A new endemic species of Bryconamericus (Characiformes, Characidae) from the Middle Cauca River Basin, Colombia

A new endemic species of Bryconamericus (Characiformes, Characidae) from the Middle Cauca River Basin, Colombia.— Bryconamericus caldasi, a new species, is described from the Middle Cauca River drainage, Andean versant of Colombia. The new species is distinguished from all congeners by: the number of predorsal scales (15–17 vs. 9–14); a wide anterior maxilla tooth, at least twice as wide as the posterior tooth, both of which are pentacuspid (vs. maxilla teeth of same size); a dark lateral stripe overlaid by a peduncular spot; and a reticulated pattern on the sides of body (vs. peduncular spot and other body pigments not superimposed over a dark lateral stripe). We found several differences that distinguish the new species from B. caucanus, the only sympatric congener: number of predorsal median scales (15–17 vs. 12–13); convex predorsal profile (vs. oblique); scale size and number of scale rows at caudal–fin base (small scales arranged in two or more rows vs. large scales in just one row); pectoral fins not or just reaching pelvic fin insertions (vs. pectoral fins reaching posterior to pelvic–fin insertions); and dorsal–fin origin position (at vertical through posterior tip of pelvic–fin vs. at a vertical anterior to pelvic–fin tip).


Introduction
Currently, 79 species are assigned to the genus Bryconamericus (Román-Valencia et al., 2008;Eschmeyer & Fricke, 2013). Of these, 22 valid species occur in Colombian watersheds (Román-Valencia et al., 2008, 2009a, 2009b, 2010, 2011, 2013, but only one species, B. caucanus, has been reported from the Río Cauca (Román-Valencia et al.,2009a), and it is known to have a wide geographic distribution in Colombia (Román-Valencia, 2003;Román-Valencia et al., 2009a). The known distribution of Bryconamericus in Colombia suggests that this genus is more diverse in Transandean than in Cisandean drainages, probably because of several geographic isolation events (Román-Valencia et al., 2009b).The description of this new species of Bryconamericus from the Middle Cauca River Basin is a result of our ongoing revision of the genus, and is further evidence of the undocumented biodiversity of Bryconamericus.

Material and methods
Measurements were taken with digital calipers, recorded to tenths of millimeters and usually expressed as percentages of standard (SL) or head length (HL) (table 1). Counts were made using a stereoscope with a dissection needle to extend the fins. In count ranges, values for the holotype are indicated with an asterisk (*). Counts and measurements were taken from the left side of specimens when possible and following the guidelines in Vari & Siebert (1990) and Armbruster (2012). The 21 morphometric characters analyzed in this study (table 1) were evaluated by Principal Component Analysis (PCA) using the Burnaby method to eliminate the influence of size with the PAST program, version 1.81 for Windows (Hammer et al., 2008).
Observations of bones and cartilage were made on cleared and stained specimens (C&S), prepared according to techniques outlined in Taylor & Van Dyke (1985) and Song & Parenti (1995). Bone nomenclature follows Weitzman (1962), Vari (1995), and Ruiz-C. & Román-Valencia (2006). In the lists of paratypes, the number of individuals is given immediately after the catalog number, which is followed by the range of standard length in mm (SL) for that lot; for example: IUQ 3223 (7) 51.1-66.9 mm SL, indicates seven individuals in lot IUQ 3223, with the smallest fish measuring 51.1 mm SL and the largest 66,9 mm SL. All collections were made in Colombia. Acronyms used follow Sabaj-Pérez (2010). Meters above sea level is abbreviated as m a.s.l., Municipio is translated as County.
Premaxilla with two rows of teeth and large rounded lateral process. Four to six teeth of outer row tricuspid. Inner row with four pentacuspid teeth of equal size. Maxilla long, exceeding two-quarter lengths of the second infraorbital, anterior margin with notches, with four tricuspid teeth, at least twice as wide as the posterior tooth. Dentary with four large pentacuspid teeth, gradually diminishing in size laterally. Supraoccipital spine short, covering anterior axis of neural complex.
Eight to nine supraneurals present between head and anterior part of dorsal-fin, located between sixth and thirteenth dorsal spine and the first dorsal pterygiophores. Proximal pterygiophores (26 to 28) of the anal fin completely ossified. Cleithrum with pointed dorsal process that does not surpass entire supracleithrum, which is joined to post temporal.
Secondary sexual dimorphism Sexually mature males have 15-22 hooks on anterior branched anal-fin rays, including first to ninth, and on one simple anal-fin ray with eight to ten hooks. They also have twelve to nineteen hooks along the ventral surface of branched pelvic-fin rays and one simple ray.  Color in alcohol Dorsum dark, greenish. Body with very dark lateral band from posterior edge of opercle to base of caudal fin. Humeral spot round with faint ventral and dorsal projections. Peduncular spot rounded, extending beyond caudal peduncle, continuing on to middle caudal-fin rays. Ventro-lateral region of body from snout tip to caudal peduncle light yellow. All fins gray, on the anal fin with dark bands on distal portions of rays.
Live colors Dorsum of body and head and postventral region dark greenish, with black pigment. Body silvery white with yellow lateral stripe. Middle caudal-fin rays covered by a narrow band of melanophores that forms a slender arc or half-moon shaped spot on caudal peduncle. There is a small purple spot between the fifth and sixth infraorbitals and the opercle. The opercle has melanophores concentrated on the posterior portion. Humeral spot dark and rounded with disperse pigments; dark caudal spot elongate and continued on to middle caudal-fin rays. Pectoral, and pelvic-fins hyaline, dorsal, anal and caudal-fins yellow, but distal tips of caudal-fin rays white, and anal-fin yellowish on anterior rays but with posterior rays and distal tips of anterior rays intense white; dispersed melanophores present on interradial membranes. Opercular area silvery blue covering posterior margin of eye, opercular bone series and extending on to ventral region of body. The analysis of stomach contents of three specimens revealed the presence of adults and larvae of different species of Diptera (12.5%, 4.0 mm 3 ), Diptera: Simulidae (12.5%, 3.0 mm 3 ), Diptera: Chironomidae (12.5%, 3.0 mm 3 ), Diptera: Dixidae (12.5%, 2.0 mm 3 ), Trichoptera: Leptoceridae (12.5%, 14.0 mm 3 ), Ephemeroptera: Baetidae (25%, 5.0 mm 3 ), Hymenoptera: Vespidae (12.5%, 2.0 mm 3 ). The presence of both autochthonous and some allochthonous items suggests that this species is insectivorous with a considerable plasticity in its diet.

Etymology
Bryconamericus caldasi named to honor the memory of the Colombian naturalist Francisco José de Caldas, who devoted his life to the study of Neotropical nature, and whose intellectual merit lies in having embraced the incipient patriotic fervor in the struggle for Colombian independence in the first half of the nineteenth century.

Comments
Principal component analyses performed on all species examined were not informative for most of them, but did distinguish Bryconamericus caldasi from the sympatric B. caucanus a by differences in pectoral-fin length, pelvic-fin length, caudal peduncle depth and dorsal-pectoral fin distance along the axis x, and snout length, postorbital distance and mandible superior distance along the axis y. The first component explained 87.5% of the total variability and the second 5.51%, for a total of 93.01% of the variation ( fig. 2).
Although we made several attempts to collect this new species in different tributaries of the middle Cauca and Risaralda rivers (see comparative examined material), it was only collected from La Libertad Creek. This is the first record of such a narrowly endemic species of Bryconamericus in South America.

Discussion
In most species of Bryconamericus, there are one or two large, rounded scales located at the base of the caudal lobes. Furthermore, squamation does not extend beyond one-third of the length of the caudal-fin rays, and when well preserved, scales do not cover the procurrent caudal-fin rays (Romàn-Valencia et al., 2013). In B. caldasi n. sp., these scales are smaller than in most species of Bryconamericus and arranged in two rows, showing an intermediate condition between other species of Bryconamericus and Knodus, in which there are more than two scale rows that cover more than the proximal third of the caudal-fin. Román-Valencia et al. (2009a) reported that the populations of B. caucanus from the middle Cauca River Basin were fairly uniform morphologically as analyzed using Principal Component Analysis, and in their osteology and meristic characters. However, in this study of the new species, we found that it differs from B. caucanus by the number of predorsal median scales, the length and position of the pectoral-fins, shape of the predorsal profile, number of scale rows at the base of the caudal-fin and position of the dorsal-fin.