Revision of the Hyphessobrycon heterorhabdus-group ( Teleostei : Characiformes : Characidae ) , with description of two new species from Venezuela

Currently about 110 nominal species are included in the genus Hyphessobrycon DURBIN, 1908 (GARCÍA-ALZATE & ROMÁN-VALENCIA, 2008). These usually small to tiny fi shes are widely distributed from southern Mexico to the Río de la Plata in Argentina. The genus was proposed by DURBIN (1908) using Hemigrammus compressus MEEK, 1904, the northern most representative of the genus, as type and the combination of the following characters as a diagnosis: lateral line incomplete, adipose fi n present, maxilla with few or no teeth, third infraorbital not in contact with preopercle, two series of premaxillary teeth with fi ve teeth in its inner row and caudal fi n naked. At present this diagnosis is obsolete and the genus requires re-description. No phylogenetic defi nition of the genus exists, so the inclusion of species using the combination of characteristics is without practical application today. Some authors have proposed the recognition of species groups based on shared color or pigmentation patterns (GÉRY, 1978; WEITZMAN & PALMER, 1997). The hetero rhbadus-group is defi ned by the presence of a dark stripe along the mid-axis of the body. WEITZRevision of the Hyphessobrycon heterorhabdus-group (Teleostei: Characiformes: Characidae), with description of two new species from Venezuela


Introduction
Currently about 110 nominal species are included in the genus Hyphessobrycon DURBIN, 1908 (GARCÍA-AL-ZATE & ROMÁN-VALENCIA, 2008).These usually small to tiny fi shes are widely distributed from southern Mexico to the Río de la Plata in Argentina.The genus was proposed by DURBIN (1908) using Hemigrammus compressus MEEK, 1904, the northern most representative of the genus, as type and the combination of the following characters as a diagnosis: lateral line incom-plete, adipose fi n present, maxilla with few or no teeth, third infraorbital not in contact with preopercle, two series of premaxillary teeth with fi ve teeth in its inner row and caudal fi n naked.At present this diagnosis is obsolete and the genus requires re-description.

Hyphessobrycon diancistrus
Description.Morphometric and meristic data presented in Table 1.Body long, not deep, fusiform.Dorsal profi le of head curved from snout to supraoccipital, partially concave from this point to dorsal-fi n origin, curved from base of last dorsal ray to base of adipose thence straight to base of caudal.Ventral profi le of head and body convex from snout to anal-fi n base.Head short but snout elongate, fi tting twice in HL; jaws equal; mouth terminal: lips soft and fl exible, covering externally outer row of premaxilla teeth; ventral portion of upper jaw straight; posterior limit of maxilla not reaching anterior margin of orbit.
Osteological characters.Premaxilla with two rows of teeth and short, rounded lateral process that inserts between nasal and mesethmoid.Three teeth of outer row tricuspid, and arranged in a line (fi g. 4).Internal row with six heptacuspid teeth that diminish gradually in size (fi g. 5).Maxilla long, anterior ventral margin convex, toothless (fi g. 4), posterior ventral margin straight, not in contact with infraorbitals.Metapterygoids with upper border wide and with a laminar prolongation at the upper dorsal edge, and with two foramina in the posterior region.Ectopterygoids reduced, not in contact with the quadrate, and with the upper margin concave (fi g. 6).
Six infraorbitals present, the fi rst fusiform and laterally concave, the third, the longest of the series, with its ventral margin concave, the shape of the fi fth infraorbital, the widest of the series, suggests fusion with the sixth.Antorbital anteriorly semi convex and with a wide ventral section.Supraorbital absent.Mesethmoid longer than wide, its anterior margin inserted over the posterior surface of the premaxilla.
Rhinosphenoid bony, united to orbitosphenoides by a band of cartilage, united ventrally with dorsal margin of parasphenoids.Orbitosphenoid bony, elongated anteriorly, with a small rounded apophasis on the antero-ventral section, a small rounded foramen is present near the junction with the pterosphenoids.Parasphenoid united to ventral surface of vomer by cartilage; extreme posterior tip of parasphenoid in contact with the basioccipital and united to prootic by a band of cartilage.Nasal bones present.
22 total gill-rakers; 15 in the upper limb and seven in the lower limb.Dorsal-fi n margin straight.Proximal pterygiophores of dorsal-fi n rays inserted between neural spines 7 to 17; anal fi n with 16 proximal pterygiophores the fi rst two inserted between hemal spines 13 and 14, and the fi fth to seventh inserted between hemal spines 15 and 16.Five thin elongate supraneurals and 14-15 epipleurals.branched ray of anal fi n; 11 or 12 spines present on second to fi fth branched rays, and 6-8 pairs of spines on pelvic-fi n rays.

Comments:
We noted small differences in the pigmentation pattern of the caudal fi n among paratypes.Osteological characters.Premaxilla with long and pointed lateral process, inserted between nasal and lateral margin of mesethmoid.Teeth in two rows, outer with four tricuspid teeth, arranged in a irregular line.
Inner row with fi ve pentacuspid teeth that diminish gradually in size (fi g. 5).Maxilla short, undulated anteriorly, curved posterior and with one heptacuspid tooth.Posterior tip of maxilla in contact with anterior margin of second infraorbital (fi g. 4).Dentary with posterior dorsal and ventral borders rounded, the postero-dorsal margin convex; with 8-9 teeth on its anterodorsal margin; four large pentacuspid teeth anteriorly, followed by 4-5 tricuspids that diminish in laterally.
Metapterygoid with upper border wide and with two laminar prolongations on dorsal margin, a foramen in the posterior region, and a band of cartilage on the anterior side anterior that unites it with the quadrate and ventro-posteriorly with the hyomandibular.Hyomandibular with anterior margin concave.Ectopterygoids short and wide, in contact with quadrate, with band of cartilage along entire posterior margin.Mesopterygoid reduced with convex upper edge (fi g. 6).Six infraorbitals present, the fi rst fusiform, anterior and posteriorly concave, the second with four small foramina arranged in a line in the antero-medial region, the third is the longest but it is in contact with the sensory canal of the preopercle.Antorbital convex anteriorly, the ventral part wide.Supraorbital absent.The mesethmoid has undulated lateral edges and is inserted between the anterior surfaces of the premaxilla in dorsal view.Supraoccipital process short.Elongate nasal bone present.
Rhinosphenoid cartilaginous.Orbitosphenoids bony, elongated anteriorly and with a small rounded apophasis on ventro-anterior part, and a rounded foramen on the ventral edge.Parasphenoids long and not divided, united to ventral surface of vomer by means of cartilage; posterior tip of parasphenoid in contact with basioccipital and with prootic by band of cartilage.
Basihyal bony.Pharyngeal plate short.16 total gillrakers, 11 in the upper limb and fi ve in the lower limb.Margin of dorsal fi n oblique, small vestigial, sharp projecting ray present just anterior to dorsal fi n.Proximal pterygiophores of dorsal fi n rays inserted between neural spines 9 to 16; proximal pterygiophores of the anal fi n 18, the fi rst two inserted between hemal spines 12 and 13.Five thin, elongate supraneurals, with cartilage on upper tips.
Pectoral girdle with a sharp dorsal process above the cleithrum, which is elongate.Postemporal with upper tip pointed and with a bony pointed apophasis on its antero-ventral margin.Four proximal radials.Pelvic fi n short, its tip not reaching anal-fi n origin.Caudal peduncle robust, caudal fi n bifurcate with short pointed lobes.Principal caudal rays 1/18/1 with 8/8 procurrents.Scales cycloid.Caudal fi n scaleless.Anal fi n with sheath of two rows of accessory scales on base from last two simple rays continuing on fi rst 11 branched rays.32-33 vertebrae.
Sexual dimorphism: Males with six or seven spines on third unbranched anal-fi n ray, four to nine hooks on fi rst nine branched anal-fi n rays and seven or eight pairs of spines on pelvic-fi n rays.
Color in alcohol: Body light yellow, dorsally brown.Dorsal area of head dark.Lateral part of body with strong dark band, continuing from posterior margin of opercle onto central caudal-fi n rays.Posterior portion of scales dark.Dorsal and anal fi ns with small dark dots between rays, pectoral, pelvic and adipose fi ns hyaline.
Comments.In his description, SCHULTZ (1944) gave no diagnosis, and reported 13 branched pectoral-fi n rays and a range of 15-21 branched anal-fi n rays; in the specimens examined we count only 11-12 branched pectoral-fi n rays, and iii 19-21 anal-fi n rays (table 2).No signifi cant differences were detected with the principal component analysis.This species is very similar to H. fernandezi, differing in the number of teeth in the inner premaxilla row (fi ve vs. six), in the number of cusps on the maxillary teeth (seven vs. three), by the number of teeth on the dentary (8-9 vs. 10-11), by the number of vertebra (32 or 33 vs. 30), in the number of pored scales in the lateral line (9 or 10 vs. 11 or 12), in the number of dorsal-fi n rays (ii, 9 vs. iii, 8), in the number of unbranched anal-fi n rays (iii vs. iv-v) and by the distance from the snout to the pectoral fi n insertion .Neotype.MBUCV-V 34105; (1) Venezuela, Quebrada Cupa, fi nca de Víctor Atria, Cerca a Aroa en la vía a Duaca, 10º 29' 50''N, 68º 52 ' 20''W, Yaracuy, 7 Jul. 1985.Diagnosis.This species is distinguished from its congeners in Venezuela by having the combination of four or fi ve unbranched anal-fi n rays (vs.iii-iv), three unbranched and 8 branched dorsal-fi n rays (vs.two unbranched and nine branched rays, except in H. notidanos with iii, 8), six teeth in the inner premaxillary tooth row (vs.5), 13 branched rays in pectoral fi ns (vs.10-11), the absence of the rhinosphenoid (vs.presence) and by having the dark lateral band that fades out at a point beneath the adipose fi n and then starts up again as a vertical caudal peduncle blotch that covers the bases of the middle caudal-fi n rays (vs.dark lateral band continuous to middle caudal-fi n rays).Description.Morphometric and meristic data presented in Table 2. Body short and deep, robust.Dorsal profi le of head and body straight from snout to supraoccipital, oblique from this point to dorsal-fi n origin, slightly concave from last dorsal-fi n ray to base of caudal fi n.Ventral profi le of head and body convex from snout to base of anal fi n.Caudal peduncle not deep.Head short, snout long.Jaws equal; mouth terminal; lips soft and fl exible covering externally the outer row of premaxillary teeth.Ventral margin of upper jaw straight; posterior limit of maxilla not reaching anterior margin of second infraorbital.

Hyphessobrycon fernandezi FERNÁNDEZ-YÉPEZ, 1972
Osteological characters.Premaxilla with short and rounded lateral process; inserted over lateral margin of mesethmoid.Two rows of premaxillary teeth, the outer row with four tricuspid teeth arranged in a irregular line.Internal row with six teeth; fi rst fi ve pentacuspid and the last conical (fi g. 4).Teeth diminishing gradually in size medially (fi g. 5).Maxilla short, convex anteriorly with one tricuspid tooth, posterior margin straight, posterior tip not in contact with infraorbitals.Dentary with dorsal margin convex and ventral margin oblique, the posterodorsal margin rounded, with 10-11 teeth located on its anterodorsal edge.Four large pentacuspid teeth anteriorly with the second projecting outward.Large teeth followed laterally by one tricuspid tooth, and then 5-6 conic teeth that diminish in size laterally.Meckel's cartilage extends along entire medial surface.A small rounded foramen present in antero-medial region.Metapterygoids with wide upper border and with laminar prolongation on anterodorsal margin and a pointed, bony apophasis on the postero-dorsal edge that unites with the ventral margin of hyomandibular.A small foramen is present in posterior region.Articulations among quadrate, mesopterygoid and hyomandibular without cartilage, there is no fusion.Ectopterogoid in contact with quadrate.Mesopterygoid large with undulated upper margin, equal length to ectopterygoid.Metapterogoid has a syndesmotic articulation with mesopterigoid (fi g. 6).
Six infraorbitals present, the fi rst anteriorly convex and posteriorly straight, the third is the longest and its ventral margin not in contact with preopercle.Antorbital anteriorly convex, upper part pointed.Supraorbital absent.Mesethmoid wider in middle region than at tips, inserted between the anterior surfaces of the premaxillaries in dorsal view.Supraoccipital process long.Nasal bone reduced.
Rhinosphenoid cartilaginous.Orbitosphenoid bony, elongated anteriorly, with a thick rounded apo phasis on ventro-anterior portion.Parasphenoid long, united to ventral surface of vomer by means of cartil age.Basihyal cartilaginous.Pharyngeal plate short and curved.19 total gill-rakers, 13 in the upper limb and six in the lower limb.Margin of dorsal fi n oblique, dor sal fi n with small bony prolongation similar to anterior vestigial ray.Proximal dorsal-fi n pterygiophores inserted between neural spines 6 to 16; proximal analfi n pterygio phores numbering 20, the fi rst four inserted bet ween hemal spines 12 and 13.Five long supraneurals, thick in upper region and with cartilage at tip.
Pectoral girdle with a sharp dorsal process over cleithrum.Postemporal with sharp upper tip, and with a bony apophasis at antero-ventral margin.Extrascapular fusiform.Three proximal radials.Pelvic fi n short, its tip not reaching origin of anal fi n.Caudal fi n bifurcate with short lobes.Principal caudal rays 1/18/1 with 8/8 procurrents.Scales cycloid.Caudal fi n not scaled.Anal fi n with sheath of 5-6 accessory scales between last three simple rays and along bases of fi rst six branched rays.30 vertebrae.

Sexual dimorphism.
Males with 8-10 spines on fourth unbranched anal-fi n ray, 8-12 hooks on fi rst seven branched anal-fi n rays and 6-8 pairs of spines on pelvic-fi n rays.Comments.The validity of this species has been little discussed, unlike other species described by FER-ANÁNDEZ-YÉPEZ (1972): Bryconops melanurus and B. giacopinii (CHERNOFF et al., 1994).The identity of H. fernandezi was dubious because FERANÁNDEZ-YÉPEZ presented no formal diagnosis, few distinguishing characteristics, and an illustration that showed no diagnostic features.For example the teeth described are typical of any tetragonopterine: two intermaxillary rows and one on the dentary.We assume that by intermaxillary teeth FERANÁNDEZ-YÉPEZ meant premaxillary teeth.He also reported fi ve teeth in the inner intermaxillary row, but we fi nd six; three unbranched anal-fi n rays and 18 to 26 branched rays, and 16 (11-17) pored scales in the lateral line, values that all differ from those we found (Table 2).
Since the type material used by FERANÁNDEZ-YÉPEZ (1972) was lost, we designate a neotype from the original type locality, in the context of this re-description.
Diagnosis.Hyphessobrycon paucilepis is distinguished from its Venezuelan congeners by having: three unbranched and eight branched rays in the dorsal fi n (vs.two unbranched and nine branched rays except in H. notidanos, H. oritoensis and H. fernandezi), a short maxilla (vs.long maxilla), a maxilla with one pentacuspid tooth (vs.maxillary teeth tricuspid), eight teeth on the dentary (vs.10-19, except in H. notidanus and H. proteus), a premaxilla with 2-3 teeth in the outer row (vs.4), 28-29 lateral scales (vs.30-34), 9 predorsal scales (vs.12-14), an absence of sexual dimorphism (vs.presence), a dark lateral band that extends from the upper rear margin of the opercle to the caudal peduncle and continues as a rhomboidal peduncular blotch onto the middle caudal fi n rays (vs.lateral band lacking rhomboidal caudal peduncle blotch).Description.Morphometric and meristic data given in Table 3. Body long and deep.Dorsal profi le of head oblique, slightly curved from snout to supraoccipital, body oblique from this point to dorsal-fi n origin, straight from last dorsal-fi n ray to base of adipose fi n.Ventral profi le of head and body convex from snout to base of anal fi n.Head short, snout long; jaws equal; mouth subterminal; lips soft and fl exible, covering externally the outer row of premaxillary teeth; ventral part of upper jaw straight; posterior limit of maxilla not reaching anterior margin of second infraorbital..49-28.53 (27.16) 30.42 24.14-31.30(27.31)Total length 37.79 30.40-38.56 (35.32) 39.2 30.77-41.78(35.10)Percent Standard Length: Osteological characters.Premaxillary with long, rounded lateral process, overlaying mesethmoid anteriorly, and with two rows of teeth.Outer with three tricuspid teeth arranged in a irregular line.Inner row with fi ve pentacuspid teeth that diminish in size gradually.Maxilla long, ventral margin anteriorly convex with one pentacuspid tooth, posteriorly straight, posterior tip in contact with the fi rst infraorbital (fi g. 10).Dentary with dorsal edge curved, ventrally undulated, posterodorsal margin convex; 7-8 teeth on anterodorsal margin; four large anterior teeth pentacuspid, second projecting outward in all specimens examined, followed by one tricuspid tooth and 1-2 conic teeth that diminish in size medially.Metapterygoids with upper border narrow and with a large laminar prolongation on the dorso-anterior edge.Ectopterygoids long and narrow, not in contact with the quadrate, and with bands of cartilage on their posterior margins.Mesopterygoid large with convex upper edge (fi g. 11).
Six infraorbitals present, the third is the longest and widest of the series, and has its ventral margin in contact with the sensory canal of preopercle, the ventral anterior margin reaches the interopercle.Antorbital anteriorly straight and posteriorly concave, upper section rounded.Supraorbital absent.Lateral ethmoid a long, concave bone that is not united to frontal and that extends to unite anteriorly with the vomer.The mesethmoid is wide and short.Epiphyseal bar extremely narrow.Supraoccipital process short.Nasal bone reduced, tubular.
Rhinosphenoid cartilaginous.Bony orbitosphenoid elongated anteriorly, with a wide straight apophasis at ventro-anterior edge; a rounded foramen present at its union with the pterosphenoid.Parasphenoid elongate, united with ventral edge of vomer by a band of cartilage, a band of cartilage present along posterior tip contacting basioccipital and prootic.
22 total gill-rakers, 14 in the upper limb and eight in the lower limb.Dorsal fi n margin oblique.A short bony element present just anterior to fi rst ray, similar to a vestigial ray.Proximal dorsal-fi n pterygiophores inserted between neural spines 9 to 16; 22 proximal anal-fi n pterygiophores the fi rst three inserted between hemal spines 12 and 13.Four elongate supraneurals, thicker near their upper tips, inserted between neural spines 5 to 8. Pectoral girdle with a pointed dorsal process above cleithrum.Postemporal with upper tip rounded, extrascapular elongate.Four proximal radials.Pelvic fi n short, its tip not reaching anal-fi n origin.
Pelvic girdle elongates with convex dorsal margin and straight ventral margin; situated parallel to central axis of body, pointed anteriorly.Caudal fi n bifurcate with short lobes.Principal caudal rays 1/17/1 with 10/10 procurrents.Scales cycloid.Caudal fi n not scaled.Anal fi n with a series of six scales between the last two simple and fi rst eight branched anal-fi n rays.32 vertebrae.No sexual dimorphism observed.
Color in alcohol.Body yellow, dorsal region light brown.Snout and dorsal area of head dark.Infraorbital series and opercle silvery.Sides of body with dark lateral band extending from behind upper edge of opercle to caudal peduncle, then continuing as dark rhomboidal peduncular blotch onto middle caudal-fi n rays.Posterior portions of scales dark.Anal and dorsal fi ns with small dark dots on interradial membranes.Pectoral, pelvic and adipose fi ns hyaline.
Geographic distribution.Known only from type locality and small adjacent drainages in Lara state, northern Venezuela (fi g. 13).
Etymology.The name is from Greek words pauci = few and lepis = scales, referring to the low lateral and predorsal scale counts of this species.
Diagnosis.Hyphessobrycon tuyensis differs from congeners in having four teeth in the inner premaxilla row (vs.fi ve); seven pored scales in lateral line (vs.8-16, except in H. compressus with 7-9); six dentary teeth (vs. 7-19); two foramina in maxilla (vs.none); mouth subterminal (vs.terminal); a long bony laminar prolongation on postcleithrum 3 that is ¾ of the length of that bone (vs.bony prolongation small); and a continuous dark lateral band from posterior edge of opercle through central caudal-fi n rays (except in H. sovichthys).
Description.Morphometric and meristic data given in Table 3. Body long, not deep, fusiform.Dorsal profi le of head and body oblique from snout to dorsalfi n origin; straight between base of last dorsal-fi n ray and caudal-fi n base.Ventral profi le of head and body convex from snout to anal-fi n base.Head short; snout long; jaws equal; mouth subterminal; lips soft and fl exible, not covering the outer row of premaxilla teeth.Ventral part of mandible straight; posterior limit of maxilla reaching anterior margin of second infraorbital.
Osteological characters.Premaxilla with lateral process short and pointed, inserted over lateral margin of mesethmoid, and with two rows of teeth, the outer row with four tricuspid teeth arranged in a irregular line; the inner with four pentacuspid teeth that diminish gradually in size from inner to outer tooth (fi g. 10).Maxilla long, anteriorly convex and undulated, with one lobulate tooth, posteriorly undulated, with two rounded foramina in antero-medial section.A canal is present from the upper foramen and the antero-superior region of the maxilla above the tooth (fi g. 10).Dentary with dorsal margin convex and ventrally oblique, upper posterior margin undulated, with 5-6 teeth on upper anterior edge; four large front heptacuspid teeth followed two conic teeth that diminish in size medially.Meckel's cartilage extends along entire medial surface.Metapterygoids with upper border wide and with three laminar prolongations on dorsal margin, and a sharp bony apophysis on ventro-posterior mar-gin that projects towards symplectic, two foramina present in posterior section.Ectopterygoids long and narrow in contact with quadrate, no bands of cartilage present.Mesopterygoids large and with upper margin undulated, same size as ectopterygoids.Symplectic and cuadrate above the preopercle (fi g. 11).
Six infraorbitals present, the fi rst inserted underneath second infraorbital and with rounded apophysis on anterior margin, third infraorbital the longest and widest of series, its ventral margin in contact with the sensory canal of preopercle.Antorbital anteriorly convex, posteriorly concave, upper region rounded, in contact with maxilla and fi rst infraorbital.Mesethmoid wider posteriorly.Supraoccipital process long.Nasal bone reduced.In dorsal view the cranium shows a compression of the bones, making the mouth subterminal.Supraorbital absent.
Rhinosphenoid absent.Orbitosphenoid with small foramen in medial region.Parasphenoid elongate and not divided, united along ventral surface with vomer by cartilage; without cartilage at posterior tip.20 gill rakers on fi rst arch, 12 in the upper limb and eight in the lower limb.Border of dorsal fi n oblique.With a small bony element similar to a vestigial ray present just anterior to fi rst dorsal-fi n ray.Proximal pterygiophores of dorsal fi n inserted between neural spines 9 to 16; 22 proximal anal-fi n pterygiophores, the fi rst three inserted between hemal spines 12 and 13.Four elongate supraneurals, thicker in upper region.
Postemporal with upper tip sharp, extrascapular with anterior region wide.Third postcleithral long and curved with a laminar bony undulated process on posterior margin that is ¾ of the length of third postcleithral (fi g. 12).Five proximal radials.Caudal fi n bifurcate with long pointed lobes.Principal caudal rays 1/17/1 and 8/8 procurrents.Scales cycloid.Caudal without scales.Anal fi n with sheath of two series of accessory scales fi ve to six scales in fi rst row and three in second, between the last three simple rays and the fi rst four branched.32 vertebrae.& GIRARD) and thus are not useful to refl ect phylogenetic relationships (CARVALHO et al., 2008).
One objective of this study, besides recognizing and differentiating the species in the H. heterorhabdus group, was to search for novel characters that may be synapomorphies for groups of Hyphessobrycon species.Among potentially useful characters we found a common, and somewhat unusual dorsal-fi n ray count of (iii, 8)  The diffi culties that arise when trying to distinguish the numerous Hyphessobrycon species are many.Primary among them is the poor description of the type species and the numerous descriptions of new species based on ambiguous characters that overlap with others, many based only on color patterns, as is the case for Hyphessobrycon georgetti GÉRY, 1961;H. auca ALMIRÓN et al., 2004;H. nigricinctus ZARSKE & GÉRY, 2004;H. borealis ZARSKE et al., 2006;H. isiri ALMIRÓN et al., 2006 to name but a few.Also, the use of combinations of characters makes it diffi cult to diagnose the species and to compare specifi c characters used to defi ne the species.
It is generally accepted that Hyphessobrycon is not monophyletic, but there is no hard evidence to support this assertion (LIMA & COSTA, 2001;LUCENA, 2003;ZARSKE & GÉRY, 2004;BERTACO & MALABARBA, 2005;CARVALHO et al., 2008).Constructing a phylogeny is a daunting task because of the very large number of species in the genus.The type species Hyphessobrycon compressus, is from Mexico, the northernmost limit of the range of the genus and so far there is no evidence supporting a relationship between it with the other species Central America nor those from north of the Andes, nor the many trans-Andean species (WEITZMAN & PALMER, 1997: 3) And so, a detailed comparison of    MALABARBA & WEITZMAN (2003) separated a large group of characids previously listed as incertae sedis within Characidae: Astyanax, Hemigrammus, Hyphessobrycon, among others, using the presence of bony hooks on the fi ns and separated them from species of Clade A (Bryconamericus EIGENMANN, Hemibrycon GÜNTHER, Creagrutus GÜNTHER, among others) by several synapomorphies: principally the presence of four teeth in the inner row of the premaxillary.This hypothesis is not very satisfactory, because those characters are too variable and thus fail to uniquely defi ne the group.As an example Hyphessobrycon paucilepis lacks bony hooks on the fi ns and H. tuyensis has four teeth in the inner premaxillary row (fi g. 12).
The preliminary relationships and differences detected here between cis-and trans-Andean species of Hyphessobrycon as well as their current geographical distributions, are consistent with a vicariant event caused by the fi nal uplift of the Mérida Cordillera of the Andes about 8 years ago, and the subsequent change in the course of the river Orinoco to overfl ow the El Baúl arch and eventually reach its current delta, a pattern already noted in several other fi shes (HOORN et al. 1995;DÍAZ DE GAMERO, 1996;AL-BERT et al., 2006).

Tab. 3 .
Morphological and meristic data for H. paucilepis sp.n. and H. tuyensis sp.n.Standard and total length in mm.Mean in parentheses.
Cleithrum elongate, its posterior border rounded, located under ventral edge of opercle.Postemporal with upper tip sharp, extrascapular fusiform.Three proximal radials.Pelvic fi n short, its tip not reaching anal-fi n origin.Elongate pelvic bone situated parallel to central axis of body.Caudal fi n bifurcate with long pointed lobes, Principal caudal rays 1/17/1 with 8/8 procurrents.Scales cycloid.Caudal and anal fi ns without scales.35-36 vertebrae.Morphological and meristic data for H. diancistrus.Standard and total length in mm.Mean in parentheses.