Cyphocharax boiadeiro, Melo, Bruno F., 2017

Melo, Bruno F., 2017, Cyphocharax boiadeiro, a new species from the upper rio Araguaia, Amazon basin, Brazil (Characiformes: Curimatidae), Zootaxa 4247 (2), pp. 114-120 : 115-119

Cyphocharax boiadeiro , new species

( Figs. 1–2 )

Holotype. LIRP 14133, 42.9 mm SL, Brazil, Mato Grosso, Alto Araguaia, córrego do Sapo, upriver Couto Magalhães falls , rio Araguaia , 17°31’10.6”S 53°15’33.0”W, 7–8 Aug 2002, A.L.A. Melo & L.S.F. Martins.

Paratypes. All from Brazil: LBP 1446, 3, 46.5–60.7 mm SL (tissues 12595 and 12596), Mato Grosso, Alto Araguaia, rio Boiadeiro , rio Araguaia basin, 17°19’19.4”S 53°14’25”W, 6 May 2003, C. Oliveira et al. LBP 22741, 3, 34.1–41.4 mm SL, same data as holotype . LIRP 4424, 13 , 17.0– 47.9 mm SL, same data as holotype . LIRP 4499, 6 , 18.1–45.7 mm SL, same data as holotype . MZUSP 41841, 1 , 49.2 mm SL, Mato Grosso, Alto Araguaia, swamp at córrego do Rancho, rio Araguaia basin, 17°15’00”S 53°23’00”W, 24 Sep 1988, L.P.S. Portugal & M.M.A. Oliveira . MZUSP 73319, 5 , 24.0– 53.4 mm SL, Mato Grosso, Alto Araguaia, córrego Sapinho, km 747.64 of the Ferronorte railroad, rio Araguaia basin, 17°25’55”S 53°14’34”W, 19 May 2001, C.R. Moreira & F.C. T . Lima.

Diagnosis. Cyphocharax boiadeiro differs from all congeners, except C. saladensis , C. signatus and C. spilotus , by having a distinct longitudinal dark stripe running from supracleithrum to the caudal peduncle, stripe interrupted in some specimens, and with a gradual fading of that pigmentation at the vertical line through adiposefin insertion to anterior margin of the dark mark on the caudal peduncle ( Figs. 1–2 ) (vs. absence of such pigmentation pattern). Cyphocharax boiadeiro can be distinguished from C. saladensis by having the dark patch of pigmentation restricted to the midlateral surface of the caudal peduncle in specimens longer than 40 mm SL (vs. dark patch of pigmentation on caudal peduncle more elongate and rounded, extending anteriorly to vertical line through or anterior to adipose fin in specimens longer than 40 mm SL). Cyphocharax boiadeiro differs from C. signatus by having 13–16 pectoral-fin rays (vs. 10–12), the non-prolongation of the anal-fin rays (vs. relatively elongate anal-fin rays) and the caudal peduncle not shortened (vs. caudal peduncle relatively short). It differs from C. spilotus by having nine branched dorsal-fin rays (vs. 10–12 branched dorsal-fin rays). Cyphocharax boiadeiro differs from all congeners, except C. aninha , C. gangamon , C. punctatus , C. saladensis , C. signatus and C. vexillapinnus by the presence of a truncate laterosensory system that results in specimens with incomplete pored scales that increase in larger specimens (vs. laterosensory system developed with complete lateral line). Cyphocharax boiadeiro further differs from C. laticlavius , C. modestus and C. naegelii by the presence of a rounded to horizontally elongated patch of dark pigmentation restricted to the midlateral surface of the caudal peduncle (vs. prolongation of the dark stripe of the midlateral surface of body into the caudal peduncle). Cyphocharax boiadeiro further differs from C. helleri , C. multilineatus and C. pantostictus by the presence of a single dark stripe along the midlateral surface of the body (vs. multiple series of longitudinal dark stripes or spot rows running between scale rows in the midlateral surface of the body). It can be also distinguished from C. biocellatus , C. jagunco , C. lundi , C. punctatus , C. vanderi and C. voga by the well-defined dark stripe (vs. presence of two or more dark spots along the lateral surface of body).

Description. Morphometric data is presented in Table 1. Body moderately elongate. Dorsal profile of head moderately convex from tip of snout to dorsal-fin origin; slightly convex along dorsal-fin base; straight from base of last dorsal-fin ray to adipose-fin origin and then slightly concave to origin of anteriormost dorsal caudal-fin procurrent ray. Ventral profile of head convex from anterior margin of lower lip to isthmus. Ventral profile of body smoothly convex from isthmus to pelvic-fin origin, convex from that point to terminus of anal-fin base and then slightly concave to origin of anteriormost ventral caudal-fin procurrent ray. Prepelvic region somewhat flattened transversely. Postpelvic region of body transversely rounded.

TABLE 1. Morphometric data for holotype and 25 paratypes of Cyphocharax boiadeiro . Range includes holotype and all paratypes. SD = standard deviation. Head profile rounded anteriorly, overall profile of head pointed. Upper jaw longer than lower jaw. Mouth subterminal, horizontally aligned with ventral margin of orbits. Nostrils very close; anterior nostrils circular to ovoid, posterior nostrils crescent-shaped with aperture not closed by thin flap of skin separating nares. Adipose eyelid slightly developed anterior to orbit.

Dorsal fin pointed, with distal margin straight and first and second branched rays longest. Distal margin of pectoral fin slightly rounded. Tip of adpressed pectoral fin reaches three or four scales short of vertical through pelvic-fin origin. Pelvic fin profile pointed. Tip of adpressed pelvic fin reaches three or four scales short of analfin origin. Caudal fin forked. Adipose fin present. Anal fin emarginate, anteriormost branched rays twice length of ultimate ray. Tip of adpressed anal fin reaches one scale short of origin of ventralmost caudal-fin ray.

Lateral line longitudinal scales from supracleithrum to hypural joint 27 (9), 28* (12) or 29 (3). Pored scales 6 (5), 7 (2), 8 (5), 9 (2), 11 (2), or 12 (1) in specimens smaller than 30 mm SL; pored scales 10 (2), 12* (1), 18 (1), 27 (2), or 28 (1) in specimens larger than 30 mm SL; number of pored scales increasing with standard length. Continuous series of scales posterior to hypural joint 2* (17) or 3 (7). Scales in transverse series from dorsal-fin origin to lateral line 4 (1) or 5* (23). Scales in transverse series from lateral line to anal-fin origin 4* (26). Scales between anus and anal-fin origin 1* (25). Middorsal series of scales from tip of supraoccipital to dorsal-fin origin 10 (17), 11* (5), or 12 (1). Circumpeduncular scales 14 (6), 15 (5), or 16* (12). Adherent scales present over basal portions of pelvic fin; scales primarily covering last unbranched fin-ray.

Dorsal-fin rays iii,9* (26), first unbranched ray very short. Anal-fin rays iii,7* (23) or iii,8 (3), first ray very short. Pelvic-fin rays i,7 (2), i,8* (21), ii,8 (2) or i,9 (1). Pectoral-fin rays i,12 (2), i,13 (4), i,14* (12) or i,15 (3). Total vertebrae 28 (4) or 29 (1).

Coloration in alcohol. Ground coloration of specimens fixed in alcohol brownish; those fixed in formalin yellowish. Overall coloration of larger specimens lacking guanine on scales. Upper lip, snout, and dorsal portion of head and opercle with small, dark chromatophores; lower jaw with field of dark chromatophores, more so along margin of lower lip. Margins of scales along lateral, dorsolateral, and dorsal surface of body outlined by series of small dark chromatophores, forming reticulate patern; more difuse pattern of small chromatophores imparting darker coloration on dorsal and dorsolateral regions of body. Dark pigmentation absent on scales on lateral surface of body ventral to horizontal through base of pectoral fin and on abdominal region. Deep-lying dusky stripe resulted from concentration of dark chromatophores under the midlateral scale series that run along midlateral surface of body from supracleithrum to anterior margin of the dark mark on the caudal peduncle. Stripe most evident in central region under dorsal fin. Stripe fainter from point under adipose-fin origin to anterior margin of the dark mark on the caudal peduncle. Stripe interrupted in some specimens; juveniles with low concentration of chromatophores in that region ( Fig. 2 ). Rays of dorsal, caudal, and anal fins distinctly outlined by small, dark chromatophores. Pectoral and pelvic fins scattered by small, dark chromatophores. Adipose fin dusky.

Distribution. Cyphocharax boiadeiro is only known from headwaters of the rio Araguaia, Amazon basin ( Fig. 3 ), at the municipality of Alto Araguaia, Goiás / Mato Grosso state boundary in central Brazil.

Etymology. The specific epithet boiadeiro is in reference to the rio Boiadeiro , one of the paratype localities near municipality of Alto Araguaia, state of Mato Grosso, Brazil. The name also honors the boiadeiros (cowboys in English and vaqueros in Spanish), cattle handlers mounted on horseback who perform multiple ranch-related tasks. Boiadeiros from central Brazil preserve their classic traditions and influenced regional lifestyles, food and music. A noun in apposition.

Remarks. No synapomorphies supporting the monophyly of Cyphocharax were identified in a broad intergeneric relationships study within the Curimatidae ( Vari, 1989) and the anatomical study associated to the taxonomic revision of genus ( Vari, 1992). In addition, these studies could not resolve interspecific phylogenetic relationships although morphological variations associated to body and fin pigmentation, laterosensory system, and modifications in the infraorbitals provided support to putative intrageneric subunits. One of them contains 26 species of Cyphocharax ( C. aninha , C. biocellatus , C. gangamon , C. gilbert , C. gillii , C. gouldingi , C. helleri , C. jagunco , C. laticlavius , C. lundi , C. meniscaprorus , C. mestomyllon , C. modestus , C. naegelii , C. oenas , C.

pantostictus , C. punctatus , C. saladensis , C. santacatarinae , C. sanctigabrielis , C. signatus , C. spilotus , C. spiluropsis , C. spilurus , C. vanderi , and C. voga ) that possess a patch of dark pigmentation on the midlateral surface of the caudal peduncle ( Vari, 1992, Vari et al., 2012; Wosiacki & Miranda, 2013; Melo & Vari, 2014; Dutra et al., 2016) despite in absence of a phylogenetic analysis. Cyphocharax boiadeiro also shares such putative synapomorphy.

Truncation of the laterosensory canal system resulting in incomplete series of pored scales is another putative synapormorphy proposed to include Cyphocharax punctatus , C. saladensis and C. vexillapinnus ( Vari, 1992) supplemented by C. signatus and C. aninha ( Wosiacki & Miranda, 2013) . Vari (1992) extensively discussed such feature as a derived condition and concluded that the incomplete poring but ontogenetically lengthened lateral line in C. punctatus (i.e. number of pored scales increases proportionally with the size of specimens) is not homologous with the constant truncated lateral line of C. saladensis , C. vexillapinnus ( Vari, 1992) , C. signatus and C. aninha ( Wosiacki & Miranda, 2013) . The pattern observed in C. boiadeiro follows the ontogenetic lengthening as that observed in C. punctatus , and in fact in C. gangamon as well, which points to a close relationship among these species. Cyphocharax gangamon possesses incomplete lateral line in specimens of about 25 mm SL, increasing to a complete series in specimens greater than 32 mm SL ( Vari, 1992), pattern comparable to C. punctatus and C. boiadeiro . Interestingly, members of this broader group ( C. aninha , C. boiadeiro , C. gangamon , C. punctatus , C. saladensis , C. signatus , C. vanderi and C. vexillapinnus ) contain fewer scales along the longitudinal series from supracleithrum to hypural joint (27–30, rarely 31 in C. vexillapinnus ), with sole exception of C. aninha (29–35). Thus, such morphological features shared among them might support a putative monophyletic lineage.

Figures

FIGURE 1. Cyphocharax boiadeiro, LIRP 14133, holotype, 42.9 mm SL, Brazil, Mato Grosso, Alto Araguaia, upper rio Araguaia basin.

FIGURE 2. Cyphocharax boiadeiro, LIRP 4424, paratypes, Brazil, Mato Grosso, Alto Araguaia, upper rio Araguaia basin. A) 47.9 mm SL. B) 37.9 mm SL. C) 35.5 mm SL. D) 31.3 mm SL. E) 21.8 mm SL.

FIGURE 3. Map of central Brazil basin showing the collection localities of Cyphocharax boiadeiro (black symbols) in the upper rio Araguaia, municipality of Alto Araguaia, Mato Grosso. Circle represents holotype locality; squares represent paratype localities.