has been used recently, H. intermedius is herein chosen to designate this taxon.
Hoplias intermedius has an interesting disjunct distribution, occurring in the upper stretches of rio São Francisco, rio Doce and rio Paraná.In the latter basin, the species is not known to occur downstream of the Sete Quedas.Similar distributions are reported for other fish species (Menezes, 1988;Vari & Harold, 2001).Dergam et al. (2002)  Current knowledge of the geological history of eastern South America indicates that the origin of coastal rivers involved successive erosion of the eastern margin of the platform associated with consequent upland river capture, giving rise to the various independent basins draining into the Atlantic Ocean (Potter, 1997;Ribeiro, 2006).According to these authors, six major uplift events created megadomes that worked synergistically with marginal erosion and upland stream capture along the Atlantic coast of South America when the latter and Africa were separated during the opening of the Atlantic Ocean.One of these megadomes, the "Mantiqueira-Angola", is represented in Brazil by highlands extending from São Paulo and Rio de Janeiro states north to Minas Gerais state, and was responsible for isolating the upper stretches of the rios São Francisco, Paraná and Doce.Therefore, it is possible that the disjunct distribution pattern of Hoplias intermedius, as well as of other examples cited above, results from a common history of these basins.
Goeldi (1898) cited Macrodon intermedius in the Ilha de Marajó, in the mouth of rio Amazonas.Under current understanding of the distribution of H. intermedius it is clear that these records of the species in the Amazon basin were based on misidentifications.The only species of H. lacerdae group occurring in the vicinity of Ilha de Marajó is H. curupira, described in the present study.However, the number of lateral line scales (43) reported by Goeldi (1898) does not match with the range registered for H. curupira (34-39).
Alves Francisco because it was originally described from rio Ribeira de Iguape and was missing from earlier ichthyological surveys in the rio São Francisco.The absence of H. intermedius in previous reports of the São Francisco fish fauna is due to the fact that past naturalists failed to recognize two groups of species in that basin based on the orientation of the contralateral dentaries (Lütken, 2001).This resulted in taxonomic confusion and the placement of H. intermedius in the synonym of H. malabaricus.After these two groups had been formally defined by Oyakawa (1990), Hoplias aff.lacerdae (= Hoplias intermedius) began to be included in the ichthyological surveys of the rio São Francisco, but was erroneously regarded as an exotic species introduced from the rio Ribeira de Iguape basin.
Although several karyotypes have been reported for the Hoplias malabaricus group (e.g.Bertollo et al., 1983;Dergam & Bertollo, 1990;Bertollo et al., 2000), only one karyotype has been described for specimens of the Hoplias lacerdae group collected in the upper rio Paraná basin (Bertollo et al., 1978).The diploid number cited by these authors, 2n = 50, is regarded herein as belonging to H. intermedius, as that species occurs in the upper rio Paraná basin.Further karyotype and molecular studies involving Hoplias intermedius from rio São Francisco and rio Doce basins would greatly aid in the knowledge of this species regarding its disjunct distribution.
Hoplias intermedius inhabits main rivers channels and marginal lagoons (Vieira et al., 2005).Juveniles were captured in floodplain lakes (Meschiatti et al., 2000).The species is common in reservoirs (e.g.Cunico & Agostinho, 2006;Silva et al., 2006a) and has economic importance (Alves & Pompeu, 2001;Vieira et al., 2005).Its piscivorous habit (Alvim & Peret, 2004) makes it vulnerable to the bioaccumulation of mercury.In the rio das Velhas, a tributary to the rio São Francisco, its flesh had the highest permitted level of mercury (Alves & Pompeu, 2001).tooth medium sized.Sixth tooth canine and almost as large as anterior most premaxillary canine.Second to fourth, seventh and eighth premaxillary teeth small.Maxilla with single row of approximately 38 relatively small teeth, except for very well developed canine-like fourth tooth.Dentary with anterior external row of teeth and posterior internal row.External series with three anterior small teeth, followed by two well developed canines, with posterior canine larger than anterior canine and then ten conical teeth, slightly smaller than anterior most dentary canine.Internal series beginning at level of last conical tooth of external row and composed of approximately 15 very small teeth.Accessory ectopterygoid and ectopterygoid toothed.Ectopterygoid with series of small conical teeth along its ventrolateral margin and many smaller viliform teeth medially on its ventral surface.Endopterygoid edentulous.
Distal margins of all fins rounded.Total dorsal-fin rays 12-15 (n = 90; ii,10-13; mode: ii,11, n = 66).Dorsal fin located at midbody, its origin at vertical through approximately fourth scale anterior on series along pelvic-fin origin.Longest dorsalfin ray approximately three-quarters of body depth in specimens smaller than 160 mm SL and almost half of body depth in larger specimens.Anal-fin base short.Total analfin rays 9-12 (n = 89; ii,7-10, mode: ii,8, n = 56).Tip of depressed dorsal fin reaching vertical through anal-fin origin in smaller specimens (< 160 mm SL), but falling short of vertical through that point in larger specimens.Total pectoralfin rays 11-15 (n = 89; i,10-14; mode: i,12, n = 35).Pectoral-fin origin located at vertical through central portion of opercle.Tip of pectoral fin separated from pelvic-fin origin by five to nine scales.Pectoral and pelvic fins of similar size, slightly larger than anal fin in specimens larger than 380 mm SL.Pelvic-fin rays i,7 (n = 86).Pelvic-fin origin situated at midbody approximately four scales posterior to vertical through dorsal-fin origin.Tips of pelvic fin separated from vertical through anal-fin origin by five to seven scales.Caudal-fin rays i,15,i (n = 15).
Well developed cycloid scales imbricated along body.Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine.Last vertical series of scales on caudal peduncle forms almost straight line on caudal-fin base in specimens smaller than 160 mm SL, and slightly convex arch on caudal-fin in larger specimens.Anterior margin of scales with small recess and posterior margin rounded.Eight to eleven radii extending from center of scale to its anterior margin and around eighteen radii, some anastomosed, extending from center of scale to its dorsal, posterior and ventral margins.Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body.Lateral line with 43-48 (n = 89, 43 in one specimen; mode: 46, n = 28) perforated scales (Table 2).Lateral-line scales with single laterosensory canal.Longitudinal series of scales between lateral line and dorsal-fin origin 4.5-6.5 (n = 88; mode: 5.5, n = 61).Longitudinal series of scales between lateral line and pelvic-fin origin 4. 5-6.5 (n = 86; mode: 4.5, n = 63).Longitudinal series of scales around caudal peduncle 18-22 (n = 88; mode: 20, n = 73).
Color in alcohol.Ground coloration of head and body dark to light brown, darker dorsally and paler ventrally.Ventral region white to light yellow in most specimens.Single dark midlateral stripe along lateral line stripe more evident in specimens smaller than 100 mm SL.Midlateral stripe crossed by five to seven dark bars, each three to five scales wide.Diagonal bars in many specimens continuing posteroventrally approximately two or three longitudinal series of scales ventral of lateral line, resulting in chevron-like pattern more conspicuous in specimens smaller than 160 mm SL.Dorsal portions of bars more evident than ventral region.Ground coloration of dorsal surface of head, infraorbital region and opercular series dark brown, with dark reticulated pattern on dorsal surface of head in some specimens.Lips with alternating dark and light vertical bands in specimens smaller than 160 mm SL and completely dark in larger specimens.Coloration of infraorbital region similar to dorsal surface of head.Many specimens with one or two dark stripes extending radially and posteriorly from eye across opercular series and third stripe extending posteroventrally from eye across posterior region of maxilla.Ground coloration of opercular series dark brown.Opercular membrane usually lighter than opercle.
All fins light brown (lighter than body) with dark spots on rays and interradial membranes forming pattern of irregular dark stripes.Stripes of dorsal and caudal fins wider than those of anal fin.Stripes less regular in dorsal fin.Ventral surfaces of pectoral and pelvic fins either lighter than or with same pattern as dorsal surface, but with pattern less conspicuous.
Distribution.Known from the type-locality and its vicinity, rio Ribeira de Iguape basin, and from the rio Uruguay basin, including the río Negro in Uruguay (Fig. 3).

Remarks.
Hoplias lacerdae has been regarded as having a wide distribution, occurring in the rio Ribeira de Iguape as well as in rivers of the Amazon, Paraná, São Francisco, Uruguay and other basins.Results presented herein, however, demonstrate that specimens found in the rio Ribeira are morphologically different from those of remaining cited basins with the exception of rio Uruguay.The distribution of Hoplias lacerdae is therefore restricted to rio Ribeira de Iguape and rio Uruguay, being in sympatry with Hoplias australis in the latter basin.
Although samples from the rio Ribeira and rio Uruguay did not differ significantly in the meristic and morphometric features examined in the present study, some geographical disparities should be pointed out.Most specimens from the rio Ribeira have 6.5 and 5.5 scales above and below lateral line, respectively, while the majority of specimens from the rio Uruguay have 5.5 and 4.5 scales above and below lateral line respectively.Specimens from the rio Ribeira tend to have fewer lateral line scales than do specimens from the rio Uruguay (modes: 44 and 46, respectively) and more pectoral-fin rays than do samples from the rio Uruguay (i,13-14 vs. i,10-13, respectively).Nevertheless, these subtle differences must be qualified by the fact that they are not absolute and specimens of H. lacerdae from the rio Ribeira are rare in collections (only ten specimens were available for this study).More specimens from rio Ribeira and the use of cytogenetics and molecular approaches may determine whether these two populations constitute different species.Bertolletti et al. (1990) and Pessano et al. (2005) cited H. lacerdae from the rio Uruguay basin, the former in the area of Garabi Hydroelectric Station and the latter in Arroio Quarai-Chico.These authors, however, did not mention the basis of those identifications, nor did they illustrate their material.Therefore, it is impossible to determine whether they were dealing with Hoplias lacerdae or the new species, H. australis, described herein, both of which occur in the rio Uruguay basin.
A few specimens of Hoplias lacerdae from Ernestina reservoir in the rio Jacuí, a river running into the Atlantic Ocean in Rio Grande do Sul, southern Brazil, were examined.Malabarba (1989: 127) and Carlos Lucena (pers.comm.)mentioned that the species was introduced from rio Uruguay to rio Jacuí system in the 1980s.Native occurrence of Hoplias lacerdae is therefore considered restricted to the rio Uruguay and rio Ribeira de Iguape drainages.Zaniboni Filho et al. (2004) reported some biological features of this species in the rio Uruguay including length, weight, and growth curve.According to them, the species has fractional spawning and an economic importance in local fisheries and aquacultures.
In the rio Ribeira de Iguape, the species is regarded as rare by local fisherman and a two-year survey of its ichthyofauna failed to yield specimens of this species (Oyakawa et al., 2006).The small number of specimens of Hoplias lacerdae from rio Ribeira in ichthyological collections may be additional evidence that this species is uncommon, requiring further studies on its ecology and biology and special attention to its conservation status.
demonstrated that populations of H. malabaricus from the upper rio Doce, upper rio Paraná, and upper rio Paraíba do Sul are genetically close, indicating a possible common origin or recent exchanges between these basins.Vieira et al. (2005) also suggested a common ancestry between the rios São Francisco and Doce based on their ichthyofauna.

Table 1 .
Morphometric data of Hoplias australis.Standard length in mm; values 1-14 are percents of standard length and values 15-22 are percents of head length.n = number of examined specimens.
First premaxillary tooth large canine, second, seventh and ninth teeth medium sized.Eighth tooth canine and almost as large as anterior most premaxillary canine in large specimens (ca.220 mm SL).Third to sixth premaxillary teeth small.Maxilla with single row of approximately 30

Table 2 .
Frequency distribution of total number of lateral line scales in species of the Hoplias lacerdae group.

Table 3 .
Frequency distribution of total number of pores of cephalic lateral system along the ventral surface of the dentary in species of the Hoplias lacerdae group.

Hoplias brasiliensis (Spix, 1829) Fig. 4
described Macrodon auritus based on one specimen collected in Montevideo, Uruguay, from rio Uruguay basin.It is not clear, however, from the original description whether the species belongs to the Hoplias lacerdae group or to either of the two taxa of this group documented from the rio Uruguay in this study.Unfortunately, the type specimen of M. auritus has not been located in MNHN, contrary to the other type specimens of the Erythrinidae described inValenciennes (1846) [P.Pruvost,  pers.comm.].Macrodon auritus is therefore considered a nomen dubium(ICZN, 1999).Two species of Hoplias lacerdae group, H. australis and H. lacerdae, occur in sympatry and syntopy in the rio Uruguay basin, and were collected together at some localities.Hoplias lacerdae also occurs in the rio Ribeira de Iguape (see below), and H. australis is, thus, the only Hoplias species apparently endemic to the rio Uruguay basin.Judging from the amount of material in museum collections, H. australis is much less common in the rio Uruguay than H. lacerdae.Morphometric data presented in Table4.Body cylindrical, deeper than wide.Greatest body depth at vertical through fifth scale anterior to dorsal-fin origin in specimens smaller than 35 mm SL, closer to dorsal-fin origin in larger specimens.Anterior profile of head angular in lateral view, more rounded in specimens smaller than 100 mm SL.Dorsal profile of head varying from slightly convex in specimens smaller than 100 mm SL to almost straight in specimens larger than 130 mm SL.Dorsal margin of orbit located at horizontal to through dorsal profile of head in specimens smaller than 100 mm SL but not reaching dorsal profile of head in specimens larger than 130 mm SL.Dorsal profile of body slightly convex from vertical through first series of scale of body to dorsal-fin origin in specimens smaller than 130 mm SL and almost straight in larger specimens (ca. Fig. 3. Map of South America showing geographic distribution of species of the Hoplias lacerdae group based on material examined in this study.Some symbols may represent more than one lot.Numbers indicate type localities of (1) Hoplias australis (squares); (2) H. brasiliensis (losanges); (3) H. curupira (triangles); (4) H. intermedius (dots); and (5) H. lacerdae (inverted triangles).

Table 4 .
Morphometric data of Hoplias brasiliensis.Standard length in mm; values 1-14 are percents of standard length and values 15-22 are percents of head length.n = number of examined specimens.
aff. lacerdae:-Lima et al., 2005: 155[species list, occurrence in the rio Tiquié, tributary of upper rio Negro, biological, ecological and ethnoichthyological notes].Hoplias curupira differs from the other species of H. lacerdae group in always having four pores of the laterosensory canal along the ventral surface of the dentary that become gradually subdivided into four patches of multiple pores in specimens larger than 60 mm SL; a dark brown ground Oct 1983; MNRJ 30395, 4, 136.1-168.7mmSL,samelocalityanddate;MZUSP33481, 1, 250.0 mm SL, same locality and collector,Jun-Jul 1983; MZUSP 22283, 4, 94.9-225.7mmSL,IgarapéPacuíonkm97 of Belém-Brasília road, 15 Aug -20 Oct 1959, Expedição Departamento de Zoologia.Material examined.BRAZIL.Amazonas State.Negro basin: MZUSP34011, 2, 216.4-220.8mmSL;MZUSP34013, 1, 271.5Diagnosis.coloration of head and body; by having fewer lateral line scales (34-39 vs. 38-48 in remaining species of H. lacerdae group) and a wider head, with larger ranges of relative snout width and interorbital width (13.1-27.2% and 16.0-35.5%respectively,vs.12.6-22.9%and14.9-30.1% in the remaining species of H. lacerdae group) (Figs.6-7).In addition, an anterior profile of head that is rounded in lateral view distinguished H. curupira from H. brasiliensis and H. intermedius, which have the anterior profile of head angular.Description.Morphometric data presented in Table5.Body cylindrical, deeper than wide.Greatest body depth at vertical through third scale anterior to dorsal-fin origin in specimens smaller than 85 mm SL, closer to dorsal-fin origin in larger specimens.Anterior profile of head rounded in lateral view, more angular in specimens smaller than 85 mm SL.Dorsal

Table 5 .
Morphometric data of Hoplias curupira.Standard length in mm; values 1-14 are percents of standard length and values 15-22 are percents of head length.n = number of examined specimens.

Table 6
. Body cylindrical, deeper than wide.Greatest body depth at vertical through fifth scale anterior to dorsal-fin origin in specimens

Table 6 .
Morphometric data of Hoplias intermedius.Standard length in mm; values 1-14 are percents of standard length and values 15-22 are percents of head length.n = number of examined specimens.