Hemibrycon rafaelense n . sp . ( Characiformes , Characidae ) , a new species from the upper Cauca River , with keys to Colombian species C . Román – Valencia

Hemibrycon rafaelense n. sp. (Characiformes, Characidae), a new species from the upper Cauca River, with keys to Colombian species.— A new fish species of Hemibrycon is described from the San Rafael River, upper Cauca River, Colombia. H. rafaelense can be distinguished from other species of the genus by the number of cusps on the teeth in the internal premaxilla row (3–5 vs. 5–7 except H. surinamensis), by the number of predorsal scales (10–12 vs. 12–17, except H. jelskii and H. orcesi), and by poscleithrum 1 (much closer to postcleithrum 2 vs. postcleithrum 1 and 2 clearly separated). Ecological data of the aquatic habitat of the new taxon are presented and keys to help identify known Colombian species are included.


Introduction
Previous studies of Hemibrycon Günther in Colombia and adjacent localities focused on the taxonomy and description of new species (Eigenmann, 1913;Eigenmann et al., 1914;Eigenmann, 1922Eigenmann, , 1927;;Géry, 1977;Meek & Hildebrand, 1916;Schultz, 1944;Dahl, 1960Dahl, , 1971;;Dahl & Medem, 1964;Miles, 1971;Taphorn, 1992;Román-Valencia, 2001, 2004;Román-Valencia et al., 2006;Román-Valencia & Ruiz-C., 2007;Román-Valencia et al., 2007;Bertaco et al., 2007).Román-Valencia (2004) considered Hemibrycon tolimae a synonym of Bryconamericus tolimae, while Román-Valencia (2001) distinguished Hemibrycon boquiae from Bryconamericus caucanus and discussed the validity of traditional diagnostic characters for Hemibrycon.There is no modern phylogenetic hypothesis of relationships for this genus, and the characters used to define it have not proven significant in determining its monophyly.Most of these characters are little or non-informative and some coincide with those for other Characidae genera.When no hypothesis is available, it is not possible to reconstruct a spatial model to explain the current geographic distribution (Román-Valencia et al., 2007).The genus lives in secondary creeks between 41 to 1,910 m a.s.l., with crystalline waters flowing over substrates of stones, rocks, sand, or leaf litter in decomposition, with high dissolved oxygen (mean 8 ppm).Their diet is mainly aquatic and terrestrial insects of autochthonous and allochthonous origin (Román-Valencia & Botero, 2006).The purpose of this paper is to describe a new species of Hemibrycon from Colombia, as a further contribution to the ongoing revision of the genus.

Material and methods
Fishes were captured using a seine, preserved with 10% formalin and later stored in 70% ethanol.Measurements were made with digital calipers to 0.01-mm precision, and expressed as percentages of standard (SL) and head lengths (HL) (table 1).Measurements and counts were taken on the left side, except if this was damaged.Counts and measurements were recorded following the methodology described in Vari & Siebert (1990).We performed principal component analysis (PCA) on the correlation matrix of morphometric and meristic characters; for meristic characters we used the Mann-Whitney non-parametric rank-sum test for species in biogeographically proximity; bar graphs of 99% confidence were used to provide more information in the differentiation of species.
Observations of cartilage and bone were made on two cleared and stained specimens (C. and S.) following the modifications by Song & Parenti (1995) of the method outlined in Taylor & Van Dyke (1985).Bone nomenclature follows Weitzman (1962), Vari (1995) and Ruiz-C. & Román-Valencia (2006).Scale rows between dorsal-fin origin and lateral line 5-8 6

Description
Morphometric in table 1. Body elongate, anteriorly robust, dorsal profile of head convex; area above orbits convex.Dorsal profile of body curved from supraoccipital to dorsal-fin origin, oblique from last dorsal-fin ray to caudal-fin base.Ventral profile of body convex from snout to anal-fin base, convexity more pronounced beyond posterior portion of pectoral fins.Caudal peduncle laterally compressed in all specimens.Head and snout short; jaws equal, mouth terminal; lips soft and flexible, not covering external tooth row of premaxilla; ventral border of upper jaw slightly concave; opening of posterior nostrils vertically ovoid; opening of anterior nostrils with posterior membranous flap.
Six infraorbitals present, all with laterosensory canal; third infraorbital long, wide, with ventral and posterior borders in contact with preopercle.Supraorbital absent.Premaxilla with short lateral process, and two rows of teeth; outer row with 3-5 tricuspid teeth arranged in straight line.Inner row with 3-5 teeth, with central cusp larger.Maxilla short with posterior tip not reaching anterior border of third infraorbital.Maxilla with 8 to 12 teeth, with 1 to 3 cusps, along anterior and ventral border in some specimens (< 40 mm SL).Dentary with 2 to 3 large pentacuspid teeth followed by 8 small teeth with one to three cusps.
Rhinosphenoid cartilaginous and ossified, separated posteriorly from orbitosphenoid by mesethmoid cartilage.Orbitosphenoid with short, narrow apophysis present.Parasphenoid elongate and undivided posteriorly.Mesethmoid cartilage contacting dorsal and lateral margins of rhinosphenoid and extending to anterior extreme of parasphenoid.Anterior portion of parasphenoid covering posterodorsal surface of vomer cartilaginous; posterior portion of parasphenoid in contact with prootic and basioccipital.Nasal bones elongate, the anterior end of the nasal bone lies lateral and dorsal to the external surface of the premaxilar.Seven supraneurals between head and anterior dorsal fin.Four branchiosegal rays.One to two epurals.32-34 epineural, 23-24 epipleural, 11-13/12-13 procurrent rays.Dorsal-fin margin oblique, second ray unbranched and first two branched rays longest.
Pectoral girdle with sharp dorsal process on cleithrum reaching one-third length of supracleithrum.Cleithrum short.Pelvic-fin short, with tip of fin falling short of anal-fin origin.Pelvic bone elongate, short, straight and pointed; ischiatic process short, curved, with foramen in part upper and without apophysis.75° 56' 36'' W).
Key to the species of Hemibrycon from the Magdalena River Basin.Clave para las especies de Hemibrycon de la cuenca del río Magdalena. 1 19-25 branched anal-fin rays; males with hooks only on anal and pelvic fins H. colombianus 24-28 branched anal-fin rays; males with a few hooks on all fins except caudal 2 2 13-14 predorsal scales; 42-44 line lateral scales; three unbranched anal-fin rays; scales from lateral line to dorsal fin base 5-6 H. boquiae 10-12 predorsal scales; 40-42 line lateral scales; four unbranched anal-fin rays; scales from lateral line to dorsal fin base 6-8 H. rafaelense n. sp.Comments The morphometric characters provided little information to differentiate H. rafaelense from other Rio Magdalena Basin species and populations.Morphological differences between these similar forms are subtle.The first component of the PCA accounted for 40.24% (eigenvalue 2.81) of variability and the second 16.79% (1.17).Only a few specimens of H. rafaelense n. sp.overlapped with individuals of H. boquiae (fig.5 ).Meristic characters such as predorsal scales number (P [ 0001) (fig.6) and the number of pored lateral line scales (P [ 0001) (fig.7) allow the differentiation of H. rafaelense from H. boquiae.Males of both H. rafaelense and H. boquiae have very small hooks on all fins, except the caudal fin.This sexually dimorphic character was also reported in H. divisorensis (Bertaco et al., 2007).