A new species of Hemibrycon ( Characiformes : Characidae ) , a freshwater fish from the Sierra Nevada of Santa Marta , Caribbean drainage , Colombia

Hemibrycon is a group of freshwater characid fish species first recognized by Günther (1864) as a subgenus of Tetragonopterus, and now included in the subfamily Stevardiinae. There are 21 species recorded from the rivers of Colombia, but only one species, H. santamartae, has been reported previously in drainages of the Sierra Nevada de Santa Marta. Hemibrycon sierraensis n. sp. is described from the Río Gaira, Caribbean coastal drainage. It is distinguished from all congeners by having in life a bright red adipose fin (vs. hyaline or transparent) that turns dark brown in specimens preserved in alcohol. It differs from Hemibrycon beni, H. boquiae, H. brevispini, H. colombianus, H. mikrostiktos, H. metae, H. microformaa, H. palomae and H. rafaelense in having a vertically elongate humeral spot that extends 3-4 longitudinal scale series below the lateral line. It differs from H. divisorensis, H. pautensis and H. santamartae by having the last dorsal-fin ray unbranched; and from H. pautensis by the number of scale series between the lateral line and the pelvic-fin insertions. It differs from H. divisorensis in the number of unbranched anal-fin rays, and the number of teeth on the dentary and maxilla. It differs from H. santamartae in the number of supraneurals, caudal peduncle depth, head length and orbital diameter.

The genus Hemibrycon is a group of freshwater characid fish species first recognized by Günther (1864) as a subgenus of Tetragonopterus.Subsequently the subgenus was defined by Eigenmann (1927) as a new genus of Characidae and species were added and subtracted by several authors (Géry, 1962;Bertaco, Malabarba, included in that analysis.Javonillo, Malabarba, Weitzman & Burns (2010) used DNA sequencing techniques and found evidence for the monophyly of the group.
Fishes of the genus Hemibrycon are typically found in clear freshwater habitats in rivers of the Pacific watersheds in Panama, coastal Caribbean drainages, Lake Maracaibo and Orinoco River basins in Venezuela, streams of Trinidad and Tobago, coastal basins of French Guiana and Suriname, coastal Caribbean and Pacific drainages, Catatumbo, Andes and Orinoco drainages in Colombia and upper Amazon River drainages of Bolivia, Peru and Ecuador (Bertaco et al., 2007;Bertaco & Malabarba, 2010;Román-Valencia et al., 2013).Today there are 36 species reported in the genus (Eschmeyer & Fricke, 2013).Of these, 21 species are distributed in the rivers of Colombia, but only one species, H. santamartae, has been reported previously in drainages of the Sierra Nevada de Santa Marta.
This description of a new species of Hemibrycon from the La Sierra Nevada de Santa Marta in Colombia is a result of an ongoing revision (C.G-A and collaborators) of the genus, and is further proof of the as yet undocumented biodiversity of the genus by Central and South America.

MATERIAL AND METHODS
Fishes were captured using seines and were preserved with 10% formalin and later stored in 70% ethanol.Measurements and counts follow Román-Valencia, García-Alzate, Ruiz-C & Taphorn (2010).Measurements were made with digital calipers to 0.01mm precision and are expressed as percentages of standard (SL) and head length (HL).In count ranges, values for the holotype are indicated with an asterisk (*).Counts and measurements were taken on the left side of specimens when possible.Osteological observations were made on cleared and stained specimens (C&S) prepared according to Taylor & Van Dyke (1985) and Song & Parenti (1995).Bone nomenclature follows Weitzman (1962), Vari (1995), and Ruiz-C. & Román-Valencia (2006).Type specimens are deposited in the University of Atlántico Caribbean Region, Dept.Biology, Museum Collection, Barranquilla, Colombia (UARC-IC), Collection of Fishes of Auburn University Natural History Museum, Auburn, Alabama (AUM) and the Ichthyology Laboratory at the Universidad del Quindío, Armenia, Colombia (IUQ).In the lists of paratypes, the number of individuals is given in parentheses immediately after the catalog number.Institutional acronyms follow Sabaj-Perez (2010).
We performed a canonical discriminate analysis on the covariance matrix of morphometric characters with the software program R version 2.15.3 (available free at the website http://cran.r-project.org/bin/windows/base/).The Burnaby method to eliminate the influence of overall size, with the Past program, version 3.0 for Windows.

Hemibrycon
Diagnosis.Hemibrycon sierraensis n. sp. is distinguished from all other species of the genus by having an iridescent red adipose fin in life (vs.hyaline or transparent in life, except H. divisorensis that has a reddish adipose fin) and by having a dark brown adipose fin in alcohol (vs.hyaline or transparent in alcohol).It differs from H. divisorensis, H. pautensis and H. santamartae in having the last dorsal-fin ray unbranched.It further differs from H. beni, H. boquiae, H. brevispini, H. colombianus, H. mikrostiktos, H. microformaa, H. metae, H. palomae and H. rafaelense in having a vertically elongate humeral spot that extends three to four scale rows below the lateral line series (vs.humeral spot roughly circular not extending ventrally three to four scales rows below lateral line series, or with inconspicuous, diffuse vertical extensions).It differs from H. pautensis by the number of scale series between the lateral line and the pelvic-fin insertions (four-five vs. six-seven).It differs from H. divisorensis in the number of unbranched anal-fin rays (iii vs. iv), number of dentary teeth (ten vs. 13-16) and the number of maxillary teeth (six-seven vs. ten-13).In addition to the above characters, we found the following differences that distinguish this new species from those that occur in the same basin (and in allopatry with H. santamartae): fewer supraneurals (six vs. eight), greater caudal peduncle depth (16.5-17.7 vs. 8.7-15.6%SL), longer head length (25.0-29.6 vs.18.4-25.2%SL) and smaller orbital diameter (23.9-34.8 vs. 33.1-45.7%SL).
Description.Morphometric data are in Table 1.Body slender and elongate (mean maximum body depth 31.4% SL).Area between orbits slightly convex.Dorsal profile of head straight to supraoccipital, then slightly convex from supraoccipital to dorsal origin and from last dorsal-fin ray to caudal peduncle, then straight to base of caudal fin.Ventral profile of body convex from snout to base of pelvic fin, oblique along anal-fin base, then straight to base of caudal fin.Head and snout large, mandibles equal; mouth terminal, lips soft and flexible, not covering outer row of premaxillary teeth; ventral border of upper mandible oblique; posterior edge of maxilla reaching anterior edge of orbit; opening of posterior nostrils vertically ovoid.
Premaxilla with two rows of teeth, outer row with four to five tricuspid teeth; internal row with four, the first three pentacuspid and the last tricuspid, diminishing gradually in size laterally.Maxilla extends beyond posteroventral edge of the second infraorbital, and has 6-8 tricuspid teeth in a series not reaching anteroventral margin of that bone.Four anterior most dentary teeth larger, with five cusps, followed by six medium-sized tricuspid teeth (Fig. 2).
Color in alcohol.Body dark brownish-yellow, chromatophores more densely concentrated on dorsum, most intense on head and extending to anterior part of dentary.Midlateral body with dark stripe from posterior margin of eye, interrupted at humeral spot and then continuing posteriorly onto middle caudal-fin rays.Humeral spot vertically elongate, located near posterior margin of opercle, extending from second to fifth scale of lateral line series and extending three to five scale rows below the lateral line series.Ventral part of body light yellow.Posterior margin of scales on dorsal region of body dark.Dorsal and anal fin with strong concentration of chromatophores along distal margin.Adipose dark brown.Caudal-fin with dark chromatophores on middle rays.Pectoral and pelvic fins as well as caudal-fin lobes hyaline.Dorsal fin with chromatophores concentrated mostly on interradial membranes and distal margins of anterior rays.

Color in life.
Counter-shaded and with silvery lateral stripe highlighted in iridescent yellowish-green, more conspicuous along dorsal margin of stripe.Dorsal margin of opercle anterior to lateral stripe intense violet.Dorsal margin of eye yellow.Infraorbital along posterior margin of orbit violet, this color extending along dorsal half of opercle.Head beneath orbit intense blue.Scales on sides of body without melanophores, giving it a whitish or silvery appearance.Dorsal region dark violet.Wide dark humeral spot, conspicuous beneath silvery lateral stripe, extending through it but with less intensity.Posterior part of caudal peduncle with dark midlateral stripe that extends on to middle caudal-fin rays; ventral margin of lateral stripe reddish on caudal peduncle.Ventral posterior portion of caudal peduncle red.Pectoral and pelvic fins hyaline, anal and dorsal fins with reddish bar crossing middle sections of rays, more notable in males, distal tips of dorsal and caudal fins dark.Adipose fin iridescent red.
Sexual dimorphism.Males have hooks on anal, pelvic and pectoral-fin rays.There are five to nine pairs of hooks located on the middle and distal portions of last unbranched and first to seventh branched anal-fin rays.All branched pelvic-fin rays have ten to 20 small hooks all along most of ray's length, no hooks on unbranched rays.There are small, poorly developed hooks on the extreme distal portions of the pectoral-fin rays.
Etymology.Named for the collection locality, in the Sierra Nevada of Santa Marta drainage, north from Colombia.

Distribution and ecological notes:
This species is so far known from the upper Gaira and Río Frío drainages, in the Sierra Nevada of Santa Marta, Caribbean coastal drainages of northern Colombia (Fig. 3).Hemibrycon sierraensis was captured in streams characterized by relatively rapid water current, running over rocky and sandy bottoms with high transparency (Fig. 4).The pH was near neutral, dissolved oxygen and percent saturation of oxygen values were high (Table 2) typical of oligotrophic environments.The new taxon is allopatric with Hemibrycon santamartae, a species found in the more eutrophic waters of the Ranchería River and its tributaries.Analysis of stomach contents of four specimens revealed presence of filamentous algae, fragments of vascular plants, adults and larvae of two different species of Trichoptera (Hydropsychidae), adult Formicidae and fragments of unidentified arthropods.The presence of allochthonous and autochthonous items suggests that this species is omnivorous.
Comments: A discriminant analysis that included species from adjacent watersheds did not distinguish among most species based on morphology, but did separate Hemibrycon sierraensis.H. sierraensis is distinguished from H. boquiae, H. colombianus, H. santamartae, H. dariensis, H. cardalensis, H. metae, H. palomae, H. polyodon, and H. jabonero    length and caudal peduncle depth (Fig. 5).The first canonical axis explained 46,8% of the total variability and the second 19,8%, between the first and third canonical axis explained the 81% of the variation (Fig. 6).

DISCUSSION
Hemibrycon sierraensis has all of the synapomorphies observed in other Hemibrycon (Mirande, 2010;Arcila-M. 2008).Although most species of Hemibrycon are similar in color pattern throughout their geographic distribution, subtle differences in the concentration and distribution of black pigment in the humeral and caudal regions, have been used to identify new diversity (Bertaco & Malabarba, 2010;Román-Valencia, Vanegas-Ríos & García, 2009a;Román-Valencia et al., 2009b;Román-Valencia & Arcila-Mesa, 2010).In addition to a red adipose fin, Hemibrycon sierraensis has a red spot on the ventral portion of the caudal peduncle, a character that also been  observed in several other species of Hemibrycon (Bertaco et al., 2007;Román-Valencia et al., 2010), leading us to infer that it represents a synapomorphy for the genus as suggested by Arcila-M (2008).The bright red adipose fin is a possible autapomorphy for this new species and has not been observed in other species of the genus.
The character traditionally used to define Hemibrycon is having the toothed portion of anterior margin of the maxilla longer than the untoothed portion (Eigenmann, 1927).However, this character is probably homoplastic and is present in other genera of Characidae such as Brycon, Roeboides and Pseudochalceus.
appreciate the help of the students of Biology, 2012-2, of the University of Atlántico, who helped collect the type material.Two reviewers evaluated the manuscript and gave many valuable suggestions.
iii, 26*(28) or 27(58).Anal-fin origin posterior to vertical through base of first dorsal-fin ray.Pectoral-fin rays i,10*,i (46) or 11(40).Dorsal-fin rays ii,7,i*; Pelvic-fin rays i,6,i*; in both fins the last ray is simple; first unbranched ray approximately one-half length of second ray, its tip reaching first bifurcation of first branched ray.Pelvic-fin insertion anterior to vertical through dorsal-fin origin.Caudal fin forked with short pointed lobes not covered with scales.Total number of vertebra 40-41 (n=4).
along canonical axis one by differences in interorbital distance, postorbital distance, head

TABLE 1
Morphometric data of Hemibrycon sierraensis n. sp (n=86) Standard and total lengths in mm.Mean values in parenthesis.SD = Standard deviation.