Cyphocharax sanctigabrielis, Melo & Vari, 2014

Melo, Bruno F. & Vari, Richard P., 2014, New species of Cyphocharax (Characiformes: Curimatidae) from the upper rio Negro, Amazon basin, Neotropical Ichthyology 12 (2), pp. 327-332 : 328-331

Cyphocharax sanctigabrielis , new species Fig. 1

Holotype. MZUSP 115004 , 60.7 mm SL, Brazil, Amazonas , São Gabriel da Cachoeira , Igarapé Nouba Uba , near BR-307 road, upper rio Negro, Amazon basin, 00°00.321’N 66°55.357’W, 9 Aug 2008, C. Oliveira, M. I. Taylor, M. A. Alexandrou & J. I. R. Porto.

Paratypes. LBP 6963, 6, 44.3-67.0 mm SL (tissues 33399 and 33400); collected with holotype .

Diagnosis. Cyphocharax sanctigabrielis is distinguished from all other species of Cyphocharax by the presence on the lateral surface of the caudal peduncle of a distinct, longitudinally elongate, posteriorly often vertically expanded, darkly pigmented mark extending anteriorly from the base of the median caudal-fin rays to the vertical through the posterior limit of the base of the adipose fin. Dark pigmentation on the caudal peduncle is absent in C. abramoides , C. aspilos , C. derhami , C. festivus , C. leucostictus , C. magdalenae , C. microcephalus , C. multilineatus , C. nigripinnis , C. notatus , C. pinnilepis , C. plumbeus , C. stilbolepis , and C. vexillapinnus . When present, the dark pigmentation in that region in other congeners can alternatively be rotund ( C. gangamon , C. gillii , C. gouldingi , C. helleri , C. mestomyllon , C. oenas , C. punctatus , C. spiluropsis , and C. vanderi ), somewhat triangular with its posterior border darker ( C. meniscaprorus ), a vertically oriented ellipsoid ( C. aninha ), in the form of an elongate stripe ( C. laticlavius , C. modestus , C. nagelii , and C. pantostictus ) or longitudinally ovoid but terminating anteriorly distinctly posterior to the vertical through the posterior limit of the base of the adipose fin ( C. biocellatus , C. gilbert , C. saladensis , C. santacatarinae , C. signatus , C. spilotus , C. spilurus , and C. voga ). Cyphocharax sanctigabrielis can be further diagnosed from various congeners by the absence of a series of dark stripes or spots running between the scale rows (vs. the presence of such dark pigmentation in C. helleri , C. multilineatus , and C. pantostictus ), the absence of two to eight dark spots distributed along the midlateral surface of the body (vs. the presence of such pigmentation in C. biocellatus , C. punctatus , and C. vanderi ), the absence of a patch of dark pigmentation on the dorsal or adipose fins (vs. the presence of such pigmentation in C. nigripinnis , C. notatus and C. vexillapinnus ) and a non-fleshy upper lip (vs. lip very fleshy in C. mestomyllon ). Cyphocharax sanctigabrielis can be meristically further distinguished from various other congeners by the possession of 31 pored scales along the lateral line from the supracleithrum to the hypural joint (vs. four to nine pored scales in C. aninha , C. saladensis and C. signatus , 27 in C. vanderi , 27 or 28 in C. gangamon and in sum 32 to 97 in C. abramoides , C. aspilos , C. gilbert , C. leucostictus , C. magdalenae , C. nagelii , C. nigripinnis , C. pinnilepis , C. platanus , C. santacatarinae , C. stilbolepis , and C. voga ), the presence of 9 branched dorsal-fin rays (vs. 10 to 12 in C. spilotus ), and the possession of 30 or 31 vertebrae (vs. 28 or 29 in C. vanderi and 32 to 37 in C. abramoides , C. aspilos , C. gilbert , C. modestus , C. nagelii , C. notatus , C. platanus , C. santacatarinae , C. stilbolepis , and C. voga ). Morphometric ratios and counts serve to further discriminate C. sanctigabrielis from various congeners (for comparative data see Vari, 1992a; Vari & Blackledge, 1996; Vari & Chang, 2006; Vari et al., 2010, 2012).

Description. Morphometric data presented in Table 1 . Body moderately elongate; elongation more pronounced in larger specimens. Dorsal profile of head convex from margin of upper lip to vertical through anterior nares, nearly straight from that point to posterior terminus of head. Dorsal profile of body slightly convex from tip of supraoccipital spine to dorsal-fin origin; straight to slightly convex and posteroventrally-slanted from base of last dorsal-fin ray to adipose-fin origin and then slightly concave to origin of anteriormost dorsal procurrent ray. Dorsal surface of body with barely apparent median ridge anterior to dorsal-fin base and transversely rounded posterior to fin base. Ventral profile of head very slightly convex to nearly straight from margin of lower lip to isthmus. Ventral profile of body smoothly convex from isthmus to pelvic-fin origin, convex from that point to rear of anal-fin base and then slightly concave to origin of anteriormost ventral procurrent ray. Prepelvic region smoothly flattened transversely, with midventral series of scales comparable in size to those on adjoining portions of body. Postpelvic region of body transversely rounded.

Dorsal fin pointed, with distal margin straight and first and second branched rays longest. Pectoral-fin profile pointed. Tip of adpressed pectoral fin falls four or five scales short of vertical through pelvic-fin origin. Pelvic fin profile pointed. Tip of adpressed pelvic fin falls one or two scales short of anus. Caudal fin forked with tips of lobes somewhat pointed. Adipose fin well developed. Anal fin emarginate with first branched ray longest and about three times length of ultimate ray. Tip of adpressed anal fin falls five or six scales short of point of origin of ventral most caudal-fin ray.

Head profile anteriorly pointed overall from lateral view, but rounded in region of mouth and snout. Upper jaw very slightly longer than lower jaw with mouth slightly subterminal or jaws equal. Nostrils very close; anterior circular to ovoid, posterior crescent-shaped with aperture closed by thin flap of skin separating nostrils. Adipose eyelid well developed and extending posteriorly onto anterodorsal portion of opercle. Smaller specimens with central aperture in adipose eyelid round and approximately corresponding to limits of pupil. Opening in larger individuals vertically-ovoid with eyelid overlapping anterior and posterior portions of pupil.

All scales of lateral line pored with primary laterosensory canal straight. Pored lateral-line scales from supracleithrum to hypural joint 31* (7). Pored scales on basal portions of caudal fin posterior to hypural joint 2* (5) or 3 (2). Scales in transverse series from dorsal-fin origin to lateral line 5* (6) or 5½ (1). Scales in transverse series from anal-fin origin to lateral line 4*(3), 4½ (3) or 5 (1). Scales between anus and anal-fin origin 2* (6) or 3 (1). Middorsal series of scales from rear of supraoccipital spine to dorsal-fin origin 9* (6) or 10 (1). Smaller individuals lacking scales over caudal-fin lobes. Midsized and larger specimens with field of adherent scales continuing posteriorly onto basal portion of each caudal-fin lobe. Anterior scales similar in size to those on posterior portion of caudal peduncle. Adherent scales present over basal portions of pelvic fin; scales primarily covering last unbranched fin-ray.

Dorsal-fin rays iii,9* (7), with first unbranched ray very short. Anal-fin rays ii,7* (3) or iii,7 (4), with first ray very short when three unbranched rays present. Pelvic-fin rays ii, 9* (7). Pectoral-fin rays 14 (1) or 15* (6). Total vertebrae 30 (1) or 31* (6).

Coloration in alcohol. Ground coloration of specimens fixed in alcohol brownish; those fixed in formalin yellowish. Overall coloration of larger specimens retaining guanine on scales silvery or silvery golden. Dusky surface coloration darker on dorsal portion of head; head dusky dorsolaterally and light colored ventrally. Chromatophores on postorbital region of head slightly larger than those on snout other than in area posterior of orbit overlapped by adipose eyelid. Overall pigmentation of that portion of postorbital region consequently somewhat lighter than that of adjoining areas.

Dusky surface coloration darker on dorsal and dorsolateral regions of body. Ground coloration of body more yellowish ventrally. Dusky surface coloration darker on dorsal and dorsolateral regions of body. Ground coloration of body more yellowish ventrally. Deep-lying, dark chromatophores forming faint, dusky midlateral stripe on body. Stripe most evident posterior of vertical through base of ultimate dorsal-fin ray and with posterior section of stripe slightly expanded vertically. Stripe continues to anterior margin of patch of dark pigmentation on midlateral surface of caudal peduncle. Middorsal region of body with series of small dark chromatophores running from tip of supraoccipital spine to anterior border of adipose fin, darker than adjoining areas. Scales on dorsal and dorsolateral regions of body with dark central regions. Light versus dark regions cumulatively forming overall reticulate pattern on those portions of body. Dark chromatophores sparsely distributed over central portion of exposed region of scales but more concentrated anteriorly. Dark pigmentation absent on scales on lateral surface of body ventral to horizontal through base of pectoral fin and also on abdomen.

Dorsal, anal, and caudal fins somewhat dusky, with ray margins outlined by small, dark chromatophores. Dark pigmentation most developed distally on caudal-fin lobes, dorsal fin, and anterior rays of anal fin. Pectoral and pelvic fins hyaline overall, but with rays outlined by small, dark chromatophores. Adipose fin speckled with small dark chromatophores.

Distribution. Cyphocharax sanctigabrielis is presently known from the upper rio Negro, Amazon basin ( Fig. 2 ). The type locality, Igarapé Nouba Uba ( Fig. 3 ) empties into the rio Negro upriver of the city of São Gabriel da Cachoeira.

Habitat notes. The Igarapé Nouba Uba ( Fig. 3 ) is a shallow (30-50 cm), slow-flowing stream over fine and sand substrate within a well-preserved forested setting with the stream borders lined with grasses and rushes.

Etymology. The species name, sanctigabrielis , is in reference to the município de São Gabriel da Cachoeira, Amazonas State, within which the new species was discovered.

Generic placement. As presently defined, Cyphocharax is delimited by the combination of the possession of the synapomorphies for a quadritomy formed by that genus, Curimatella , Pseudocurimata and Steindachnerina in conjunction with the absence of the synapomorphies diagnostic for each of those three other genera ( Vari, 1989a, 1989c, 1991, 1992a, 1992b). The absence of identified derived features common to the species of Cyphocharax leaves open the possibility that the closest relatives of Cyphocharax sanctigabrielis (and likely some other species in Cyphocharax ) lie with one of Curimatella , Pseudocurimata , and Steindachnerina rather than with their nominal congeners. That possibility notwithstanding, Cyphocharax sanctigabrielis lacks the externally obvious synapomorphies present in Curimatella ( Vari, 1989a: 58, 1992b: 4), Pseudocurimata (Vari, 1989c: 3) and Steindachnerina ( Vari, 1989: 58; 1991: 23). In the absence of such derived features, the new species is assigned to Cyphocharax under the present definition of that genus.

Figures

Fig. 1. Cyphocharax sanctigabrielis, holotype, MZUSP 115004, 60.7 mm SL, Igarapé Nouba Uba, rio Negro, Amazon basin, São Gabriel da Cachoeira, Amazonas State, Brazil. Views of preserved specimen (a) and radiograph (b).

Fig. 2. Map of Western Amazon basin showing the collection locality of Cyphocharax sanctigabrielis (yellow dot) in the upper rio Negro near São Gabriel da Cachoeira, Amazonas, Brazil.

Fig. 3. Igarapé Nouba Uba, type locality of Cyphocharax sanctigabrielis, upper rio Negro, near São Gabriel da Cachoeira, Amazon basin, northern Brazil.